检索结果-南通市图书馆

Correcting distortions of thin-walled machined parts by machine hammer peening

Chinese Journal of Aeronautics 2024年第6期37卷 439-453页

作者： Aitor MADARIAGA Mikel CUESTA Gorka ORTIZ-DE-ZARATE Eneko SAENZ-DE-ARGANDONA Denis SORIANO micha.l b.prime Pedro Jose ARRAZOlA Department of Materials University of ManchesterOxford RoadManchester M139PLUnited Kingdom Mechanical and Industrial Production Department Faculty of EngineeringMondragon UnibertsitateaArrasate 20500Spain los Alamos National laboratory Los AlamosNew MexicoUSA

Thin-walled aerostructural components frequently get distorted after the machining *** to correct distortions or eventually rejecting parts significantly increases the *** paper proposes a new approach to correct distortions in thin-walled components by strategically applying hammer peening on target surfaces of a machined *** alloy 7475-T7351 was chosen for this *** study was divided in two ***,the residual stresses(RS)induced by four different pneumatic hammer peening conditions(modifying the stepover distance and initial offset)were characterised in a test coupon,and one of the conditions was selected for the next *** the second stage,a FEM model was used to predict distortions caused by machining in a representative ***,the RS induced by hammer peening were included in an FEM model to define two hammer peening strategies(varying the coverage area)to analyse the capability to reduce *** workpieces were machined and then treated with the simulated hammer peening strategies for experimental *** in the test coupon showed that pneumatic hammer peening can generate high compressive RS(-50 to350 MPa)up to 800 lm depth,with their magnitude increasing with a reduced stepover *** of hammer peening over 4% of the surface of the representative workpiece reduced the machininginduced distortions by 37%,and a coverage area of 100% led to and overcorrection by a factor of *** confirms that hammer peening can be strategically applied(in target areas and changing the percentage of coverage)to correct low or severe distortions.

关键词： Aeronautics Machining,Hammer Peening Aluminium alloy Distortions Residual Stress

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Utilizing FDI to Stay Ahead:The Case of Singapore

Utilizing FDI to Stay Ahead:The Case of Singapore

引用

北京论坛（2011）文明的和谐与共同繁荣--传统与现代、变革与转型

作者： Penelope b.prime Mercer University

A small country with 4.99 million people in a 710.3 square km area,Singapore has built itself into an integral part of global markets with living standards that are some of the highest in the *** purpose of this paper is to understand this experience in the context of a capabilities-based framework to explore how Singapore has done so well,especially as a small, resource-scarce country dependent on global markets. The thesis argued is that at the core of Singapore's overall success has been the strengthening of domestic social capabilities that were continuously updated and expanded to meet the needs of foreign *** policies were hyper-sensitive to providing the conditions for foreign firms to be *** firms invested in Singapore and by now have helped close not only the income gap with advanced economies but is on its way to closing the innovation *** Singapore case demonstrates that with deliberate attention to building skills,institutions and infrastructure,it is possible for a small country to upgrade skills and to move up the production value chain with primary reliance on *** of private Singaporean firms has been *** to the future,this may be the next step needed to sustain progress.

关键词： Utilizing FDI to Stay Ahead:The Case of Singapore FDI

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

On the Number of primes in the Interval (x, 2x) by an Elementary Method

引用

Advances in Pure Mathematics 2024年第1期14卷 16-29页

作者： Sudhindra b. Kittur Independent Researcher Mumbai India

An elementary formula to know the number of primes in the interval (x, 2x) close to the exact figure for a fixed x is given here. A new elementary equation is derived (a relation between prime numbers and composite numbers distributed in the interval [1, 2x]). An elementary method to know the number of primes in a given magnitude is suitably placed in the form of a general formula, and we have proved it. The general formula is applied to the terms of the equation, and a tactical simplification of the terms gives rise to an expression whose verification envisages scope for its further studies.

关键词： prime Numbers Composite Numbers Expression Integers

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

A New Proof for Congruent Number’s Problem via Pythagorician Divisors

引用

Advances in Pure Mathematics 2024年第4期14卷 283-302页

作者： léopold Dèkpassi Keuméan François Emmanuel Tanoé UFR Mathematics and Computer Science F&#233lix Houphou&#235t Boigny University Abidjan Cote d&#8217Ivoire

Considering Pythagorician divisors theory which leads to a new parameterization, for Pythagorician triplets ( a,b,c )∈ ℕ 3∗ , we give a new proof of the well-known problem of these particular squareless numbers n∈ ℕ ∗ , called congruent numbers, characterized by the fact that there exists a right-angled triangle with rational sides: ( A α ) 2 + ( b β ) 2 = ( C γ ) 2 , such that its area Δ= 1 2 A α b β =n;or in an equivalent way, to that of the existence of numbers U 2 , V 2 , W 2 ∈ ℚ 2∗ that are in an arithmetic progression of reason n;Problem equivalent to the existence of: ( a,b,c )∈ ℕ 3∗ prime in pairs, and f∈ ℕ ∗ , such that: ( a−b 2f ) 2 , ( c 2f ) 2 , ( a+b 2f ) 2 are in an arithmetic progression of reason n;And this problem is also equivalent to that of the existence of a non-trivial primitive integer right-angled triangle: a 2 + b 2 = c 2 , such that its area Δ= 1 2 ab=n f 2 , where f∈ ℕ ∗ , and this last equation can be written as follows, when using Pythagorician divisors: (1) Δ= 1 2 ab= 2 S−1 d e ¯ ( d+ 2 S−1 e ¯ )( d+ 2 S e ¯ )=n f 2;Where ( d, e ¯ )∈ ( 2ℕ+1 ) 2 such that gcd( d, e ¯ )=1 and S∈ ℕ ∗ , where 2 S−1 , d, e ¯ , d+ 2 S−1 e ¯ , d+ 2 S e ¯ , are pairwise prime quantities (these parameters are coming from Pythagorician divisors). When n=1 , it is the case of the famous impossible problem of the integer right-angled triangle area to be a square, solved by Fermat at his time, by his famous method of infinite descent. We propose in this article a new direct proof for the numbers n=1 (resp. n=2 ) to be non-congruent numbers, based on an particular induction method of resolution of Equation (1) (note that this method is efficient too for general case of prime numbers n=p≡a ( ( mod8 ) , gcd( a,8 )=1 ). To prove it, we use a classical proof by induction on k , that shows the non-solvability property of any of the following systems ( t=0 , corresponding to case n=1 (resp. t=1 , corresponding to case n=2 )): ( Ξ t,k ){ X 2 + 2 t ( 2 k Y ) 2 = Z 2 X 2 + 2

关键词： prime Numbers-Diophantine Equations of Degree 2 & 4 Factorization Greater Common Divisor Pythagoras Equation Pythagorician Triplets Congruent Numbers Inductive Demonstration Method Infinite Descent bSD Conjecture

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Fluoride contamination in groundwater:A global review of the status,processes,challenges,and remedial measures

引用

Geoscience Frontiers 2024年第2期15卷 1-29页

作者： E.Shaji K.V.Sarath M.Santosh P.K.Krishnaprasad b.K.Arya Manisha S.babu Department of Geology University of KeralaKariavattom CampusThiruvananthapuramKerala 695581India School of Earth Sciences and Resources China University of Geosciences(Beijing)29 Xueyuan RoadBeijing 100083China Department of Earth Science University of AdelaideAdelaideSA 5005Australia Department of Geology Central University of KeralaTejaswini HillsPeriyeKasaragodKerala 671316India

Groundwater pollution by fluoride is one of the prime concerns of the world population due to its toxicity,which results in adverse health *** this paper,we review the current scenario of the fluoride contamination of groundwater in various countries across the globe and its impact on human *** the last decade,several newly affected regions have been reported all over the world,with more than 100 countries affected by fluoride contamination in groundwater(concentration exceeding the acceptable limit of 1.5 mg/l defined by the World Health Organization).Fluoride poisoning is mainly due to the unsupervised ingestion of products for dental and oral hygiene and over-fluoridated drinking *** is estimated that more than 200 million people from different countries are affected by fluoriderelated groundwater issues and health *** highest among these are from the countries in Africa(38),Asia(28),and Europe(24),followed by countries like South America(5),North America(3),and Australia(2).The source of fluoride in drinking water is primarily geogenic,together with forage,grasses and grains,tea,and anthropogenic *** countries affected were correlated with climatic zones and geological factors to gain insights into geospatial *** analyses show that most of the fluoride pollution-prone zones are located in high-grade metamorphic terranes with granitoid or alkaline intrusions,geothermal hot springs,and volcanic regions with arid or semi-arid climatic *** study also finds that children across the globe are more vulnerable than adults to fluoride *** review finds that,although there are efficient fluoride removal techniques,including filters with next-generation nanomaterials,to date,there has not been a single technique developed that can claim to be a practically robust solution for fluoride removal from drinking ***,we suggest developing next-generation filters that can retain essential miner

关键词： Fluoride Groundwater Water contamination WHO standards Climate zones Remediation Sustainable Development Goals

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Consequence of exponential heat generation on non-Darcy- Forchheimer flow of water based carbon nanotubes driven by a curved stretching sheet

引用

Applied Mathematics and Mechanics(English Edition) 2020年第11期41卷 1723-1734页

作者： b.J.GIREESHA b.NAGARAJA S.SINDHU G.SOWMYA Department of P.G.Studies and Research in Mathematics Kuvempu UniversityShankaraghatta 577451India

The present article comprises the study on the influence of exponential space based heat generation on the non-Darcy-Forchheimer flow of carbon nanotubes(CNTs).The flow is considered over a curved stretching *** variables are used to reduce the flow descriptive nonlinear partial derivative equations to simple *** equations are then solved by the exploiting Runge-Kutta-Fehlberg fourth-and fifth-order *** numerical solutions are shown in graphs and *** between single and multi-walled CNTs has been established through the tabulated values and plotted *** is concluded that the heat source parameter plays a prime role in enhancement of temperature,and the curvature parameter has adverse impact on velocity and temperature *** the inertial parameter and inverse-Darcy number affect the fluid velocity.

关键词： exponential heat generation non-Darcy-Forchheimer flow carbon nanotube(CNT) curved stretching sheet

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Effect of a semi electro-mechanical engine valve on performance and emissions in a single cylinder spark ignited engine

引用

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2010年第2期11卷 106-114页

作者： bülent ZDAlYAN Oguzhan DOGAN Department of Automotive Education Karabuk UniversityKarabuk 78050Turkey

In this study, an electro-mechanical valve （EMV） system for the intake valve ofa fottr stroke, single cylinder, overhead valve and spark ignition （SI） engine was designed and constructed. An engine with the EMV system and a standard engine were tested to observe the effects of the EMV on engine performance and emissions at different speeds under full load. The EMV engine showed improved engine power, engine torque and break specific fuel consumption （bSFC）. A 66% decrease in CO emissions was also obtained with the EMV system, but hydrocarbons （HC） and NOx emissions increased by 12% and 13% respectively.

关键词： Semi electro-mechanic Camless engine Electro-mechanic engine valve Engine performance Emissions

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Waring-Goldbach Problem: One Square and Nine biquadrates

引用

Chinese Annals of Mathematics,Series b 2019年第2期40卷 273-284页

作者： Xiaodong lü Yingchun CAI School of Mathematical Science Yangzhou University Department of Mathematics Tongji University

In this paper it is proved that every sufficiently large even integer N satisfying one of the congruence conditions N ≡ 10, 58, 130, or 178(mod 240) may be represented as the sum of one square and nine fourth powers ... 详细信息

关键词： Waring-Goldbach problem Hardy-littlewood method

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Sifting for small primes from an arithmetic progression

引用

Science China Mathematics 2023年第12期66卷 2715-2730页

作者： John b.Friedlander Henryk Iwaniec Department of Mathematics University of TorontoTorontoON M5S 2E4Canada Department of Mathematics Rutgers UniversityPiscatawayNJ 08903USA

In this work and its sister paper(Friedlander and Iwaniec(2023)),we give a new proof of the famous linnik theorem bounding the least prime in an arithmetic *** sieve machinery in both papers,we are able to dispensh with the log-free zero density bounds and the repulsion property of exceptional zeros,two deep innovations begun by linnik and relied on in earlier proofs.

关键词： sieve small primes linnik theorem

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

OD-Characterization of certain four dimensional linear groups with related results concerning degree patterns

引用

Frontiers of Mathematics in China 2015年第1期10卷 1-31页

作者： b. AKbARI A.R. MOGHADDAMFAR Department of Mathematics K. N. Toosi University of Technology P. O. Box 16315-1618 Tehran Iran Research Institute for Fundamental Sciences Tabriz Iran

The prime graph of a finite group G, which is denoted by GK（G）, is a simple graph whose vertex set is comprised of the prime divisors of ｜G｜ and two distinct prime divisors p and q are joined by an edge if and only if there exists an element of order pq in G. let P1 〈 P2 〈 … 〈 Pk be all prime divisors of ｜G｜- Then the degree pattern of G is defined as D（G） = （degG（pl）, degG（p2）,..., degG（pk））, where degG（p） signifies the degree of the vertex p in GK（G）. A finite group H is said to be OD-characterizable if G ≌ H for every finite group G such that ｜G｜ = ｜H｜and D（G） = D（H）. The purpose of this article is threefold. First, it finds sharp upper and lower bounds on v（G）, the sum of degrees of all vertices in GK（G）, for any finite group G （Theorem 2.1）. Second, it provides the degree of vertices 2 and the characteristic p of the base field of any finite simple group of lie type in their prime graphs （Propositions 3.1-3.7）. Third, it proves the linear groups l4（q）, q = 19, 23, 27, 29, 31, 32, and 37, are OD-characterizable （Theorem 4.2）.

关键词： prime graph degree pattern simple group

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：