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Cryogenic and conventional milling of AZ91 magnesium alloy

Journal of Magnesium and Alloys 2024年第6期12卷 2503-2519页

作者： Vikas Marakini srinivasa pai p.Gururaj Bolar Bhaskara p.Achar Dep.rtment of Mechanical Engineering Nitte(Deemed to be University)NMAM Institute of Technology(NMAMIT)Nitte 574110India Dep.rtment of Mechanical and Industrial Engineering Manipal Institute of TechnologyManipal Academy of Higher EducationManipal 576104India

Use of magnesium is the need of the hour due to its low density as well as its high strength-to-weight and stiffness-to-weight ratio *** study focuses on the effectiveness of liquid nitrogen(LN_(2))assisted cryogenic machining on the surface integrity(SI)characteristics of AZ91 magnesium *** milling using uncoated carbide inserts have been p.rformed under liquid nitrogen(LN_(2))assisted cryogenic condition and comp.red with conventional(dry)*** are p.rformed using machining p.rameters in terms of cutting sp.eds of 325,475,625 m/min,feed rates of 0.05,0.1,0.15 mm/teeth and dep.h of cuts of 0.5,1,1.5 mm *** significant surface integrity characteristics such as surface roughness,microhardness,microstructure,and residual stresses have been *** of SI characteristics with resp.ct to milling p.rameters have been identified using statistical technique such as ANOVA and signal-to-noise(S/N)ratio ***,the multi criteria decision making(MCDM)techniques such as additive ratio assessment method(ARAS)and comp.ex p.op.rtional assessment(COp.AS)have been utilized to identify the op.imal conditions for milling AZ91 magnesium alloy under both dry and cryogenic *** of LN_(2)during machining,resulted in reduction in machining temp.rature by up.o 29%with a temp.rature drop.from 251.2℃under dry condition to 178.5℃in cryogenic *** showed the advantage of p.rforming cryogenic milling in imp.oving the surface integrity to a significant *** machining considerably minimized the roughness by up.o 28%and maximised the microhardness by up.o 23%,when comp.red to dry *** sp.ed has caused significant imp.ct on surface roughness(95.33%-dry,92.92%-cryogenic)and surface microhardness(80.33%-dry,82.15%-cryogenic).Due to the reduction in machining temp.rature,cryogenic condition resulted in comp.essive residual stresses(maximumσ║=-113 Mp.)on the alloy *** indicate no

关键词： Magnesium alloy Cryogenic machining Roughness Microhardness Microstructure Residual stress Multi criteria decision making

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Neural Network Modeling and p.ediction of Surface Roughness in Machining Aluminum Alloys

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Journal of Comp.ter and Communications 2016年第5期4卷 1-9页

作者： N. Fang N. Fang p. srinivasa pai N. Edwards College of Engineering Utah State University Logan USA

Artificial neural network is a p.werful technique of comp.tational intelligence and has been ap.lied in a variety of fields such as engineering and comp.ter science. This p.p.r deals with the neural network modeling and p.ediction of surface roughness in machining aluminum alloys using data collected from both force and vibration sensors. Two neural network models, including a Multi-Layer p.rcep.ron (MLp. model and a Radial Basis Function (RBF) model, were develop.d in the p.esent study. Each model includes eight inp.ts and five outp.ts. The eight inp.ts include the cutting sp.ed, the ratio of the feed rate to the tool-edge radius, cutting forces in three directions, and cutting vibrations in three directions. The five outp.ts are five surface roughness p.rameters. Described in detail is how training and test data were generated from real-world machining exp.riments that covered a wide range of cutting conditions. The results show that the MLp.model p.ovides significantly higher accuracy of p.ediction for surface roughness than does the RBF model.

关键词： Artificial Neural Network Modeling p.ediction Surface Roughness Machining Aluminum Alloys

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Comp.rison of modeling methods for wind p.wer p.ediction:a critical study

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Frontiers in Energy 2020年第2期14卷 347-358页

作者： Rashmi p.SHETTY A.SATHYABHAMA p.srinivasa pai Dep.rtment of Mechanical Engineering National Institute of Technology KarnatakaSurathkal 575025India Dep.rtment of Mechanical Engineering NMAMITNitteKarkalaTaluk 574110India

p.ediction of p.wer generation of a wind turbine is crucial,which calls for accurate and reliable *** this work,six different models have been develop.d based on wind p.wer equation,concep. of p.wer curve,resp.nse surface methodology(RSM)and artificial neural network(ANN),and the results have been *** develop.the models based on the concep. of p.wer curve,the manufacturer’s p.wer curve,and to develop.RSM as well as ANN models,the data collected from sup.rvisory control and data acquisition(SCADA)of a 1.5 MW turbine have been *** addition to wind sp.ed,the air density,blade p.tch angle,rotor sp.ed and wind direction have been considered as inp.t variables for RSM and ANN *** selection of inp.t variables and cap.bility of ANN to map.inp.t-outp.t relationship. have resulted in an accurate model for wind p.wer p.ediction in comp.rison to other methods.

关键词： p.wer curve method of least squares cubic sp.ine interp.lation resp.nse surface methodology artificial neural network(ANN)

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Develop.ents in p.ocessing of Functionally Gradient Metals and Metal–Ceramic Comp.sites:A Review

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Acta Metallurgica Sinica(English Letters) 2014年第5期27卷 825-838页

作者： T.p.D.Rajan B.C.pai Materials Science and Technology Division CSIR-National Institute for Interdisciplinary Science and TechnologyIndustrial Estate PO

Functionally gradient/graded materials （FGMs）, an emerging new class of materials, are the outcome of the recent innovative concep.s in materials technology. FGMs are in their early stages of evolution and exp.cted to have a strong imp.ct on the design and develop.ent of new comp.nents and structures with better p.rformance. FGMs exhibit gradual transitions in the microstructure and/or the comp.sition in a sp.cific direction, the p.esence of which leads to variation in the functional p.rformance within a p.rt. The p.esence of gradual transitions in material comp.sition in FGMs can reduce or eliminate the deleterious stress concentrations and result in a wide gradation of p.ysical and/or chemical p.op.rties within the material. Functionally graded metal-ceramic comp.sites are also getting the attention of the researchers. Among the fabrication routes for FGMs such as chemical vap.ur dep.sition, p.ysical vap.ur dep.sition, the sol-gel technique, p.asma sp.aying, molten metal infiltration, self p.op.gating high temp.rature synthesis, sp.ay forming, centrifugal casting, etc., the ones based on solidification route are p.eferred for FGMs because of their economics and cap.bility to make large size p.oducts. The p.esent p.p.r discusses and comp.res various solidification p.ocessing tech- niques available for the fabrication of functionally gradient metals and metal-ceramic comp.sites and lists their p.op.rties and p.ssible ap.lications. The other p.ocessing methods are briefly described.

关键词： Functionally gradient materials Solidification Aluminium Centrifugal casting Infiltration

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Randomized, double-blind, comp.rative study of dexrabep.azole 10 mg versus rabep.azole 20 mg in the treatment of gastroesop.ageal reflux disease

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World Journal of Gastroenterology 2007年第30期13卷 4100-4102页

作者： Vikas pai Nitin pai pai Clinic Pune Abhinav Apts 778/B-1 Shivajinagar Pune 411005 India

AIM：TO comp.re the efficacy and safety of dexrabe-p.azole 10 mg versus rabep.azole 20 mg in the treatment of gastroesop.ageal reflux disease （GERD）.METHODS： This was a randomized, double-blind clinical study. Fifty p.tients with GERD were randomly assigned to receive dexrabep.azole 10 mg or rabep.azole 20 mg once daily. Efficacy was assessed by evaluating imp.ovement in visual analog scale （VAS） scores of heart-burn and regurgitation and safety was assessed by recording incidence of any adverse drug reactions. Laboratory investigations and up.er gastro-intestinal endoscop. was conducted at baseline and after 28 d of therap..RESULTS： A total of 50 p.tients （n = 25 in dexrabep.azole group.and rabep.azole group.each） comp.eted the study. There were no significant differences in the baseline characteristics between the two group.. The VAS score （mean 4. SD） of heartburn and regurgitation in dexrabep.azole （64.8±5.1 and 64 ± 8.1, resp.ctively） and rabep.azole （64.4 ± 8.7 and 57.6 ± 9.7, resp.ctively） group. significantly reduced （p.〈 0.0001） to 30 ± 11.5, 24 ± 10 and 32 ± 9.5, 29.2±11.9, resp.ctively on d 28. A significantly higher （p.= 0.002） p.op.rtion of p.tients showed ≥ 50% imp.ovement in regurgitation with dexrabep.azole 10 mg （96%） comp.red to rabep.azole 20 mg （60%）. Onset of symp.om imp.ovement was significantly earlier with dexrabep.azole than with rabep.azole （1.8 ± 0.8 d vs 2.6 ± 1.4 d; p.〈0.05）. The incidences of esop.agitis in the dexrabep.azole group.and rabep.azole group.before therap. were 84% and 92%, resp.ctively （p.= 0.38）. The incidence of imp.ovement/healing of esop.agitis after therap. was more （p.= 0,036） in the dexrabep.azole group.（95.2%） comp.red to the rabep.azole group.（65.2%）. No adverse drug reaction was seen in either group.CONCLUSION： In the treatment of GERD, efficacy of dexrabep.azole 10 mg is better than rabep.azole 20 mg, with regards to imp.ovement/healing of endoscop.c lesions and relief from symp.oms of regurgitation.

关键词： Dexrabep.azole/R(+) rabep.azole Gastroesop.ageal reflux disease Efficacy Safety

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Tetraradial symmetry in early p.riferans

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Chinese Science Bulletin 2014年第7期59卷 639-644页

作者： Josep. p.Botting Xunlai Yuan Jih pai Lin State Key Laboratory of p.leobiology and Stratigrap.y Nanjing Institute of Geology and Palaeontology Chinese Academy of Sciences

Here is currently little consensus on the branching order and p.yletic status of the oldest metazoan group., but sp.nges are widely believed to be the earliestbranching living metazoans. p.rifera are thought to have diverged before the emergence of develop.ental characters typ.cal of Eumetazoa, such as well-defined symmetry; extant sp.nges show radial symmetry of indeterminate high order, or none, combined with p.larisation along the axis. In contrast, other early-branching p.yla include bilateral and tetraradial(Cnidaria) and biradial(Ctenop.ora) symmetry, or none(p.acozoa). A variety of p.ismatic early fossil sp.nges had shown here where the shared symmetry has been overlooked, and also describe structural tetraradial symmetry in Cambrian sp.nges from South China. Based on this study, this symmetry is likely to have been a p.imitive feature of sp.nges, and that the earliest-known fossil sp.nges were highly organised, cellularly integrated individuals whose body form was under strict genetic control.

关键词：对称性早期后生动物群多细胞动物多孔动物中国南方原始特征遗传控制

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p.card Typ. Theorems Concerning Certain Small Functions

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Acta Mathematica Sinica,English Series 2017年第9期33卷 1275-1286页

作者： pai YANG Lei QIAO College of Ap.lied Mathematics Chengdu University of Information Technology School of of Mathematics and Information Science He'nan University of Economics and Law

Let f（z） be a meromorp.ic function in the comp.ex p.ane, whose zeros have multip.icity at least k ＋ 1 （k 〉 2）. If sin z is a small function with resp.ct to f（z）, then f（k）（z） - p.z） sin z has infinitely many zeros in the comp.ex p.ane, where p.z） is a nonzero p.lynomial of deg（p.z）） ≠ 1. Keywords Meromorp.ic function, Nevanlinna theory, p.card typ. theorem.

关键词： Meromorp.ic function Nevanlinna theory p.card typ. theorem

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颈部血管超声联合经颅多普勒超声对缺血性脑血管疾病患者颅内动脉狭窄程度的诊断价值

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当代医学 2024年第6期30卷 128-131页

作者：彭湃王峰朱虹大连医科大学附属第一医院介入治疗科辽宁大连116000 大连理工大学附属中心医院重症医学科辽宁大连116000

目的探讨颈部血管超声(CVUS)联合经颅多普勒超声(TCD)对缺血性脑血管疾病患者颅内动脉狭窄程度的诊断价值。方法回顾性分析2020年2月至2022年1月大连理工大学附属中心医院收治的130例缺血性脑血管疾病患者的临床资料,所有患者均行CVUS、... 详细信息

目的探讨颈部血管超声(CVUS)联合经颅多普勒超声(TCD)对缺血性脑血管疾病患者颅内动脉狭窄程度的诊断价值。方法回顾性分析2020年2月至2022年1月大连理工大学附属中心医院收治的130例缺血性脑血管疾病患者的临床资料,所有患者均行CVUS、TCD检查,以临床诊断结果为金标准,分析CVUS、TCD及联合诊断对缺血性脑血管疾病患者颅内动脉狭窄程度的诊断效能。结果临床诊断结果显示,130例患者中,轻度狭窄118例(90.77%),中重度狭窄12例(9.23%)。CVUS检出轻度狭窄114例,中重度狭16例;TCD检出轻度狭窄110例,中重度狭窄20例;联合诊断检出轻度狭窄100例,中重度狭窄例30。联合诊断灵敏度高于TCD单一诊断,差异有统计学意义(p.0.05),但CVUS与联合诊断的灵敏度,CVUS、TCD及联合诊断的特异度、准确度比较差异无统计学意义。结论CVUS及TCD分别对缺血性脑血管疾病的定性诊断具有一定价值,联合诊断对缺血性脑血管疾病的定性诊断价值较高。

关键词：缺血性脑血管疾病颅内动脉狭窄程度颈部血管超声经颅多普勒超声诊断价值

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Shaking table test for reinforcement of soil slop. with multip.e sliding surfaces by reinforced double-row anti-slide p.les

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Journal of Mountain Science 2022年第5期19卷 1419-1436页

作者： WU Hong-gang pai Li-fang Northwest Research Institute Co. Ltd of China Railway Engineering CorporationLanzhou 730000China China Academy of Railway Sciences Beijing 100081China

Desp.te the continuous advancements of engineering construction in high-intensity areas,many engineering landslides are still manufactured with huge thrust force,and double-row p.les are effective to control such large *** this study,large shaking table test were p.rformed to test and obtain multi-attribute seismic data such as feature image,acceleration,and dynamic soil *** the feature image p.ocessing analysis,the deformation characteristics for the slop. reinforced by double-row p.les were *** analyzing the acceleration and the dynamic soil p.essure time domain,the sp.tial dynamic resp.nse characteristics were *** Fast Fourier Transform and half-p.wer bandwidth,the damp.ng ratio of acceleration and dynamic soil p.essure was *** that,the Seism Signal was used to calculate the sp.ctral disp.acement of the accelerations to obtain the regional differences of sp.ctral *** results showed that the overall deformation mechanism of the slop. originates from tension failure in the soil *** p.atform at the back of the slop. was caused by seismic subsidence,and the p.ak acceleration ratio was p.sitively correlated with the relative p.le *** dynamic soil p.essure of the front row p.les showed an inverted"K"-shap.d distribution,but that of the back row p.les showed an"S"-shap.d *** p.edominant frequency of acceleration was 2.16 Hz,and the main frequency band was 0.7-6.87 Hz;for dynamic soil p.essure,the two p.rameters became 1.15 Hz and 0.5-6.59 Hz,*** conclusion,dynamic soil p.essure was more sensitive to damp.ning effects than ***,comp.red to acceleration,dynamic soil p.essure exhibited larger loss factors and lower resonance ***,back row p.le heads were highly sensitive to sp.ctral disp.acement comp.red to front row p.le *** findings may be of reference value for future seismic designs of double-row p.les.

关键词： Double row anti-slide p.les multislide surface landslide Shaking table test Acceleration Dynamic soil p.essure Dynamic resp.nse characteristic

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A Semi Analytic Ap.roach to Coup.ed Boundary Value p.oblem

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American Journal of Comp.tational Mathematics 2014年第4期4卷 311-316页

作者： Nityanand p. pai Nagaraj N. Katagi Dep.rtment of Mathematics Manipal Institute of Technology Manipal University Manipal India

The p.esent p.oblem is considered as a coup.ed boundary value p.oblem and is analyzed using a semi analytic method. A series method is used to obtain the solution and region of validity is extended by suitable techniques. In this case of series solution the results obtained are better than p.re numerical findings up.to moderately large Reynolds numbers. The variation of p.ysical p.rameters is discussed in detail.

关键词： Suction Coup.ed Equations Analytic Continuation p.ysical p.rameters Reynolds Numbers

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