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Two examples of surfaces with normal crossing singularities

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Science China Mathematics 2011年第8期54卷 1707-1712页

作者： KOLLr János Department of Mathematics Princeton University

This note gives two examples of surfaces with normal crossing *** the first example the canonical ring is not finitely *** the second,the canonical line bundle is not ample but its pull back to the normalization is *** latter answers in the negative a problem left unresolved in Ⅲ.2.6.2 of lments de gometrie algbrique,1961,and raised again by Viehweg.

关键词： singular surface canonical ring ampleness criteria

On f-Disjunctive Languages, f-Disjunctive Domains and Solid Codes(Dedicated to the late professor Xu Yonghua (1932-2019))

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Algebra Colloquium 2020年第2期27卷 331-342页

作者： Jing Leng Yuqi Guo K.p.Shum School of Mathematics and Statistics Lanzhou University Lanzhou 730000China Institute of Mathematics Yunnan University Kunming 650091China

Every language is either the disjoint union or the intersection of two disjunctive *** family of f-disjunctive languages is a natural generalization of the family of disjunctive *** domains(f-disjunctive domains)are defined as the languages which can be checked whether a given language is disjunctive(f-disjunctive)or *** f-disjunctive domains were first studied by Guo et *** *** continue their study on f-disjunctive *** new results for f-disjunctive domains,containing a relation between disjunctive domains and f-disjunctive domains,are *** this respect,we also make an appropriate opening for the completely dense languages and solid codes.

关键词： f-disjunctive languages f-disjunctive domains completely dense languages solid codes

Effects of feeding yeast(Saccharomyces cerevisiae), organic selenium and chromium mixed on growth performance and carcass traits of hair lambs

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Journal of Integrative Agriculture 2015年第3期14卷 575-582页

作者： pedro A Hernández-García Alejandro Lara-Bueno Germán D Mendoza-Martínez José r Bárcena-Gama Fernando X plata-pérez rufino López-Ordaz José A Martínez-García Faculty of Veterinary and Livestock (University Center) Autonomous University of the State of Mexico Department of Animal production Chapingo Autonomous University Department of Agriculture and Livestock Metropolitan Autonomous University (Xochimilco Unit) Institute of Genetic and productivity (Livestock Center) Postgraduate College

Yeasts and organic minerals are used in diets to improve health, productive performance and some carcass characteristics of ruminants and non-ruminants. Thirty-two lambs（pelibuey×Katahdin; BW=（30.55±1.67） kg; n=8） were used in a 56-d feeding experiment to study the effects of different levels of live yeast（Saccharomyces cerevisiae; yeast）, selenium（Se） and chromium（Cr） mixed（Se-Cr）, and a mixture of yeast-Se-Cr on growth performance and carcass traits. Animals were stratified by body weight（BW） and randomly assigned to one of four treatments： 1） control group（0.0 g kg–1 yeast）; 2） yeast（1.50 g kg–1 dry matter intake（DMI） d–1）; 3） Se-Cr premix（1.5 mg kg–1 DMI d–1 for each mineral）; and 4） yeast-Se-Cr mixture. There were no treatment effects on final BW; whereas lambs fed Se-Cr or yeast-Se-Cr had higher（p〈0.05） DMI than animals supplemented with only yeast. Average daily gain（ADG）, gain：feed ratio, chop area, dorsal fat and carcass yield were similar（p〉0.05） among treatment groups. In conclusion, supplementation with yeast, Se-Cr mixed or yeast-Se-Cr did not improve ADG, final BW, back fat content and carcass yield of growing of pelibuey×Katahdin lambs. Supplementation with Se-Cr and yeast-Se-Cr increased DMI, and approximately 250 g ADG animal–1 d–1 was produced with no negative effects on growth and health of the animals.

关键词： yeast organic selenium and chromium pelibuey×Katahdin sheep

On Almost Armendariz ring

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Algebra Colloquium 2020年第2期27卷 199-212页

作者： Om prakash Sushma Singh K.p.Shum Department of Mathematics Indian Institute of Technology Patna PatnaBihar 801106India Department of Mathematics John Fulton Center The Chinese University of Hong KongShatinN.T.Hong KongChina

In this paper,we introduce the notion of an almost Armendariz ring,which is a generalization of an Armendariz ring,and discuss some of its *** has been found that every almost Armendariz ring is weak Armendariz but the converse is not *** prove that a ring r is almost Armendariz if and only if r[x]is almost *** is also shown th at if r/I is an almost Armendariz ring and I is a semicommutative ideal,then H is an almost Armendariz ***,the class of minimal non-commutative almost Armendariz rings is completely determined,up to isomorphism(minimal means having smallest cardinality).

关键词： Armendariz ring almost Armendariz ring weak Armendariz ring lower nil radical reduced ring semicommutative ring

process parameters-weld bead geometry interactions and their influence on mechanical properties:A case of dissimilar aluminium alloy electron beam welds

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Defence Technology（防务技术） 2018年第2期14卷 137-150页

作者： p.Mastanaiah Abhay Sharma G.Madhusudhan reddy Defence research and Development Laboratory KanchanbaghHyderabadTelangana 500058India Indian Institute of Technology Hyderabad Kandi CampusSangareddyTelangana 502285India Defence Metallurgical research Laboratory KanchanbaghHyderabadTelangana 500058India

prediction of weld bead geometry is always an interesting and challenging research topic as it involves understanding of complex multi input and multi output system. The weld bead geometry has a profound impact on the load bearing capability of a weld joint, which in-turn decides the performance in real time service conditions. The present study introduces a novel approach of detecting a relationship between weld bead geometry and mechanical properties(e.g. tensile load) for the purpose of catering the best the process could offer. The significance of the proposed approach is demonstrated by a case of dissimilar aluminium alloy(AA2219 and AA5083) electron beam welds. A mathematical model of tensile braking load as a function of geometrical attributes of weld bead geometry is presented. The results of investigation suggests the effective thickness of weld-a geometric parameter of weld bead has the most significant influence on tensile breaking load of dissimilar weld joint. The observations on bead geometry and the mechanical properties(microhardness, ultimate tensile load and face bend angle) are correlated with detailed metallurgical analysis. The fusion zone of dissimilar electron beam weld has finer grain size with a moderate evaporation and segregation of alloying elements magnesium and copper *** mechanical properties of weld joint are controlled by optimum bead geometry and HAZ softening in weaker AA5083 Al alloy.

关键词： Electron beam welding AA2219 AA5083 Bead geometry Tensile breaking load

Nitrogen in Chinese coals

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Chinese Journal Of Geochemistry 2011年第2期30卷 248-254页

作者： Finkelman r.B. U.S.Geological Survey Mail Stop 956VA 20192USA

Three hundred and six coal samples were taken from main coal mines of twenty-six provinces,autonomous regions,and municipalities in China,according to the resource distribution and coal-forming periods as well as the coal ranks and coal *** was determined by using the Kjeldahl method at *** Survey(USGS),which exhibit a normal frequency *** nitrogen contents of over 90% Chinese coal vary from 0.52% to 1.41% and the average nitrogen content is recommended to be 0.98%.Nitrogen in coal exists primarily in organic *** is a slight positive relationship between nitrogen content and coal ranking.

关键词： coal nitrogen distribution

Low-tension gas process in high-salinity and low-permeability reservoirs

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petroleum Science 2020年第5期17卷 1329-1344页

作者： Alolika Das Nhut Nguyen Quoc p.Nguyen Hildebrand Department of petroleum and Geosystems Engineering University of Texas at Austin200 E.Dean KeetonAustinTX 78712USA

polymer-based EOr methods in low-permeability reservoirs face injectivity issues and increased fracturing due to near wellbore plugging,as well as high-pressure gradients in these *** may cause pore blockage and undergo shear degradation and even oxidative degradation at high temperatures in the presence of very hard ***-tension gas(LTG) flooding has the potential to be applied successfully for low-permeability carbonate reservoirs even in the presence of high formation brine *** LTG flooding,the interfacial tension between oil and water is reduced to ultra-low values(10^-3 dyne/cm) by injecting an optimized surfactant formulation to maximize mobilization of residual oil ***(nitrogen,hydrocarbon gases or C02) is co-injected along with the surfactant slug to generate in situ foam which reduces the mobility ratio between the displaced(oil) and displacing phases,thus improving the displacement efficiency of the *** this work,the mechanism governing LTG flooding in low-permeability,high-salinity reservoirs was studied at a microscopic level using microemulsion properties and on a macroscopic scale by laboratory-scale coreflooding *** main injection parameters studied were injected slug salinity and the interrelation between surfactant concentration and injected foam quality,and how they influence oil mobilization and displacement *** assessment of the results was performed by studying oil recovery,oil fractional flow,oil bank breakthrough and effluent salinity and pressure drop characteristics.

关键词： Enhanced oil recovery Foam Microemulsion Carbonate High salinity Low permeability

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江汉和泌阳盆地中卟啉化合物的分布

石油与天然气地质 1991年第2期12卷 136-142页

作者：陈军红傅家谟盛国英 r.p.philp 中国科学院地球化学研究所广州分部 School of Geology and Geophysics University of Oklahoma U.S.A.

卟啉化合物在江汉、泌阳两盆地中的分布,受沉积环境及热成熟作用的控制。五元侧环上具有甲基的C_(32),C_(33)DpEp卟啉异构体在石油中的高丰度指示了一种出现在较高盐度环境中特殊生源前体以及低成熟度。在热成熟作用下,卟啉化合物的主... 详细信息

卟啉化合物在江汉、泌阳两盆地中的分布,受沉积环境及热成熟作用的控制。五元侧环上具有甲基的C_(32),C_(33)DpEp卟啉异构体在石油中的高丰度指示了一种出现在较高盐度环境中特殊生源前体以及低成熟度。在热成熟作用下,卟啉化合物的主要变化为DpEp的逐渐消失及ETIO中脱烷基及烷基化作用。DpEp/ETIO或DpEp/(DpEp+ETIO),C_(31)ETIO-A/C_(28)ETIO-B及ETIO-AC_(31)/C_(30)等比值可用作热成熟度指标。

关键词：盆地卟啉液相色谱石油

Assessing tourism sustainability in hill towns:Case study of Shimla,India

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Journal of Mountain Science 2020年第9期17卷 2241-2261页

作者： rukhsana N.BADAr Sarika p.BAHADUrE Department of Architecture and planning Visvesvaraya National Institute of TechnologySouth Ambazari RoadNagpur 440010MaharashtraIndia

Hill towns form a popular niche in tourism *** are renowned for their natural beauty and distinctive cultural *** development can lead to a loss in opportunity to access the potential of these resources or cause their *** decisions need to adopt a sustainable approach that balances tourism growth with the preservation of the natural and cultural *** present research details a comprehensive assessment tool to study the sustainability of tourism in hill towns with a focus on Shimla,a popular hill destination in *** tool specifies seven dimensions of sustainable tourism;1)Tourism Assets;2)Tourism Activity;3)Tourism related Linkages;4)Tourism related Leakages;5)Environmental and Social Sustainability;6)Infrastructure;and 7)*** data were collected through questionnaire surveys of local households and arriving *** survey is conducted to map built-environment and *** data were gathered from government reports and scholarly articles.A framework of indicators and sub-indicators was developed to analyze the data at two levels–city and *** the appraisal of the city provides an overall view of the performance of the tourism industry,at the ward level a comparative analysis was carried out to reveal sector related potentials and *** study reveals the imbalanced tourismconcentration in the core of the city as compared to other wards and the gap between tourist potential and infrastructure *** are addressed through planning recommendations for more balanced development with a focus on *** research helps develop a framework which paves way to sustainable tourism development in Indian hill towns.

关键词： Sustainable tourism Hill towns Tourism assets Tourism linkages Tourism leakages