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Performance evaluation of minimum quantity lubrication by vege-table oil in terms of cutting force,cutting zone temperature,tool wear,job dimension and surface finish in turning AISI-1060 steel

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第11期7卷 1790-1799页

作者： KHAn M.M.A. dhar n.R. Department of Industrial and Production Engineering Shahajalal University of Science and Technology Sylhet 3114 Bangladesh Department of Industrial and Production Engineering Bangladesh University of Engineering and Technology (BUET) Dhaka Bangladesh

In all machining processes, tool wear is a natural phenomenon and it leads to tool failure. The growing demands for high productivity of machining need use of high cutting velocity and feed rate. Such machining inherently produces high cutting temperature, which not only reduces tool life but also impairs the product quality. Metal cutting fluid changes the performance of machining operations because of their lubrication, cooling and chip flushing functions, but the use of cutting fluid has become more problematic in terms of both employee health and environmental pollution. The minimization of cutting fluid also leads to economical benefits by way of saving lubricant costs and workpiece/tool/machine cleaning cycle time. The concept of minimum quantity lubrication (MQL) has been suggested since a decade ago as a means of addressing the issues of environmental intru- siveness and occupational hazards associated with the airborne cutting fluid particles on factory shop floors. This paper deals with experimental investigation on the role of MQL by vegetable oil on cutting temperature, tool wear, surface roughness and dimen- sional deviation in turning AISI-1060 steel at industrial speed-feed combinations by uncoated carbide insert. The encouraging results include significant reduction in tool wear rate, dimensional inaccuracy and surface roughness by MQL mainly through reduction in the cutting zone temperature and favorable change in the chip-tool and work-tool interaction.

关键词： Minimum quantity lubrication (MQL) Cutting force Chip-tool interface temperature Tool wear Surface roughness Dimensional deviation

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Fracture Toughness and Microcracks on natural Apophyllite Crystals

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Journal of Materials Science & Technology 1998年第2期14卷 156-160页

作者： dhar, P.R. Bamzai, K. Kotru, P.n. Dept. of Physics University of Jammu Jammu-180004 India

Results on fracture toughness of natural apophyllite crystals when they were subjected to impact were presented. The morphology of the cracks and fracture has been studied. It was found that the crack formation does not show any anisotropic property and remains the same whatever may be the orientation of the crystal. The average values of the fracture toughness K//c and brittleness index, as determined from measurements of crack length, were estimated to be 0.107 g mu m** minus **3**/**2 and 4.19 mu m** minus **1**/**2 respectively for the a(100) plane. The yield strength for a(100), P(111) and C(001) planes of apophyllite crystals for lower loads is 2250, 2160 and 1840 MPa and for higher loads is 1510, 1600 and 1430 MPa respectively. (Edited author abstract) 7 Refs.

关键词： Crystals

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Climate-driven variations in productivity reveal adaptive strategies in Iberian cork oak agroforestry systems

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Forest Ecosystems 2022年第1期9卷 83-93页

作者： José Carlos Pérez-girón Emilio Rafael Díaz-Varela Pedro Álvarez-Álvarez Department of Organisms and Systems Biology Polytechnic School of MieresUniversity of OviedoE-33600MieresAsturiasSpain Research Group on Planning and Management in Complex Adaptive Socio-Ecological Systems(COMPASSES).School of Engineering University of Santiago de CompostelaE-27002LugoSpain

Background:Cork oak agroforestry systems(AFS)have been managed for centuries by humans to produce cork and other goods and services and have recently been recognised as an important reservoir for biodiversity improvement and ***,despite having recently been included as a natural habitat of community-wide interest within the EU Habitats Directive,these systems are in a critical situation of *** other factors,they are strongly threatened by climate change,the effects of which are also expected to be particularly severe in the Mediterranean *** this study,we aimed to evaluate the influence of climate variability by examining primary production indicators and also to analyse whether the geographical location may have a role in the incidence of the adverse effects of ***:Cork oak AFS were identified in the Forest Map of Spain and the Land use map of Portugal and categorized on the basis of canopy *** climate data from 2001 to 2020 were used to model relationships with climate predictors and proximity to the *** analysis was conducted to identify significant spatial clusters of high-and low-efficiency ***:The responses to the influence of climatic conditions differed among the various cork oak AFS categories,particularly in the forest category,which was less dependent on climate *** humidity and water availability were the main drivers of net primary production(nPP).Carbon use efficiency(CUE)was limited by relative humidity and spring temperature in open *** to the coast proved beneficial,especially in years with adverse weather conditions,but was not a limiting factor for survival of the ***,the results of the hotspot analysis supported the other findings,highlighting high-efficiency areas close to the coast and cold spots grouped in specific areas or dispersed ***:Canopy plays a key role in the influence of climatic conditions,particu

关键词： net primary production Carbon use efficiency Climate Quercus suber Agroforestry system

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Impact of the non-indigenous shrub species Spartium junceum (Fabaceae) on native vegetation in central Spain

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Journal of Plant Ecology 2016年第2期9卷 132-143页

作者： Rosario G.Gavilán Daniel Sánchez-Mata Mylena Gaudencio Alba Gutiérrez-girón Beatriz Vilches Departamento de Biología Vegetal II Facultad de FarmaciaUniversidad ComplutensePlaza de Ramón y Cajal s/nE-28040 MadridSpain

Aims The introduction of potentially invasive species through ornamental cultivation or for rehabilitation purposes is a serious environmental *** cause damage to biodiversity through loss,increased mortality or‘in situ’selection phenomena in natural *** junceum is a Mediterranean shrub that is not native in most areas of the Iberian Peninsula,although it is extensively grown for the rehabilitation of *** have investigated the effect on the native vegetation of an old ***(Fabaceae)plantation in a conservation area in the centre of the Iberian Peninsula:the Cuenca Alta del Manzanares nature reserve in *** We compared *** stands with the native nanophanerophytic Cistus ladanifer community at different ecosystem properties:soil properties,temporal soil seed bank contents,standing vegetation and net primary production of annual grasslands growing in these *** Findings The results highlighted ***’s ability to become established in the new environment(marginal areas of the nature reserve)and ensure its successful *** is more apparent in northern and eastern exposures where this formation contacts with the core of the best conserved native vegetation in the nature *** under Spartium showed a higher nitrogen content,indicating its capacity-in common with other legumes-to fix n,and conferring an advantage over Cistus,which is *** soil nutrients such as phosphorus,magnesium and calcium and water availability are also higher in Spartium soils than in *** is usually a constraint for n-fixers,but in our study,it is the most significant soil variable in both shrub formations and is important to the success of *** availability is a key factor for Mediterranean vegetation,and particularly in autumn when soils are *** Spartium formation is able to retain water as its growth produces a closer canopy than Cistus,thereby preventing water evaporatio

关键词： Cistus ladanifer community structure old fields invasive species Mediterranean plant communities non-native species soil seed bank shrublands rehabilitation practices

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First-principles calculations to investigate structural,electronic,magnetic,optical and thermodynamic properties of RE_(2)Rh_(3)Ge(RE=Pr,Sm)

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Journal of Rare Earths 2024年第7期42卷 1385-1393,I0007页

作者： A.Ezaier R.Masrour M.Hamedoun J.Kharbach A.Rezzouk A.Hourmatallah n.Benzakour K.Bouslykhane Laboratory of Solid Physics Faculty of Sciences Dhar El MehrazSidi Mohamed Ben Abdellah UniversityBP 1796FezMorocco Equipe de Physique du Solide LaboratoiresLIPIEcole Normale SupérieureBensoudaFèsMorocco

In this paper,we analyzed the physical characteristics of the ternary alloys RE_(2)Rh_(3)Ge(RE=Pr and Sm)using the first principles calculation based on functional density theory integrated in the Wien2k *** calculated formation energies of Pr_(2)Rh_(3)Ge and Sm_(2)Rh_(3)Ge are−5.3827 and−5.2782 eV/atom,respectively,showing that these alloys may exist *** results of the band structure and density of states indicate that all of the compounds tested are magnetic metals,and their magnetism is mostly related to the contribution of Pr and Sm *** total magnetic moments of Pr_(2)Rh_(3)Ge and Sm_(2)Rh_(3)Ge are 4.07245 and 11.16161μB/f.u,*** parameters such as heat capacity at constant pressure,entropy,Debye temperature,lattice volume,compressibility coefficients,and Grüneisen parameter alloys were calculated using the Gibbs algorithm and studied in depth over a large temperature range of 0-900 *** Debye temperature increases with increasing pressure and decreases with decreasing ***,the Debye temperatures calculated at p=0 GPa and T=300 K are equal to be 342 and 322 K for Pr_(2)Rh_(3)Ge and Sm_(2)Rh_(3)Ge,*** optical characteristics such as the real and imaginary portions of the dielectric function,the absorption coefficient,the energy-loss function,and the refractive index were investigated and discussed in more depth.

关键词： Magnetic metals Functional density theory Density of states Magnetic moment Optical and thermodynamic properties Rare earths

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A state-of-the-art review on geothermal energy exploration in Morocco: Current status and prospects

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Deep Underground Science and Engineering 2024年第3期3卷 302-316页

作者： Redouane Meryem Khalis Hind Haissen Faouziya Sadki Othman Berkat n.Eddine Raji Mohammed Faculty of Sciences Ben M'sick CasablancaMorocco Faculty of Sciences dhar El Mahraz FezMorocco national Office of Hydrocarbons and Mines RabatMorocco

In the last few decades, addressing the global challenge of implementation of strategies for renewable energy and energy efficiency has become ***, since 2009, has made a steadfast commitment to sustainability, with a particular focus on advancing the development of renewable energy resources. A comprehensive strategy has been formulated, centering on utilizing the country's energy potential to drive progress in this vital sector. Morocco is considered a country with abundant thermal water, indicating deep reservoirs with significant hydrothermal potential. Geothermal zones were selected based on the abundance of hot springs where water temperatures were high and geothermal gradients were significant. The abundance and importance of hot springs, combined with recent volcanism and ongoing non-tectonic activity linked to alpine orogeny, strongly suggest that these regions are promising reservoirs for geothermal energy. This great potential also extends to neighboring countries. In northeast and south Morocco, the temperature of thermal water ranges from 26 to 54℃. This study serves as an inclusive review of the geothermal potentialities in Morocco.

关键词： geothermal gradients hot springs hydrothermal potential Morocco renewable energy sustainability

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Correlation among extinction efficiency and other parameters in an aggregate dust model

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Research in Astronomy and Astrophysics 2017年第11期17卷 95-112页

作者： Tanuj Kumar dhar Himadri Sekhar Das Department of Physics Assam University Silchar 788011 India

We study the extinction properties of highly porous Ballistic Cluster-Cluster Aggregate dust aggregates in a wide range of complex refractive indices （1.4 ≤ n 〈 2.0, 0.001 ≤ k 〈 1.0） and wavelengths （0.11 μm 〈 A 〈 3.4 μm）. An attempt has been made for the first time to investigate the correlation among extinction efficiency （Qext）, composition of dust aggregates （n, k）, wavelength of radiation （A） and size parameter of the monomers （x）. If k is fixed at any value between 0.001 and 1.0, Qext increases with increase of n from 1.4 to 2.0. Qext and n are correlated via linear regression when the cluster size is small, whereas the correlation is quadratic at moderate and higher sizes of the cluster. This feature is observed at all wavelengths （ultraviolet to optical to infrared）. We also find that the variation of Qext with n is very small when A is high. When n is fixed at any value between 1.4 and 2.0, it is observed that Qext and k are correlated via a polynomial regression equation （of degree 1, 2, 3 or 4）, where the degree of the equation depends on the cluster size, n and A. The correlation is linear for small size and quadratic/cubic/quartic for moderate and higher sizes. We have also found that Qext and x are correlated via a polynomial regression （of degree 3, 4 or 5） for all values of n. The degree of regression is found to be n and k-dependent. The set of relations obtained from our work can be used to model interstellar extinction for dust aggregates in a wide range of wavelengths and complex refractive indices.

关键词： light scattering -- ISM: dust extinction

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Efficiency of Severe Recorded Rainstorms over Maharashtra State

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Advances in Atmospheric Sciences 1995年第1期12卷 103-108页

作者： B.D.Kulkarni Miss Shobha nandargi O. n. dhar Indian Institute of Tropical Meteorology Pune -411 008 India Indian Institute of Tropical Meteorology Pune -411 008 India Indian Institute of Tropical Meteorology Pune -411 008 India

12 severe rainstorms have been experienced by different meteorological sub-divisions of Maharashtra State during the last 100-year period from 1891-1990. For each of the rainstorms efficiency factors (i.e. P/ M ratios) were worked out for maximum one-day duration and for three standard areas of 1000, 5000, and 10,000 km2. Comparison of these ratios with the past has shown that the most efficient rainstorm over Maharashtra was the rainstorm of June, 1908 over the Vidarbha region whose full DAD data as well as isohyetal pattern have been given.

关键词： Rainstonn Depth-area -duration (DAD) Efficiency factor of rainstorms Probable Maximum Precipitation (PMP)

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Citric acid:An efficient and green catalyst for rapid one pot synthesis of quinoxaline derivatives at room temperature

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Chinese Chemical Letters 2011年第4期22卷 389-392页

作者： Radhakrishnan Mahesh Arghya Kusum dhar Tara Sasank T.V.n.V. Sappanimuthu Thirunavukkarasu Thangaraj Devadoss Birla Institute of Technology & Science PilaniRajasthan-333031India Orchid Chemicals and Pharmaceutical Ltd. SholinganallurChennai-600119India

The condensation of o-phenylenediamines with 1,2-dicarbonyl compounds in the presence of citric acid afforded the corresponding quinoxaline derivatives in higher yields at room temperature in ethanol,and most of the r... 详细信息

关键词： Quinoxalins Citric acid o-Phenylenediamines 1 2-Dicarbonyl compounds Green catalyst

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Prolonged impacts of COVID-19-associated cystitis:A study on longterm consequences

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World Journal of Clinical Cases 2023年第33期11卷 7987-7993页

作者： Sophie Wittenberg Jack Vercnocke Michael Chancellor Sorabh dhar Aron Liaw Steven Lucas nivedita dhar Department of Urology Wayne State University School of MedicineDetroitMI 48201United States Department of Urology Beaumont HospitalRoyal OakMI 48067United States Infectious Disease Wayne State University School of MedicineDetroitMI 48201United States Infectious Disease John D.Dingell VA Medical CenterDetroitMI 48201United States Infectious Disease Detroit Medical CenterDetroitMI 48201United States Department of Urology John D.Dingell VA Medical CenterDetroitMI 48201United States Department of Urology Detroit Medical CenterDetroitMI 48201United States

BACKGROUnD The Coronavirus Disease 2019(COVID-19)caused by the severe acute respiratory syndrome coronavirus 2 virus is an international health concern with substantial morbidity and ***-associated cystitis(CAC),presents as new onset or exacerbated urinary symptoms,resembling overactive bladder(OAB)*** To examines the long-term outcomes of patients with CAC in the context of Long *** A cohort of 350 patients admitted to Detroit Hospitals with COVID-19 between May and December 2020,displaying CAC symptoms following discharge,was prospectively *** urologic evaluations occurred at 10-14 wk and were repeated at 21-28 mo *** were managed conservatively,employing behavioral modifications and standard OAB *** completed surveys assessing urinary symptoms and quality of life(QoL)at both time *** primary outcome was the Urology Care Foundation Overactive Bladder Assessment *** 87%of the final cohort(n=310)reported symptom improvement at 21-28 mo *** with new onset CAC symptoms showed a median decrease of 9-10 points in OAB and QoL scores,while those with existing symptoms experienced a decrease of 6 ***,95.4%of patients with new onset symptoms reported symptom improvement at follow-up,contrasting with 60.7%among those with existing *** This study presents the first long-term follow-up of adult patients with CAC,revealing a promising prognosis with conservative management measures in the context of Long *** findings provide reassurance to patients regarding symptom resolution and underscore the need for further research into this evolving aspect of COVID-19's impact on urological health.

关键词： COVID associated cystitis COVID-19 Long COVID Overactive bladder

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