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Search Results: 1 - 10 of 1098 matches for " buckling curves "
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Experimental - theoretical study of axially compressed cold formed steel profiles
Be?evi? Miroslav,Kukaras Danijel
Facta Universitatis Series : Architecture and Civil Engineering , 2011, DOI: 10.2298/fuace1103367b
Abstract: Analysis of axially compressed steel members made of cold formed profiles presented in this paper was conducted through both experimental and numerical methods. Numerical analysis was conducted by means of "PAK" finite element software designed for nonlinear static and dynamic analysis of structures. Results of numerical analysis included ultimate bearing capacity with corresponding middle section force-deflection graphs and buckling curves. Extensive experimental investigation were also concentrated on determination of bearing capacity and buckling curves. Experiments were conducted on five series with six specimens each for slenderness values of 50, 70, 90, 110 and 120. Compressed simply supported members were analyzed on Amsler Spherical pin support with unique electronical equipment and software. Besides determination of forcedeflection curves, strains were measured in 18 or 12 cross sections along the height of the members. Analysis included comparisons with results obtained by different authors in this field recently published in international journals. Special attention was dedicated to experiments conducted on high strength and stainless steel members.
Characterization of non-connected Buchsbaum curves in P^n
Marta Casanellas
Le Matematiche , 1999,
Abstract: In this paper we characterize non-connected Buchsbaum curves C in P^n and we give a sharp bound for the number of disjoint connected components of C.
Analyzing Some Behavior of a Beam with Different Crack Positions Transversely inside It  [PDF]
Behrooz Yazdizadeh
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.51009
Abstract:

Vertical displacement, critical Euler buckling load and vibration behavior of a cracked beam are considered in this research. The crack inside the beam is placed in different positions and results compared for each crack position. On first Eigenvalue of free vibration results, there is a border that first Eigenvalue of free vibration does not change if center of crack is located on that border, and after that border, the first Eigenvalue of free vibration is increased that is a counterexample relation of critical Euler buckling load and first Eigenvalue of free vibration.

Potential Energy Curves & Material Properties  [PDF]
Devarakonda Annapurna Padmavathi
Materials Sciences and Applications (MSA) , 2011, DOI: 10.4236/msa.2011.22013
Abstract: Potential energy curves govern the properties of materials. A critical analysis of the potential energy curve helps better understand the properties of the material. Potential energy curve and in turn the properties of any material depend on the composition, bonding, crystal structure, their mechanical processing and microstructure. The type, strength, and directionality of atomic bonding controls the structure and material properties viz., melting temperature, thermal expansion, elastic stiffness, electrical properties, ductility and toughness etc. This paper attempts to bring out the correlation between the potential energy curves with the properties of materials.
Revisiting Galactic Rotation Curves Given a Noncommutative-Geometry Background  [PDF]
Peter K. F. Kuhfittig, Vance D. Gladney
Journal of Modern Physics (JMP) , 2014, DOI: 10.4236/jmp.2014.517187
Abstract: It was shown earlier by Rahaman et al. that a noncommutative-geometry background can account for galactic rotation curves without the need for dark matter. The smearing effect that characterizes noncommutative geometry is described by means of a Gaussian distribution intended to replace the Dirac delta function. The purpose of this paper is two-fold: 1) to account for the galactic rotation curves in a more transparent and intuitively more appealing way by replacing the Gaussian function by the simpler Lorentzian distribution proposed by Nozari and Mehdipour and 2) to show that the smearing effect is both a necessary and sufficient condition for meeting the stability criterion.
Body Mass Index, Waist Circumference and Cut-Off Points for Metabolic Syndrome in Urban Residents in Ningxia  [PDF]
Jianjun Yang, Hongyan Qiu, Hongyu Li, Yuhong Zhang, Xiujuan Tao, Yanna Fan
Open Journal of Endocrine and Metabolic Diseases (OJEMD) , 2015, DOI: 10.4236/ojemd.2015.512020
Abstract: A growing number of studies show that different countries and populations require different cut-off points for body mass index (BMI), and waist circumference (WC) leading to obesity. There are no data on optimal cut-off points to metabolic syndrome (MS) among urban residents in Ningxia. Our aim is to determine the appropriate cut-off points for BMI and WC associated with elevated prevalent MS risk among urban residents in Ningxia. A total of 2500 urban residents in Ningxia were examined from May 2008 to March 2009 in a community-based cross-sectional study. Height, body weight, waist circumference and hip circumference were measured to calculate BMI. Fasting blood glucose (FBG), plasma levels of triglyceride (TG), total cholesterol (TC), and high-density lipoprotein cholesterol (HDL-C) were examined using a blood glucose meter and the chromatographic enzyme method. BMI and WC were measured to assess overweight or obesity. Of these, 301 subjects were chosen according to metabolic syndrome diagnosis standards to form the case group. The control group comprised 301 healthy people without diabetes, hypertension, hyperlipemia, coronary heart disease, cerebrovascular disease, malignant tumors or chronic infections. Logistic regression and receiver-operating characteristic (ROC) curve analyses were used to determine optimal cut-off points for BMI and WC in relation to the area under the curve (AUC), sensitivity and specificity. The optimal cut-off points for male and female respectively were 24.78 kg/m2(sensitivity = 0.879, specificity = 0.648) and 24.72 kg/m2(sensitivity = 0.804, specificity = 0.767) for BMI, 85.95 cm (sensitivity = 0.701, specificity = 0.641) and 78.25 cm (sensitivity = 0.804, specificity = 0.528) for WC. Urban residents in Ningxia were at high risk of MS, and the cut-off points for BMI and WC were lower than the data currently recommended in Asian population.
Strength of Thin-Walled Lipped Channel Section Columns with Shell-Shaped Curved Grooves  [PDF]
Koki Hoshide, Mitao Ohga, Pang-jo Chun, Tsunemi Shigematsu, Sinichi Kawamura
Open Journal of Civil Engineering (OJCE) , 2018, DOI: 10.4236/ojce.2018.84036
Abstract: Thin-walled member is structurally superior to a construction member. However, by reason of complexity in structure the stress and the deformation to yield the cross section are complicated. Specially, in case thin-walled members, such as thin-walled channel section columns, which are subjected to compressive force, these members produce the local buckling, distortional buckling and overall buckling. A number of experimental and theoretical investigations subjected to axial compressive force are generated for thin-walled channel section columns with triangle-shaped folded groove by Hancock [1] and with complex edge stiffeners and web stiffeners by Wang [2]. In case thin-walled channel section column with folded groove which is subjected to axial compressive force, it is cleared that the buckling mode shapes are ordinarily generated for local buckling mode shape of plate-panel composing cross section of member in short member aspect ratio and overall buckling mode shape as column and distortional buckling mode shape interacting between local buckling and overall buckling similarly normal thin-walled member. It is cleared analytically and experimentally that buckling strength and critical strength of thin-walled channel section column with folded groove can increase sharply in comparison with that of normal thin-walled member composing only plate-panel. In this paper a new cross section of shell-shaped curved groove [3] was proposed instead of the thin-walled lipped channel section column with triangle- and rectangle-shaped folded grooves used ordinarily, and therefore the comparison and the examination of buckling strength and buckling behavior were generated in the case of preparing triangle-shaped folded and shell-shaped curved grooves to web and flange of thin-walled channel section column. And then in order to investigate the buckling behavior on the thin-walled channel section column with folded and curved grooves, exact buckling strength and the buckling mode shapes are generated by using the transfer matrix method. The analytical local distortional and overall elastic buckling loads of thin-walled channel section column with folded and curved grooves can be obtained simultaneously by use of the transfer matrix method. Furthermore, a technique to estimate the buckling mode shapes of these members is also shown.
Comment on “Equiprobability, Entropy, Gamma Distributions and Other Geometrical Questions in Multi-Agent Systems”, Entropy 2009, 11, 959-971
Raúl Toral
Entropy , 2009, DOI: 10.3390/e11041121
Abstract: The volume of the body enclosed by the n-dimensional Lamé curve defined by ? n i=1 x b i = E is computed.
Homogenization of Composite Plate Structures
Alena Zemanová
Bulletin of Applied Mechanics , 2009,
Abstract: The present contribution aims at the application of the computational homogenization methods to heterogeneous structural members subject to bending. The proposed approach is discussed with the emphasis given to the buckling behavior of perforated plates. The particular choice of this class of structures is motivated by the possibility to validate the derived homogenization procedures for thick and thin plates against the experimental data as well as the results of the detailed numerical modeling.
Potential Bacterial Health Risk Posed to Consumers of Fresh Coconut (Cocos nucifera L.) Water  [PDF]
Adolf K. Awua, Edna D. Doe, Rebecca Agyare
Food and Nutrition Sciences (FNS) , 2012, DOI: 10.4236/fns.2012.38149
Abstract: Coconut (Cocos nucifera L.) water is a refreshing drink consumed mostly directly from the fruit. However, in recent times, consumers in Accra prefer to have it transferred into plastic bags for later consumption; this favours a high risk of bacterial contamination. Since it is rich in nutrient, it may become unwholesome with possible high bacteria loads. However, its use for managing and preventing diarrhoeal diseases and the report that coconut water contains anti-bacterial proteins, suggests a bacteria growth inhibition potential for it. Therefore, the propensity of fresh coconut water to support the growth of two pathogenic bacteria was studied. Using mostly optical density measurement, and where possible, growth parameters and bacteria loads were estimated for the growth of two gram negative bacteria in fresh, stored and sterilized coconut water, and also in Luria-Bertani (LB) broth as a control. The study revealed that fresh coconut water is a drink favourable for the survival and growth of Escherichia coli, and Klebsiella pneumoniae. It supported the growth of these bacteria recording lag times of 101.4 ± 1.00 minutes for E. coli and 154.8 ± 0.45 minutes for K. pneumoniae, and high loads of viable cells of ~ 2.27 × 108 cfu/mL and > 2.83 × 108 cfu/mL at the stationary phase for E. coli and K. pneumoniae respectively. These and other growth parameters in coconut water were comparable to those in Luria-Bertani (LB) broth medium. However, when autoclaved, gamma irradiated or stored at 4℃ for two weeks or more, the growth of these bacteria becomes extremely limited. Fresh coconut water will support the growth of these bacteria to high and infective load of viable cell if it becomes contaminated with and is kept at ambient temperatures for two or more hours. Thus, it will be safer to consume coconut water directly from the fruit, since there is a high risk for bacteria contamination associated with the transfer and storage in other containers.
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