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Search Results: 1 - 10 of 14377 matches for " stress –loops "
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Stress Loops Effect in Ductile Failure of Mild Steel  [PDF]
O.O. Oluwole
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2009, DOI: 10.4236/jmmce.2009.84026
Abstract: A simulation study of effect of stress on mild steel microstructure has revealed stress loops at areas of stress application which are believed to be the root cause of the ductile failure morphology (cup and cone) in ductile alloys under plane strain conditions. The areas of concentration of these stress loops were observed to be that of subsequent instability (or necking) observed in mild steel and other materials of low friction (flow) stress. Shear stress loops with angular bearing of 450 to the tensile axis were observed to instigate both the failure site and shear morphology in these materials. In plane stress conditions, shear was seen to be that of a wave shape running obliquely to area of stress application resulting in oblique necking observed in thin mild steel sheets.
Stress Effects on Microstructure and Failure Morphology of Low Carbon Steel Sheet
Nathaniel Onyeka ONURISI,Oluleke OLUWOLE
Leonardo Electronic Journal of Practices and Technologies , 2011,
Abstract: This paper presents experimental and simulation study of the effects of stress on microstructure and failure morphology of low carbon steel under plane stress conditions. The study has revealed large extension of grains at the point of fracture and, stress and strain looped around the pearlitic faces of the microstructure matrix. The stress and strain distributions in the microstructure have shown that concentration of stress and strain on the pearlite were instrumental to oblique fracture near the constrained region.
The Study on the Cycloids of Moving Loops  [PDF]
Gennady Tarabrin
Journal of Applied Mathematics and Physics (JAMP) , 2018, DOI: 10.4236/jamp.2018.64070
Abstract: The infinite set of cycloids is created. Each cycloid of this set is defined as a movement trajectory of a point when this point circulates on the convex closed contour of arbitrary form when this contour moves rectilinearly without rotation on the plane with a velocity equal to the tangential velocity of a point on circulation contour. The classical cycloid is elements of this set. The differential equation of a cycloid set is derived and its solution in quadratures is received. The inverse problem when for the given cycloid it is necessary to fine the form of a circulation contour is solved. The problem of differential equation of the second order with boundary conditions about a bend of big curvature of an elastic rod of infinite length is solved in quadratures. Geometry of the loop which is formed at such bend is investigated. It is discovered that at movement of an elastic loop on a rod when the form and the size of a loop don’t change, each point of a loop moves on a trajectory which named by us the cycloid and which represents a circumference arch.
Asas metálicas calibradas para microbiólogos: Una alternativa de fabricación nacional
Herrera,Dubraska; López,Patricia; Duque Rivera,José Luis; Pérez Ybarra,Luis; Golding,Rafael; Hernández,Clara;
Revista de la Sociedad Venezolana de Microbiología , 2010,
Abstract: calibrated metallic loops for the quantification of bacterial colony forming units transfer an ?exactly known? sample volume and have been extremely important tools for quality control, research and clinical laboratories. the loops marketed in our country are imported and mostly made of nickel-chrome alloy. this has created the need for searching for low cost national alternatives. in this work we propose the manufacture of these loops with commercial nickel-chrome wire equivalent to the commercial platinum and nickel-chrome loops, at lower costs. the loops were comparable in performance and appearance. all the loops were calibrated using two methods (gravimetric and colorimetric) with 45o and 90o charge angles. an experimental design with factorial treatment arrangement 23 (calibration method-loop type-charge angle with 4 repetitions) was used. a 672 data variance analysis and comparison of means (tukey?s test) were carried out, and bonferroni?s confidence intervals of the standard deviations were calculated. it was demonstrated that the artisan loops emulated the commercial ones, representing a low cost national alternative for obtaining these instruments.
Experimental study of temperature dependent deformation and degradation behaviour of PZT piezoelectric ceramics
PZT压电陶瓷高温变形与失效的实验研究

LI Ying-wei,ZHOU Xi-long,LI Fa-xin,
李应卫
,周锡龙,李法新

实验力学 , 2012,
Abstract: 随着工业设备集成化进程的加快,PZT压电陶瓷获得越来越广泛的应用,其工作环境也越来越复杂。例如,新一代节能环保型发动机中起致动作用的压电陶瓷叠层驱动器,工作时要承受力-热-电载荷的共同作用。因此,研究PZT压电陶瓷在高温下的变形与失效行为,对工业设计具有重要的指导意义。为此,本文利用自行搭建的压电陶瓷高温下电滞回线、蝶形回线和应力退极化曲线的测试装置,研究了PZT压电陶瓷在不同温度下的电致变形和应力退极化行为,得到了材料在不同温度下的电滞回线、蝶形回线、应力电位移曲线和应力应变曲线。实验结果表明,随着温度的升高,由电滞回线测得的剩余极化逐渐减小,蝶形回线逐渐变扁;由应力退极化产生的剩余极化和剩余应变也逐渐减小。极化量的改变是由材料的热释电效应(自发极化随温度的升高而减小)造成的,而应变量的变化是由晶胞畸变随着温度升高而减小所致。
On another two cryptographic identities in universal Osborn loops
T. G. Jaiyéolá,J. O. Adéníran
Surveys in Mathematics and its Applications , 2010,
Abstract: In this study, by establishing an identity for universal Osborn loops, two other identities (of degrees 4 and 6) are deduced from it and they are recognized and recommended for cryptography in a similar spirit in which the cross inverse property (of degree 2) has been used by Keedwell following the fact that it was observed that universal Osborn loops that do not have the 3-power associative property or weaker forms of; inverse property, power associativity and diassociativity to mention a few, will have cycles (even long ones). These identities are found to be cryptographic in nature for universal Osborn loops and thereby called cryptographic identities. They were also found applicable to security patterns, arrangements and networks which the CIP may not be applicable to.
Coronal Loops: Observations and Modeling of Confined Plasma
Fabio Reale
Living Reviews in Solar Physics , 2010,
Abstract: Coronal loops are the building blocks of the X-ray bright solar corona. They owe their brightness to the dense confined plasma, and this review focuses on loops mostly as structures confining plasma. After a brief historical overview, the review is divided into two separate but not independent parts: the first illustrates the observational framework, the second reviews the theoretical knowledge. Quiescent loops and their confined plasma are considered, and therefore topics such as loop oscillations and flaring loops (except for non-solar ones which provide information on stellar loops) are not specifically addressed here. The observational section discusses loop classification and populations, and then describes the morphology of coronal loops, its relationship with the magnetic field, and the concept of loops as multi-stranded structures. The following part of this section is devoted to the characteristics of the loop plasma and of its thermal structure in particular, according to the classification into hot, warm, and cool loops. Then, temporal analyses of loops and the observations of plasma dynamics and flows are illustrated. In the modeling section some basics of loop physics are provided, supplying some fundamental scaling laws and timescales, a useful tool for consultation. The concept of loop modeling is introduced and models are distinguished between those treating loops as monolithic and static, and those resolving loops into thin and dynamic strands. Then, more specific discussions address modeling the loop fine structure and the plasma flowing along the loops. Special attention is devoted to the question of loop heating, with separate discussion of wave (AC) and impulsive (DC) heating. Finally, a brief discussion about stellar X-ray emitting structures related to coronal loops is included and followed by conclusions and open questions.
Bernoulli Loops in Smoke Rings  [PDF]
Kern E. Kenyon
Natural Science (NS) , 2019, DOI: 10.4236/ns.2019.1110030
Abstract: Bernoulli’s law is applied to the closed streamlines of a smoke ring, and the centrifugal force of the curved flow is balanced by a pressure gradient. Two equations in two unknowns, pressure and velocity, are combined into one equation in one unknown, velocity. Solving the governing equation algebraically produces a radial shear in the velocity such that the speed decreases outward inversely as the radius increases, which is the main result. Measurements are needed to verify the predicted structure of the velocity field.
The Topological Conditions: The Properties of the Pair of Conjugate Tress  [PDF]
Luis Hernandez-Martinez, Arturo Sarmiento-Reyes, Miguel A. Gutierrez de Anda
Journal of Software Engineering and Applications (JSEA) , 2010, DOI: 10.4236/jsea.2010.36059
Abstract: This paper presents some important properties emanating from the pair of conjugate trees. The properties are obtained by resorting to the fundamental loops and cutsets in the circuit topology. The existence of such a pair is one of the conditions for a nonlinear resistive circuit to have one and only one DC solution.
Modelling the Creative Process and Cycles of Feedback  [PDF]
Carol R. Aldous
Creative Education (CE) , 2017, DOI: 10.4236/ce.2017.812127
Abstract: Dual physicist and psychologist Shaw (1989) published an account speculating on the modelling of a series of feedback loops within the structure of the creative process following a series of in-depth interviews with 12 scientists concerning the use of cognitive and affective processes in the act of scientific creation. These feedback loops were hypothesized to operate between each phase of the classical model of creative problem solving as typified by the seminal work of Wallas (1926). However, data providing evidence of their operation has been scarce. Using a sizable sample (n = 405) and recently developed software that enables bidirectional pathways to be modelled (M-Plus v6), this study examines the evidence for the existence of feedback loops within the creative process using structural equation modelling (SEM) procedures. The research builds on the findings of a previous study in which participants solved two novel mathematics problems in the Mathematics Challenge for Young Australians. Empirical evidence for both the classical stage model of creative problem solving and Shaw’s feedback loops namely the Vinacke and Lalas loops, are presented and discussed. The participants were middle school students in Grades 7 to 10 drawn from across two states of Australia.
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