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Influence of laser peening on microstructure and fatigue lives of Ti-6Al-4V

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Transactions of Nonferrous Metals Society of China 2014年第10期24卷 3111-3117页

作者： S.ANAND KUMAr r.sundar S.GANESH sundarA rAMAN H.KUMAr r.KAUL K.rANGANATHAN S.M.OAK L.M.KUKrEJA K.S.BINDrA Department of Metallurgical and Materials Engineering IIT Madras Chennai-600036 India Solid State Laser Division RRCAT Indore 452013 India Laser Material Processing Division RRCAT Indore 452013 India

The influence of low energy laser peening on fatigue lives of Ti-6Al-4V was investigated. Laser peening was carried out on Ti-6Al-4V samples. Laser peened samples were characterized by residual stress analysis, surface roughness measurements, X-ray diffraction, optical microscopy, nanoindentation hardness tests, scanning and transmission electron microscopy and fatigue testing. Laser peening resulted in the formation of nanocrystallites on the surface and near surface regions with associated increase in hardness and introduction of compressive residual stress. Owing to positive influence of nanostructured surface and compressive residual stress, fatigue lives of the laser peened samples were significantly increased compared to the unpeened samples.

关键词： Ti-6Al-4V laser peening fatigue nanostructured surface

Is primary transcatheter aortic valve implantation the new normal?

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Journal of Geriatric Cardiology 2024年第4期21卷 458-461页

作者： r.Anantharaman C.sundar Kamal Kant Jena K.Arun Department of Cardiology Kauvery HospitalChennaiIndia

Degenerative calcific aortic valve stenosis(AS)is the most common valvular heart disease in elderly.^[1] It is well documented that symptomatic severe AS follows a malignant course leading to cardiogenic shock(CS).

关键词： aortic stenosis implantation

A Survey and Experimental review on Data Distribution Strategies for Parallel Spatial Clustering Algorithms

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Journal of Computer Science & Technology 2024年第3期39卷 610-636页

作者： Jagat Sesh Challa Navneet Goyal Amogh Sharma Nikhil Sreekumar.sundar Balasubramaniam Poonam Goyal Advanced Data Analytics and Parallel Technologies Laboratory Birla Institute of Technology and Science Pilani 333031India Uber New York 11101U.S.A. Computer Science and Engineering Department University of MinnesotaMinneapolis 55455U.S.A.

The advent of Big Data has led to the rapid growth in the usage of parallel clustering algorithms that work over distributed computing frameworks such as MPI,Mapreduce,and *** important step for any parallel clustering algorithm is the distribution of data amongst the cluster *** step governs the methodology and performance of the entire *** typically use random,or a spatial/geometric distribution strategy like kd-tree based partitioning and grid-based partitioning,as per the requirements of the ***,these strategies are generic and are not tailor-made for any specific parallel clustering *** this paper,we give a very comprehensive literature survey of MPI-based parallel clustering algorithms with special reference to the specific data distribution strategies they *** also propose three new data distribution strategies namely Parameterized Dimensional Split for parallel density-based clustering algorithms like DBSCAN and OPTICS,Cell-Based Dimensional Split for dGridSLINK,which is a grid-based hierarchical clustering algorithm that exhibits efficiency for disjoint spatial distribution,and Projection-Based Split,which is a generic distribution *** of these preserve spatial locality,achieve disjoint partitioning,and ensure good data load *** experimental analysis shows the benefits of using the proposed data distribution strategies for algorithms they are designed for,based on which we give appropriate recommendations for their usage.

关键词： parallel data mining data distribution parallel clustering spatial locality preservation

基于自适应双相场模型的纤维增强复合材料单层板断裂性能

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复合材料学报 2024年第3期41卷 1505-1515页

作者：郭雯马玉娥 sundar Natarajan 陈鹏程彭帆西北工业大学航空学院西安710072 Indian Institute of Technology Madras School of Mechanical EngineeringChennai 600036 长安大学理学院西安710064

相场法可以自动捕捉裂纹的萌生和演化,因此在模拟复合材料的复杂失效行为时具有明显优势。为区分纤维增强复合材料(Fiber-reinforced composites,FrC)中存在的不同断裂模式,采用双相场断裂模型来分别表征基体和纤维的损伤演化。同时采... 详细信息

相场法可以自动捕捉裂纹的萌生和演化,因此在模拟复合材料的复杂失效行为时具有明显优势。为区分纤维增强复合材料(Fiber-reinforced composites,FrC)中存在的不同断裂模式,采用双相场断裂模型来分别表征基体和纤维的损伤演化。同时采用相场变量作为误差指标,在各向异性的双相场模型中引入了基于四叉树分解的网格自适应细化策略。设计并开发了相应的Matlab程序,研究了单向及变刚度纤维增强复合材料单层板在拉伸位移载荷下的断裂行为。计算结果表明:采用基于自适应算法的各向异性双相场模型所得到的数值计算结果与试验结果吻合良好;自适应双相场模型能在保证较高计算精度的同时,配合序参量的演化准确地在裂纹路径上进行网格自动加密,简化网格前处理过程,减少网格数量,降低计算成本,提高计算效率。

关键词：纤维增强复合材料双相场各向异性自适应有限元

Integrated Analysis of Water Quality in Artificial Fishponds Using WQI and GIS in South-East Sierra Leone

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Journal of Geoscience and Environment Protection 2024年第1期12卷 145-163页

作者： Hadji D. S. Kallon Lamin r. Mansaray Misbah Fida Pratap sundar Shrestha Institute of Environmental Management and Quality Control Njala University Njala Sierra Leone School of Water and Environment Chang’an University Xi’an China Quality Control Laboratory of Njala University Njala Sierra Leone Department of Surveys and Geo-Informatics School of Environmental Sciences Njala University Njala Sierra Leone

Artificial fishponds play a pivotal role in global aquaculture, serving as a source of livelihood and nourishment for many communities. Ensuring the sustained health and productivity of Fishes in these environments relies heavily on water quality management. This assessment was done to determine the water quality of ten artificial fishponds in the south-eastern part of Sierra Leone using twelve physicochemical factors (pH, BOD, EC, TDS, turbidity, COD, Fe2+, Mg2+, Ca2+, NH3, , and alkalinity) to find out the Water Quality Index (WQI) and spatial distribution of respective parameters. The assessment of artificial fishponds using WQI and Inverse Distant Weighting (IDW) integration represents a relatively underexplored area within the domain of environmental water resources. The WQI was determined using the “Weighted Arithmetic Water Quality Index’’ method. The results of WQI in the study area range from 65.05 to 147.26. Several locations have water quality deemed unsuitable for consumption, while others range from good to very poor. It is essential to address and improve water quality in locations categorized as unsuitable for consumption and very poor to ensure safe and healthy water sources. It was also clear from the calculation that the smaller the mean concentration value of the pH as compared to the ideal value (7), the smaller the WQI value and the better the water quality. To keep the artificial fishpond water in good condition, mass domestic use should be controlled, and draining of surrounding organic matter should be stopped in ponds Bo_001, Kenema_001, and Kenema_002.

关键词： Physicochemical Parameters Water Quality Index WQI-“Weighted Arithmetic Index Method”

Analysis and Optimization of Operational and Pollutant Attributes of Diesel Engine with CNT-Infused Orange Peel Biodiesel-Diesel Blend Fuel

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Journal of Thermal Science 2024年第2期33卷 761-778页

作者： ranjeet rAI r.r.SAHOO Mechanical Engineering Department GLA UniversityMathura281406India Mechanical Engineering Department IIT(BHU)Varanasi221005India

The current study is performed to find sustainable solutions for the future of transportation and environmental *** conventional methods and experimental design table(L16 Orthogonal Array)techniques have been employed to examine and optimize a diesel-powered engine's operational and pollutant *** L16 Orthogonal Array is obtained through Taguchi's experimental design approach using Minitab 16 *** experimental design incorporated three control variables,namely engine speed,fuel type,and engine load,each with four *** operational parameters,namely brake thermal efficiency(BTE)and brake specific fuel consumption(BSFC),as well as the emission characteristics,including hydrocarbon(HC),carbon monoxide(CO),nitrogen oxide(NO),and smoke emissions,were acquired using the L16 orthogonal array(OA) and subsequently *** utilization of methodologies such as signal-to-noise(S/N) ratio and grey analysis was employed to determine the optimal operational state of the engine to achieve maximum performance while minimizing *** engine's ideal state of operation,in terms of BTE and BSFC,was determined to be at 75% engine load,1000 r/min engine speed,and using 10^(-4)(in vol) carbon nanotube incorporated 20% orange peel biodiesel(OPB20CNT100) blended fuel(A3-B1-C4).The study indicated that engine load significantly influenced BTE and BSFC,with 84.05% and 87.79% contribution factors,*** 25% engine load,1000 r/min,and OPB20CNT100 fuel(A1-B1-C4) CO,smoke,NO,and HC emissions were the *** load affects emissions the *** BSFC increased 3.10% and NO emissions 1.77%.BTE,CO,smoke,and HC emissions decreased by 1.9%,12.29%,47.05%,and 47.22%,respectively,at optimal operating conditions concerning diesel *** study shows that Taguchi-Grey's experimental design optimizes diesel engine operational and pollutant *** outcomes revealed that orange peel biodiesel infused with CNT can replace diesel fuel in a

关键词： Taguchi-Grey method OPB20CNT100 transesterification S/N ratio GrG HC CO and NO

Multidimensional images and aberrations in STEM

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Chinese Physics B 2024年第9期33卷 68-74页

作者： Eric r.Hoglund Andrew r.Lupini Center for Nanophase Materials Sciences Oak Ridge National LaboratoryOak RidgeTN 37831United States

recent advances in scanning transmission electron microscopy(STEM)have led to increased development of multidimensional STEM imaging modalities and novel image reconstruction *** interest arises because the main electron lens in a modern transmission electron microscope usually has a diffraction-space information limit that is significantly better than the real-space resolution of the same *** state-of-affairs is sometimes shared by other scattering methods in modern physics and contributes to a broader excitement surrounding multidimensional techniques that scan a probe while recording diffraction-space images,such as ptychography and scanning nano-beam ***,the contrasting resolution in the two spaces raises the question as to what is limiting their effective ***,we examine this paradox by considering the effects of aberrations in both image and diffraction planes,and likewise separate the contributions of pre-and post-sample *** consideration provides insight into aberration-measurement techniques and might also indicate improvements for super-resolution techniques.

关键词： scanning transmission electron microscopy (STEM) aberrations

Kinematic analysis of flexible bipedal robotic systems

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Applied Mathematics and Mechanics(English Edition) 2024年第5期45卷 795-818页

作者： r.FAZEL A.M.SHAFEI S.r.NEKOO Department of Mechanical Engineering Shahid Bahonar University of KermanKerman ***Iran Departamento de Ingenieria de Sistemas y Automatica Escuela Técnica Superior de IngenieriaUniversidad de SevillaSeville 41092Spain

In spite of its intrinsic complexities,the passive gait of bipedal robots on a sloping ramp is a subject of interest for numerous *** distinguishes the present research from similar works is the consideration of flexibility in the constituent links of this type of robotic *** is not a far-fetched assumption because in the transient(impact)phase,due to the impulsive forces which are applied to the system,the likelihood of exciting the vibration modes increases ***,the human leg bones that are involved in walking are supported by viscoelastic muscles and ***,for achieving more exact results,it is essential to model the robot links with viscoelastic *** this end,the Gibbs-Appell formulation and Newton's kinematic impact law are used to derive the most general form of the system's dynamic equations in the swing and transient phases of *** most important issue in the passive walking motion of bipedal robots is the determination of the initial robot configuration with which the system could accomplish a periodic and stable gait solely under the effect of gravitational *** extremely unstable nature of the system studied in this paper and the vibrations caused by the impulsive forces induced by the impact of robot feet with the inclined surface are some of the very serious challenges encountered for achieving the above-mentioned *** overcome such challenges,an innovative method that uses a combination of the linearized equations of motion in the swing phase and the algebraic motion equations in the transition phase is presented in this paper to obtain an eigenvalue *** solving this problem,the suitable initial conditions that are necessary for the passive gait of this bipedal robot on a sloping surface are *** effects of the characteristic parameters of elastic links including the modulus of elasticity and the Kelvin-Voigt coefficient on the walking stability of this type of

关键词： bipedal robot flexible link swing phase transient phase eigenvalue problem Kelvin-Voigt coefficient

Holographic dark energy in non-conserved gravity theory

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Communications in Theoretical Physics 2024年第4期76卷 126-133页

作者： H r Fazlollahi Institute of Gravitation and Cosmology Peoples Friendship University of Russia(RUDN University)6 Miklukho-Maklaya StMoscow117198Russia

recently, reconsidering the rastall idea T_(μ;νν)^(v)=α_(,μ) through relativistic thermodynamics gives a new form for the scalar field α which led us to construct modern modified theory of gravity debugged ‘non-conserved gravity theory’ Fazlollahi 2023 Euro. Phys. J. C 83 923. This theory unlike other modified theories of gravity cannot directly explain the current acceleration expansion in the absence of the cosmological constant and or existence of other forms of dark energy. Hence, in this study we have reinvestigated holographic dark energy Ρ_(X)~H^(2) in the non-conserved theory of gravity. In this context, the density and pressure of dark energy depend on the non-conserved term and density of the dust matter field. As shown, due to non-conservation effects on large-scale structures, unlike the original holographic model, our model onsets an acceleration epoch for the current Universe satisfies observations. Moreover, the interaction and viscous scenarios are studied for this model.

关键词： non-conserved gravity covariant form of thermodynamics holographic dark energy