Journal articles: 'Ovaling'

1

Pecknold, David A., and Shahzad Rahman. "Ovaling of Ring‐Stiffened Cylindrical Shells." Journal of Engineering Mechanics 116, no. 12 (December 1990): 2681–701. http://dx.doi.org/10.1061/(asce)0733-9399(1990)116:12(2681).

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Akhlaghi, Tohid, and Ali Nikkar. "Effect of Vertically Propagating Shear Waves on Seismic Behavior of Circular Tunnels." Scientific World Journal 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/806092.

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Seismic design loads for tunnels are characterized in terms of the deformations imposed on the structure by surrounding ground. The free-field ground deformations due to a seismic event are estimated, and the tunnel is designed to accommodate these deformations. Vertically propagating shear waves are the predominant form of earthquake loading that causes the ovaling deformations of circular tunnels to develop, resulting in a distortion of the cross sectional shape of the tunnel lining. In this paper, seismic behavior of circular tunnels has been investigated due to propagation of shear waves in the vertical direction using quasi-static analytical approaches as well as numerical methods. Analytical approaches are based on the closed-form solutions which compute the forces in the lining due to equivalent static ovaling deformations, while the numerical method carries out dynamic, nonlinear soil-structure interaction analysis. Based on comparisons made, the accuracy and reliability of the analytical solutions are evaluated and discussed. The results show that the axial forces determined using the analytical approaches are in acceptable agreement with numerical analysis results, while the computed bending moments are less comparable and show significant discrepancies. The differences between the analytical approaches are also investigated and addressed.

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Mgbokwere, C., and M. Callabresi. "Numerical Simulation of a Heat-Treated Ring Gear Blank." Journal of Engineering Materials and Technology 122, no. 3 (March 2, 2000): 305–14. http://dx.doi.org/10.1115/1.482802.

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Carburization and quenching of steels in general has been and continues to be an important commercial manufacturing process for steel components. The minimization of distortion, cracking, and residual stresses are major issues that need to be properly understood in order to efficiently produce high quality components. To assist process engineers in understanding the effect process parameters have on these major issues, a numerical study was conducted on an automotive transmission ring gear. The ring gear has substantial ovaling distortion, which cannot always be straightened within the design tolerances of the part thereby leading to a 3–5 percent rejection rate. The purpose of this report is to predict the distortions, microstructural phase changes, residual stresses, and hardness that occur during quenching using finite element techniques. The ABAQUS model from the NCMS Heat Treatment Prediction Program was used to perform the simulations. This report describes a two-dimensional simulation of the gear blank with the wall thinned where the teeth would have been located to represent the proper thermal mass. The gear blank geometry is essentially the same as the gear geometry without the teeth; moreover it has the same dimensions exhibited by the gear. Even though the ovaling caused by distortion is a three-dimensional problem the two-dimensional representation was chosen as an initial step before simulating the more complex three-dimensional gear geometry. The symmetry of the blank can be exploited by allowing fewer elements to be used for the finite element analysis which in turn will decrease the simulation times of the problem. [S0094-4289(00)01103-8]

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Pandey, Suresh K., Liliana Werner, Edward M. Wilson, Andrea M. Izak, and David J. Apple. "Capsulorhexis ovaling and capsular bag stretch after rigid and foldable intraocular lens implantation." Journal of Cataract & Refractive Surgery 30, no. 10 (October 2004): 2183–91. http://dx.doi.org/10.1016/j.jcrs.2004.02.079.

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5

Lu, Qingrui, Shijun Chen, Yi Chang, and Chunfeng He. "Comparison between Numerical and Analytical Analysis of the Dynamic Behavior of Circular Tunnels." Earth Sciences Research Journal 22, no. 2 (April 1, 2018): 119–28. http://dx.doi.org/10.15446/esrj.v22n2.72248.

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Dynamic behavior of underground structures is controlled by the strain field imposed by wave propagation and by the interaction between rock mass and structures. Shear and pressure waves propagating in the plane of the cross-section of the tunnel generate ground distortions, which tend to cause ovaling deformations of the lining. In this paper, the seismic response of a circular tunnel subjected respectively to shear waves and pressure waves will be analyzed both analytically and numerically at first, and then a complete 3D analysis will be given to show the overall effects on a tunnel induced by seismic events considering seismic inputs in three directions.

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6

Lu, Qing Rui, Hai Ying Jiang, Perino Andrea, and Dan Xie. "Static and Dynamic Analysis for Ovaling Deformation of Circular Tunnels under No-Slip Conditions." Applied Mechanics and Materials 353-356 (August 2013): 1609–13. http://dx.doi.org/10.4028/www.scientific.net/amm.353-356.1609.

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Many underground structures have witnessed great damage in recent earthquakes. Thus underground structures in earthquake prone zones should be designed to withstand both static overburden loads and earthquake loads. In this paper, different closed form solutions for the analysis of the tunnel response, are considered as developed on the basis of the theory that the stress increment due to seismic loading can be assessed through a correct estimate of free-field deformation, while the internal forces of tunnel linings subjected to overburden loads can also be estimated through an assumption of far-field stress using the developed solutions. Numerical studies have been performed to validate the available analytical solutions.

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7

Fanous, F., and L. Greimann. "Behavior of a Nuclear Steel Containment Equipment Hatch at Large Strain." Journal of Pressure Vessel Technology 110, no. 2 (May 1, 1988): 199–204. http://dx.doi.org/10.1115/1.3265587.

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During a severe accident, buckling of a steel containment hatch door, large deformation and ovaling of the hatch sleeve are potential causes of mismatch at the sealing surface which can result in a leakage path. A three-dimensional nonlinear finite element analysis of a typical steel containment/sleeve/hatch assembly that includes containment stiffeners, pretensioned swing bolts, and hatch door geometric imperfection is presented. The analysis was carried out to the nonlinear range up to large strains. The results indicated that the buckling load occurs at pressure, far above that which causes gross yielding of the shell plate. Although buckling of the hatch door increased the relative motions of the hatch sleeve and the hatch door, the motions remained sufficiently small to prevent leakage.

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Zamani, Reza, and M. R. Motahari. "The effect of soil stiffness variations on Tunnel Lining Internal Forces under seismic loading and Case comparison with existing analytical methods." Ciência e Natura 37 (December 21, 2015): 476. http://dx.doi.org/10.5902/2179460x20879.

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Closed-form solutions are of great interest for quick and accurate evaluation of stresses and displacements around underground excavations. Dynamic effects on underground structures have often been neglected based on the assumption that their response to earthquake loading is relatively safe as compared to that of surface structures. Nevertheless, several examples of recorded damage to underground structures for which seismic forces were not considered in the original design. Therefore, during the seismic excitement, tunnels are basically subjected to three kinds of deformation : axial compression and extension, longitudinal bending and ovaling or racking. In the present investigation a series of numerical analyses under the influence of soil hardness parameters based on no-slip between soil and tunnel lining were performed, using finite element code PLAXIS, and outputs were compared with result of analytical solutions.

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9

Park, Kyung-Ho, Kullachai Tantayopin, Bituporn Tontavanich, and Adisorn Owatsiriwong. "Analytical solution for seismic-induced ovaling of circular tunnel lining under no-slip interface conditions: A revisit." Tunnelling and Underground Space Technology 24, no. 2 (March 2009): 231–35. http://dx.doi.org/10.1016/j.tust.2008.07.001.

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10

Hashash, Youssef M. A., Duhee Park, and John I. Chiang Yao. "Ovaling deformations of circular tunnels under seismic loading, an update on seismic design and analysis of underground structures." Tunnelling and Underground Space Technology 20, no. 5 (September 2005): 435–41. http://dx.doi.org/10.1016/j.tust.2005.02.004.

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11

Ng, Jacqueline, Soroosh Behshad, and Marjan Farid. "Review of Surgical Techniques for Posterior Chamber Intraocular Lens Fixation in the Absence of Capsular Lens Support." US Ophthalmic Review 08, no. 02 (2015): 86. http://dx.doi.org/10.17925/usor.2015.08.02.86.

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This is a review of surgical options for posterior chamber intraocular lens (IOL) fixation in the absence of adequate capsular support. The indications, techniques, and outcomes for posterior chamber iris-sutured and scleral-fixated IOLs, including trans-scleral sutured and trans-scleral tunnel glued fixation, are reviewed. Iris-sutured IOL fixation may be appropriate in cases in which small corneal incisions with a foldable IOL are desired, but are only possible in cases of adequate iris tissue, and may be complicated by pupil ovaling and iris trauma, which can lead to prolonged inflammation in some studies. Scleral-sutured IOL fixation does not require robust iris tissue and decreases the risk for iris trauma, but is technically more demanding, may require larger incisions, and poses potentially more posterior segment complications. There are also ongoing concerns for suture exposure, erosion, and late suture breakage and IOL dislocation. Scleral tunnel-glued IOL fixation is a more recent innovation that avoids sutures and concerns for suture-related complications, and can be completed through smaller incisions with a foldable IOL. However, long-term studies are pending.

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12

ITO, Tomohiro, Hideyuki MORITA, Akihisa SUGIYAMA, Yoji KAWAMOTO, Eiji SHIRAI, and Hideyasu OGO. "233 Study on the Ovaling Vibration Phenomena Observed at the Upper Side Wall of a Thin Cylindrical Liquid Tank." Proceedings of the Dynamics & Design Conference 2003 (2003): _233–1_—_233–5_. http://dx.doi.org/10.1299/jsmedmc.2003._233-1_.

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13

Thandavamoorthy, T. S. "Investigations on Internally Ring-Stiffened Joints of Offshore Platforms." Journal of Offshore Mechanics and Arctic Engineering 122, no. 4 (May 22, 2000): 233–42. http://dx.doi.org/10.1115/1.1290401.

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The paper presents in detail the experimental and numerical investigations on tubular joints that are stiffened internally with three annular rings in order to study their behaviors and evaluate their strengths under axial brace compression loading. The nominal chord and brace diameters of the tested T and Y-joints were 324 and 219 mm and their thicknesses were 12 and 8 mm, respectively. The tested joints are approximately quarter-size when compared to the largest joints in the platforms built in a shallow water depth of 80 m in the Bombay High field. Some of the joints were actually fabricated by a leading offshore agency that is directly involved in the fabrication of prototype structures. Bending of the chord as a whole was observed to be the predominant mode of deformation of the internally ring-stiffened joints in contrast to ovaling and punching shear of the unstiffened joints. Strengths of the internally ring-stiffened joints were found to be almost twice that of unstiffened joints of the same dimensions. A tri-linear stress-strain model that takes into account the strain-hardening characteristics of the material was developed to assess the strength of the internally ring-stiffened joints. Finite element analysis (FEA) was performed to predict the bending deflection of the internally ring-stiffened joints under axial brace compression loading. This FEA used NISA II software package and was based on the tri-linear model proposed in this study. [S0892-7219(00)00104-7]

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14

ITO, Tomohiro, Hideyuki MORITA, Koji HAMADA, Akihisa SUGIYAMA, Yoji KAWAMOTO, Eiji SHIRAI, and Hideyasu OGO. "Study on Dynamic Buckling Behavior of a Cylindrical Liquid Storage Tanks under Seismic Excitation (2nd Report, Phenomena on Nonlinear Ovaling Vibration at the Upper Wall)." Transactions of the Japan Society of Mechanical Engineers Series C 70, no. 695 (2004): 1897–905. http://dx.doi.org/10.1299/kikaic.70.1897.

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15

Peng, Deping, Zhongwang Gong, Shumin Zhang, and Gaochao Yu. "Two-Roller Continuous Calibration Process by Compression for Submarine Pipelines." Symmetry 13, no. 7 (July 7, 2021): 1224. http://dx.doi.org/10.3390/sym13071224.

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Submarine pipeline is a key part in the development of deep sea and ultra-deep sea oil and gas. In order to reduce the ovality of pipes and improve their compressive strength, a two-roller continuous calibration (TRCC) process by compression is proposed. A springback analysis of compress bending is carried out, and an analytical model is established, which predicts ovality after calibration and provides a theoretical basis for roller shape design and process parameter formulation. Numerical simulation and physical experiments are carried out. The distribution of stress and strain is analyzed. The effects of initial ovality, reduction ratio and initial placement angle on the ovality after calibration are studied. When the reduction ratio is about 1%, the ovality is optimal. The theoretical analysis shows that the ovality after calibration is about 0.03%, and the ovality after calibration by numerical simulation and experiment is less than 0.45%, proving the feasibility of the process.

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16

Yong, Kang, and Wei Chen. "Mathematical Model Establishment and Analysis on the Pipe Deformation under External Pressure with the Ovality." Advanced Materials Research 760-762 (September 2013): 2263–66. http://dx.doi.org/10.4028/www.scientific.net/amr.760-762.2263.

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Beside the residual stresses and axial loads, other factors of pipe like ovality, moment could also bring a significant influence on pipe deformation under external pressure. The Standard of API-5C3 has discussed the influences of deformation caused by yield strength of pipe, pipe diameter and pipe thickness, but the factor of ovality degree is not included. Experiments and numerical simulations show that with the increasing of pipe ovality degree, the anti-deformation capability under external pressure will become lower, and ovality affecting the stability of pipe shape under external pressure is significant. So it could be a path to find out the mechanics relationship between ovality and pipe deformation under external pressure by the methods of numerical simulations and theoretical analysis.

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17

Li, Yi Bo, Ming Hui Huang, and Xin Jiang Lu. "Improvement in Ovality of Pipeline Steel X80 with Weld Power under Multi-Wire SAW Welding Process." Advanced Materials Research 239-242 (May 2011): 1823–31. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.1823.

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Pipeline steel X80 is a kind of advanced high grade steel and commonly used in long-distance transportation of oil and gas. Ovality of the pipe plays key role in improving its crushing strength. In this paper, a simulation method is proposed to improve the performance of ovality of X80 Pipeline Steel. First, a 3D thermo-mechanical coupled finite element model of the multi-wire SAW welding processes is built using MSC.MARC, upon which parameters of double ellipsoid heat source model is determined. Then, the relationship between weld power and ovality is studied under difference process inputs and a satisfactory weld power is found to decrease the ovality of the pipeline steel. Finally, validation and prediction of deformation and ovality of the pipeline is carried out via plate welding experiments.

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18

Safdarian, R. "Experimental and numerical investigation of wrinkling and tube ovality in the rotary draw bending process." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 16 (May 19, 2019): 5568–84. http://dx.doi.org/10.1177/0954406219850857.

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The tube wrinkling, ovality, and fracture are the main defects in the rotary draw bending process, which happen by incorrect selection of process parameters. In the present study, the wrinkling, fracture, and ovality of BS 3059 steel tube in the rotary draw bending were investigated using the experimental tests and the finite element method. The numerical results were verified using the experimental tests for tube ovality prediction. The tube fracture was predicted using the Gurson–Tvergaard–Needleman damage model in the rotary draw bending numerical simulations. The design of experiment based on the response surface method and the finite element method was used to investigate the effects of rotary draw bending parameters such as boosting velocity of pressure die, mandrel position, number of balls, and pressure of pressure die on the wrinkling, fracture, and tube ovality. The experimental and numerical results indicated that the mandrel position was one of the main parameters, which influence the tube ovality. The tube ovality and wrinkling increased with the increase in the mandrel position.

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19

Zhou, Zhao Ming, Fu Wan, Lei Wang, Zhang Hua Lian, and Yong Chen. "EMAT for Coiled-Tubing Wall Thickness and Ovality Measuring." Applied Mechanics and Materials 105-107 (September 2011): 1903–7. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1903.

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This paper presents a new wall thickness and ovality measuring method engineered for reliable field use. This paper describes the electromagnetic ultrasonic technique in coiled tubing detection. This paper describes requirements for Coiled Tubing specifications, which measuring different parameters, some of which include diameter, ovality, and wall thickness. This method not only thickness measurements but also ovality measuring will be made. This article discusses the electromagnetic ultrasonic thickness measurement of the system components, and experimental tests have shown. Ovality measurement sensor layout is designed. This paper discusses the development of this new methods, this system is suitable for non-contact, real-time, on-line high-speed data measurements.

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20

Pervez, Tasneem, and Sayyad Zahid Qamar. "Finite Element Analysis of Tubular Ovality in Oil Well." Advanced Materials Research 264-265 (June 2011): 1654–59. http://dx.doi.org/10.4028/www.scientific.net/amr.264-265.1654.

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This paper presents the finite element analysis of tubular expansion in oval bore holes such as those frequently observed in Upper Natih reservoirs. The minimum inner diameter of the expanded tubular must be larger than the drift diameter set by American Petroleum Institute (API) standards. If the minimum inner diameter is smaller than drift diameter, completion equipments can not be run successfully, which is necessary to complete an oil-well for production. The phenomenon of tubular ovality has been previously unknown to petroleum industry. Finite element model of tubular expansion in oval bore-holes is developed to determine the tubular ovality and compared with measured ovality. It was found that ovality increases linearly with tubular expansion ratio. With increase in expansion ratio, the tubular contact length with formation and developed contact pressure increases. Tubular ovality, if not considered in well design, may lead to premature tubular failure due to lower collapse rating and higher stresses.

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21

Oliver i Martínez-Fornés, Xavier, Pere Casals Tortras, Esther Fanlo Grasa, and Jordi García Pausas. "Pluchea ovalis (Pers.) DC., nueva cita en el Valle del Sous (Marruecos)." Acta Botanica Malacitana 32 (December 1, 2007): 301–4. http://dx.doi.org/10.24310/abm.v32i0.7115.

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Pluchea ovalis (Pers.) DC., new record in the Sous Valley (Morocco) Palabras clave. Pluchea ovalis, Asteraceae, especie tropical, especie amenazada.Key words. Pluchea ovalis, Asteraceae, tropical species, threatened species.

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22

Tsuge, Masashi, Mohammed Bahou, Yu-Jong Wu, Louis Allamandola, and Yuan-Pern Lee. "Infrared spectra of ovalene (C32H14) and hydrogenated ovalene (C32H15˙) in solid para-hydrogen." Physical Chemistry Chemical Physics 18, no. 41 (2016): 28864–71. http://dx.doi.org/10.1039/c6cp05701b.

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23

Anderson, Eur Ing A., and G. R. Johnson. "Effect of Tube Ovalling on Pressure Wave Propagation Speed." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 204, no. 4 (December 1990): 245–51. http://dx.doi.org/10.1243/pime_proc_1990_204_263_02.

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24

Srinivasulu, M., M. Komaraiah, and C. S. Krishna Prasada Rao. "Application of Response Surface Methodology to Predict Ovality of AA6082 Flow Formed Tubes." International Journal of Manufacturing, Materials, and Mechanical Engineering 3, no. 1 (January 2013): 52–65. http://dx.doi.org/10.4018/ijmmme.2013010104.

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Flow-forming is eco-friendly, chipless manufacturing process employed in the manufacture of thin walled seamless tubes. Ovality, the out of roundness is one of basic form of errors encountered in the tubular components. In the present research, a response surface model has been developed to predict ovality of AA6082 alloy pre-forms using Design of Experiments. The experiments are performed on a flow forming machine with a single roller. The process parameters selected for the present investigation are axial feed of the roller, the speed of the mandrel, and roller radius. Box-Behnken Design, a standard response surface methodology has been used to conduct the experimental runs. The developed response surface model successfully predicts the ovality of AA6082 flow formed tube within the range of selected process parameters. It has been found that, roller feed is the most important process parameter influencing the ovality of AA6082 flow formed tube.

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25

Zarrabi, K., and A. Basu. "An Artificial Neural Network Approach to Plastic Collapse of Oval Boiler Tubes." Advanced Materials Research 41-42 (April 2008): 421–26. http://dx.doi.org/10.4028/www.scientific.net/amr.41-42.421.

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Boilers in power, refinery and chemical processing plants contain extensive range of tube bends. Tube bends are manufactured by bending a straight-section tube. As a result, the crosssection of a tube bend becomes oval. Using the finite element analysis (FEA) and artificial neural network (ANN), the paper presents the relationships between the plastic collapse pressures and tube bend dimensions with various degrees of ovality. It is found that as ovality increases the plastic collapse pressure decreases. Also, the reduction of plastic collapse pressure with ovality is small for a thick tube bend when compared with that for a thin tube bend.

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26

Lai, Yi Nan, G. Y. Zhang, H. N. Yu, and Gang Feng Liu. "Numerical Simulation and Optimal Design of Rotary Draw Bending Pipe." Applied Mechanics and Materials 10-12 (December 2007): 172–76. http://dx.doi.org/10.4028/www.scientific.net/amm.10-12.172.

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The numerical simulation method is used to solve the problems of pipe bending manufacturing such as die with fine cracks, ovality of pipe. The fan-shaped die is welded with steel plate in circle and rib in radial direction by the analysis of structural deformation. The optimal design is provided with ovality of pipe as object variable and sliding slot dimensions as design variables. Compared with experiential shape groove of slot, ovality of optimized slot decreases about 10.5% in average. It greatly reduced the production cost using computer simulation method to replace a lot of experiment improving tube-bending production.

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Sandhu, Kamaldeep, Rajesh Jain, Inderjeet Kaur, and Bhushan Kumar. "Role ofPityrosporum ovalein Guttate Psoriasis." Journal of Dermatology 30, no. 3 (March 2003): 252–54. http://dx.doi.org/10.1111/j.1346-8138.2003.tb00383.x.

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28

Bujang, Japar Sidik, Lim Lai Huat, Muta Harah Zakaria, Azis Arshad, and Hisao Ogawa. "LABORATORY CULTURE OF THE SEAGRASS, Halophila ovalis (R.BR.) HOOKER F." Marine Research in Indonesia 33, no. 1 (June 30, 2008): 1–6. http://dx.doi.org/10.14203/mri.v33i1.500.

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A small-culture system for growing of Halophila ovalis was developed. Plugs of explants were successfuly grown in the native substrate and under the light regime of ~200 imol m-2 s-1. The culturing of H. ovalis in the laboratory permitted observations on (i) the sustain growth and the development of the population, (ii) the reproductive biology (flowering and fruiting) and (iii) the pattern of seedling development from seeds to mature plants. Plants increased in density via vegetative propagation and sexual reproduction. Plants produced male, female flowers and fruits. The presence of viable seeds and seedlings demonstrated the successful pollination and sexual reproduction of H. ovalis in culture. The morphology of progressive development of H. ovalis seedlings to juvenile or young plants for H. ovalis in culture is described.

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Ramaswami, P., P. Senthil Velmurugan, and R. Rajasekar. "Effect of Ovality in Inlet Pigtail Pipe Bends Under Combined Internal Pressure and In-Plane Bending for Ni-Fe-Cr B407 Material." Archives of Metallurgy and Materials 62, no. 3 (September 26, 2017): 1881–87. http://dx.doi.org/10.1515/amm-2017-0285.

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Abstract The present paper makes an attempt to depict the effect of ovality in the inlet pigtail pipe bend of a reformer under combined internal pressure and in-plane bending. Finite element analysis (FEA) and experiments have been used. An incoloy Ni-Fe-Cr B407 alloy material was considered for study and assumed to be elastic-perfectly plastic in behavior. The design of pipe bend is based on ASME B31.3 standard and during manufacturing process, it is challenging to avoid thickening on the inner radius and thinning on the outer radius of pipe bend. This geometrical shape imperfection is known as ovality and its effect needs investigation which is considered for the study. The finite element analysis (ANSYS-workbench) results showed that ovality affects the load carrying capacity of the pipe bend and it was varying with bend factor (h). By data fitting of finite element results, an empirical formula for the limit load of inlet pigtail pipe bend with ovality has been proposed, which is validated by experiments.

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Pensak, Myles L. "Fenestra nov-ovalis revisited." Current Opinion in Otolaryngology & Head and Neck Surgery 11, no. 5 (October 2003): 315. http://dx.doi.org/10.1097/00020840-200310000-00001.

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31

Katsura, S. "Wind-excited ovalling vibration of a thin circular cylindrical shell." Journal of Sound and Vibration 100, no. 4 (June 1985): 527–50. http://dx.doi.org/10.1016/s0022-460x(85)80005-5.

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32

Uematsu, Yasushi, Noboru Tsujiguchi, and Motohiko Yamada. "Mechanism of ovalling vibrations of cylindrical shells in cross flow." Wind and Structures 4, no. 2 (April 25, 2001): 85–100. http://dx.doi.org/10.12989/was.2001.4.2.085.

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33

Hillewaere, Jeroen, Joris Degroote, Geert Lombaert, Jan Vierendeels, and Geert Degrande. "Wind-structure interaction simulations of ovalling vibrations in silo groups." Journal of Fluids and Structures 59 (November 2015): 328–50. http://dx.doi.org/10.1016/j.jfluidstructs.2015.09.013.

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Putra, Rafiansyah, and Mahfudz Al Huda. "OPTIMASI DESAIN PARAMETER UNTUK MENGHILANGKAN CACAT OVALITY PADA PROSES PEMESINAN PEMBUATAN PRODUK WELLHEAD." Jurnal ASIIMETRIK: Jurnal Ilmiah Rekayasa & Inovasi 2, no. 2 (July 8, 2020): 115–24. http://dx.doi.org/10.35814/asiimetrik.v2i2.1372.

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Produk Wellhead digunakan sebagai penutup kepala sumur setelah pengeboran minyak selesai dilakukan. Produk ini dibuat dengan proses turning dan milling. Permasalahan yang dihadapi adalah masih ditemukan cacat dimensi ovality proses pemesinan. Penelitian ini dilakukan untuk menentukan setting parameter optimum dari proses pemesinan turning dan milling dengan model persamaan regresi yang optimal. Parameter yang ditentukan adalah Kecepatan Potong (Vc), Kecepatan Pemakanan (f), dan Kedalaman Potong (Ap). Dengan metode experimental yang dilakukan dengan mengambil 20 sampel produk dengan setting parameter yang berbeda-beda. Hasil percobaan yang dilakukan, pada proses turning parameter yang paling berpengaruh terhadap ovality adalah kedalaman potong (Ap), dan pada proses milling adalah Kecepatan Potong (F). Selanjutnya dilakukan analisa dengan metode Surface Responseuntuk mendapatkan persamaan regresi optimal untuk ovality.

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35

Buckshumiyan, A., A. R. Veerappan, and Subramaniam Shanmugam. "Effect of Shape Imperfections on Thin-Walled Pipe Bends under Out-Of-Plane Moment and Internal Pressure." Applied Mechanics and Materials 592-594 (July 2014): 1050–54. http://dx.doi.org/10.4028/www.scientific.net/amm.592-594.1050.

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This paper quantifies the effect of ovality and thinning/thickening of thin-wall pipe bend modeled using the geometric parameters of r/t=15 and 20 and λ=0.1 to 0.3. For each model the ovality and thinning is varied from 5% to 20 % in steps of 5 % .The collapse loads were obtained from twice-elastic-slope method of pipe bends subjected to out-of-plane moment with and without internal pressure. Large displacement analysis was performed on elastic-perfectly plastic material using the nonlinear FE package of ABAQUS. The analyzed shows that the thinning effect is insignificant and ovality produce the significant effect of upto 27.7% decrease in collapse load for pipe bend subjected to combined moment and internal pressure.

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Amale, Delya, Khristin I. F. Kondoy, and Ari B. Rondonuwu. "Morphometric Structure of Seagrass Halophila ovalis in Tongkeina, Bunaken Subdistrict, Manado City and Mokupa, Tombariri Subdistrict, Minahasa District Coastal Waters." JURNAL ILMIAH PLATAX 4, no. 2 (November 1, 2016): 67. http://dx.doi.org/10.35800/jip.4.2.2016.14018.

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Seagrass is vascular plant with rhizome roots system, trunk system and leafs that can be differenciated. Genesal characteristic of this family, amoy others, the leaf tend to have two branches, (and absent of) ligula as been found an Potamogetonaceae family, linier form af leaf, round, oval, sessile, enlarge branch with paraleel vfinger like ciramferule connected wirb crossed lower duct or perpendicular. This study was conducted in two locations namely Tongkeina, Bunaken Subdistrict, Manado City and Mokupa, Tombariri Subdistrict, Minahasa District coastal waters. Until recently there is no study yet been done regarding the comparison on morphological size of H. ovalis based on different sample location (near mangroves, seagrass beds and coral reefs) and comparing the result of morphological measurement among the locations studied. Data collection was done by using exploratory survey method where samples are directly collected, washed with seawater and put it on plastic bag. The sampling site was determined by using GPS before collecting the sample of H. ovalis that consist of 20 individuals from each station. The samples that been washed and labeled were then put in the plastic bag with alcohol to avoid the damage on seagrass sample. The results show that H. ovalis from Mokupa village is smaller than from Tongkaina. This is possibly caused the pressure of villager in Mokupa usually having their main activity to catch fish along the coastal areas which is treatening also the life of seagrass. The discarded of both organic and non organic garbages remained from house holds and local tradiitional market also can hinder the growth of H. ovalis. Keyword : Morphometric, Halophila ovalis, Tongkaina, Mokupa Abstrak Lamun adalah tumbuhan vascular sejati, memiliki akar dengan sistem perakaran rhizoma, struktur batang dan daun yang dibedakan dengan jelas. Halophila ovalis termasuk dalam family Hydrocharitaceae. Ciri-ciri umum dari famili ini antara lain daun cenderung bercabang dua, daunnya tidak memiliki ligula seperti yang dimiliki oleh famili Potamogetonaceae, bentuk daun linier (lurus), membulat, oval, sessile atau bercabang membesar dengan jari-jari paralel yang dihubungkan dengan saluran silang menurun atau perpendikuler. Penelitian ini dilaksanakan di dua lokasi yaitu di Perairan Pantai Tongkaina Kecamatan Bunaken Kota Manado dan Pantai Desa Mokupa Kecamatan Tombariri Kabupaten Minahasa. Penelitian ini dilakukan karena belum ada data mengenai perbandingan morfometrik lamun Halophila ovalis di dua lokasi ini. Tujuan penelitian yaitu membandingkan ukuran morfologi Halophila ovalis berdasarkan stasiun pengambilan sampel (daerah dekat mangrove, Lamun, dan Terumbu Karang) dan membandingkan ukuran morfologi Halophila ovalis berdasarkan lokasi pengambilan sampel. Pengambilan data dilakukan dengan menggunakan metode survei jelajah, sampel langsung dikumpulkan, dicuci dengan air laut dan dimasukkan ke dalam kantung plastik sampel. Saat pengambilan sampel dilakukan, posisi diplot dengan menggunakan GPS dan dilanjutkan dengan pengambilan sampel lamun Halophila ovalis sebanyak 20 individu setiap stasiun, kemudian sampel lamun di cuci dan di masukan dalam plastik yang sudah di berikan lebel, dan diisi alkohol agar sampel lamun tidak rusak. Pada hasil yang di peroleh terlihat bahwa Spesies Halophila ovalis di desa Mokupa lebih kecil dibandingkan Halophila ovalis di Tongkaina. Hal ini disebabkan aktivitas masyarakat desa Mokupa dilakukan dipinggir pantai dan juga aktivitas pembuangan sampah organik. Kata Kunci : Morfrometrik, Halophila ovalis, Tongkaina, Mokupa 1Mahasiswa Manajemen Sumberdaya Perairan FPIK UNSRAT 2Staf pengajar Fakultas Perikanan dan Ilmu Kelautan Universitas Sam Ratulangi

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Xue, Ji Jun, and Peng Wang. "Influence by Casing Geometric Imperfection on Anti-Collapse Strength with Finite Element Calculation." Applied Mechanics and Materials 268-270 (December 2012): 1114–18. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.1114.

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This essay was to build a finite element model to find the influence by oil casing geometric imperfection on anti-collapse strength. Two types of oil casing, Ф177.8×10.36mm/P110 andФ127×9.19mm/ P110, was taken for the calculation, considering the influence on anti-collapse strength by casing with two elements separately, ovality and non-uniformity of wall thickness. The calculation show that the anti-collapse strength of perfect casing perform better than that of imperfect casing. Ovality is an important factor for the anti-collapse strength, and the anti-collapse strength decrease rapidly as the ovality increase. Non-uniformity of wall thickness is the less important factor for anti-collapse strength, and the anti-collapse strength decrease slightly and slowly while the non-uniformity of wall thickness increase.

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Podder, Bikramjit, Prabas Banerjee, K. Ramesh Kumar, and Nirmal Baran Hui. "Development of ANFIS Model for Flow Forming of Solution Annealed H30 Aluminium Tubes." Solid State Phenomena 261 (August 2017): 378–85. http://dx.doi.org/10.4028/www.scientific.net/ssp.261.378.

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Modeling of the cold flow forming process for manufacturing of tube shaped solution annealed H30 Aluminum alloy has been considered in this present study. Three inputs (feed-speed ratio, roller in-feed and roller axial stagger) and three outputs viz. spring back, ovality and internal diameter have been considered for the present study.. Adaptive network-based fuzzy inference system (ANFIS) in Matlab platform has used for modeling purposes and its performance is compared with regression model. ANFIS has completely outperformed the regression models. Percentage accuracy in predicting all the three responses are found to be very high with ANFIS models. Prediction of ovality against the test data using regression analysis is found to be extremely erroneous. It indicates that additional process parameters are involved in predicting ovality which are not captured during the experimentation.

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Zhou, Zhao Ming, Fu Wan, De Sin Mao, Quan Chuan Xu, and Chen Xing Wei. "A New Approach to Coiled Tubing Improved Inspection." Applied Mechanics and Materials 105-107 (September 2011): 1957–60. http://dx.doi.org/10.4028/www.scientific.net/amm.105-107.1957.

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Many of the NDT methods used for casing, tubing, drill pipe and line pipe are applicable, with some minor modifications, to CT. This article describes the requirements of an ideal in-service inspection. This paper presents a new wall thickness and ovality measuring method engineered for reliable field use. This method based on flux gate testing technology discussed in this paper .This method not only will detect internal flaws and the density of micro-cracks, but also wall thickness measurements will be made. This paper discusses the development of this new method, the detection of eddy current testing program is used in coiled tubing ovality measurements. The key technology is the production of amorphous alloy core. Using this method measure diameter, wall thickness and ovality of CT, is currently being developed.

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Govindaraj, P., and Mouleeswaran Senthilkumar. "Performance Analysis of Thin Shell Bends under High Pressure and Temperature." Applied Mechanics and Materials 787 (August 2015): 296–300. http://dx.doi.org/10.4028/www.scientific.net/amm.787.296.

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Around 70% of the cost in piping industry is spent in the pipe manufacturing with optimum design of pipes without defects. Research on design of pipes has gained importance from the last decade. There are numerous methods being developed to improve the efficiency of piping units considering various parameters. The pipe tends to flatten when they are forced to bend, this geometrical changes has a significant role in the acceptability criteria of pipes. It is necessary to bend pipes in order to transmit liquid or gas from one place to other place. In this work special attention is given to pipe bends because of high stress concentration due to various loading conditions. From several kinds of piping systems, process piping systems are chosen for analysis since pipes used here transport important and hazardous materials. Damage to such piping system can cause serious loss to economy and human lives. The geometrical imperfection associated with bending of pipes is ovality. This degree of ovality determines the acceptance of pipes. Thickening and thinning effects cause additional problems like large plastic deformation and loss of flexibility respectively. Hence estimation of the best degree of ovality is required. In this work effect of ovality is estimated by taking the internal fluid pressure and In plane bending moment into account.

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Fazillah, Muhammad Rizki, Muhammad Agustiar, Rauzatul Sakinah, Nanda Muhammad Razi, Chitra Octavina, and Maria Ulfah. "Degradasi Ekosistem Lamun di Perairan Ahmad Rhang Manyang, Kabupaten Aceh Besar." Jurnal Laot Ilmu Kelautan 3, no. 1 (June 22, 2021): 35. http://dx.doi.org/10.35308/jlaot.v3i1.3471.

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Ekosistem lamun merupakan salah satu ekosistem yang penting dalam pengelolaan wilayah pesisir sehingga dibutuhkan kajian-kajian sebagai acuan pengelolaan. Penelitian ini bertujuan untuk memberikan informasi terbaru sebagai acuan informasi yang berguna dalam pengelolaan dan pengambilan kebijakan yang tepat terkait kelestarian ekosistem lamun di perairan Ahmad Rhang Manyang, Kabupaten Aceh Besar. Penelitian ini menggunakan metode simple random sampling. Hasil penelitian menunjukkan bahwa terdapat 2 jenis lamun yang ditemukan yaitu Halodule pinifolia dan Halophila ovalis. Penutupan lamun tertinggi yaitu dari jenis Halodule pinifolia dengan nilai 4,70 % sedangkan jenis Halophila ovalis yaitu 0,03 %. Nilai kerapatan tertinggi dari jenis Halodule pinifolia yaitu 66,14 ind/m2, sedangkan dari jenis Halophila ovalis sebesar 0,93 ind/m2. Indeks penutupan lamun dari masing-masing spesies termasuk dalam kategori miskin/rusak.Kata kunci : Ekosistem lamun, Halodule pinifolia, Halophila ovalis, Kerapatan lamun, Tutupan lamun.

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Li, Ruoxuan, Bai-Qiao Chen, and C. Guedes Soares. "Effect of Ovality Length on Collapse Strength of Imperfect Sandwich Pipes Due to Local Buckling." Journal of Marine Science and Engineering 10, no. 1 (December 24, 2021): 12. http://dx.doi.org/10.3390/jmse10010012.

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The effect of ovality length on imperfect sandwich pipes is investigated using the finite element method in the scenario of local buckling under external pressure. First, the finite element model of the imperfect sandwich pipelines is established in ANSYS and is validated by comparing the results from numerical simulation with those from experiments. Then, the effect of ovality features on the collapse strength of the sandwich pipes is studied. At last, based on the calculation results from 1200 cases, a prediction equation is proposed to represent the relationship between collapse strength and ovality length of imperfect sandwich pipes. Good agreement is achieved between the proposed equation and the calculation results, leading to the conclusion that the proposed simplified model can be an efficient tool in the evaluation of the local collapse strength of subsea sandwich pipes under external pressure.

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Lamit, Nadhirah, and Yasuaki Tanaka. "Effects of river water inflow on the growth, photosynthesis, and respiration of the tropical seagrass Halophila ovalis." Botanica Marina 64, no. 2 (March 31, 2021): 93–100. http://dx.doi.org/10.1515/bot-2020-0079.

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Abstract To investigate the effects of river waters on estuarine seagrass, the tropical seagrass Halophila ovalis was collected at Brunei Bay, Borneo, and was cultured under laboratory conditions for 18 days. Three treatments were set up in the experiment: natural seawater with a salinity 30 (S30), estuarine river water with a salinity 10 (S10), and the intermediate water that was composed of the seawater and river water with a salinity 20 (S20). New leaf production, the average length of new leaves, rhizome elongation, and photosynthetic rate of H. ovalis were significantly higher in S20 than S10. Chlorophyll a (chl a) and carotenoid content in H. ovalis were significantly lower in S10 than S20 and S30. Though the tropical river waters could potentially cause both positive and negative effects on seagrass, the present results suggested that low salinity would be the most influential factor to hinder the growth and metabolism of H. ovalis, and the salinity threshold was observed between 10 and 20. These results suggested that H. ovalis may be able to extend its present distribution to the upper estuary at this study site in the future.

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Ramadhan, Rizky, I. Gusti Ngurah Putra Dirgayusa, and Elok Faiqoh. "Skrining Fitokimia dan Uji Toksisitas Ekstrak Daun Lamun Halophila Ovalis di Perairan Pantai Karma dan Pantai Serangan, Bali." Journal of Marine and Aquatic Sciences 7, no. 2 (December 1, 2021): 140. http://dx.doi.org/10.24843/jmas.2021.v07.i02.p02.

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Seagrass produced active compounds in a form of secondary metabolites as a survival system from predator attack and extreme environmental conditions. The active ingredient of seagrass extract can be an anticancer and antifungal. This study aimed to determine the content of active compounds and differences of toxicity level in seagrass extracts especially Halophila Ovalis in waters of Karma Beach and Serangan Beach. The method used for cytotoxicity test was Brine Shrimp Lethality Test (BSLT) using Artemia salina as an experimental animal. The result of phytochemical test showed that the extract of Halophila Ovalis leaf in Karma Beach contained bioactive compounds, such as alkaloids and tannins. Another side, the extract of Halophila Ovalis leaf in Serangan Beach contained 3 types of bioactive compounds, those were alkaloids, tannins and triterpenoids. The toxicity tests by BSLT method showed that the extract of Halophila Ovalis leaf in both research sites was non-toxic. The result was LC50 where the LC50 value of Halophila Ovalis leaf extract at the lowest to highest concentrations ie, (10, 100, and 1000 ug / ml) did not give a 50% mortality effect on Arthemi salina eggs.

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Han, Zhan Guang, Ke Liu, and Jia Quan Zhang. "Ovality Defect Control for Round Casting Based on Mechanical Deformation Analysis." Advanced Materials Research 154-155 (October 2010): 151–57. http://dx.doi.org/10.4028/www.scientific.net/amr.154-155.151.

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Deformation of round castings due to thermal and/or mechanical strain may lead to the occurrence of their ovality defects during continuous casting. Presently, ovality defect from thermal deformation have been effectively controlled in actual casting process with the application of more advanced equipments and more sophisticated control strategies. But the control of ovality defect from larger mechanical deformation still cannot satisfy the need of caster design or higher qualified rate of castings. It is shown that excessive hot pressure while strand passes through tension leveler, is the main reason to generate larger mechanical deformation. With consideration of the characteristics of round caster and the requirement of safety production, a theoretical calculated model based on mechanical deformation analysis has been developed in the paper to eliminate ovality defect specially from the over large hot pressure. Calculation analysis suggests that groove design of drive roller and range of round section sizes should be the important consideration for the determination of hot pressure, and there always exists an optimum value for hot pressure when the machine equipments of round caster have been designed and installed. The model can provide a useful guideline for casting engineers to design the groove of drive roller and to determine reasonable safe hot pressure. Reliability of the model analysis has been verified by industrial application on a newly built round caster.

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Li, Shidong, Jeffrey D. Eisenman, and Darryl Mikulec. "Prediction of ovalling frequency for FRP chimney liners with circumferential stiffeners." Journal of Thermoplastic Composite Materials 25, no. 4 (September 9, 2011): 439–51. http://dx.doi.org/10.1177/0892705711411342.

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Uematsu, Y., K. Uchiyama, M. Yamada, and S. Sanjyo. "Ovalling oscillations of thin circular cylindrical shells in a cross flow." Journal of Fluids and Structures 2, no. 3 (May 1988): 285–307. http://dx.doi.org/10.1016/s0889-9746(88)80012-4.

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Hillewaere, J., J. Degroote, G. Lombaert, J. Vierendeels, and G. Degrande. "Computational aspects of simulating wind induced ovalling vibrations in silo groups." Journal of Computational and Applied Mathematics 246 (July 2013): 161–73. http://dx.doi.org/10.1016/j.cam.2012.06.033.

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Phandee, Surangkana, and Pimchanok Buapet. "Photosynthetic and antioxidant responses of the tropical intertidal seagrasses Halophila ovalis and Thalassia hemprichii to moderate and high irradiances." Botanica Marina 61, no. 3 (June 27, 2018): 247–56. http://dx.doi.org/10.1515/bot-2017-0084.

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Abstract This study investigated photosynthetic and oxidative stress-related responses to moderate (500 μmol photons m−2 s−1) and high irradiances (1500 μmol photons m−2 s−1) in two tropical intertidal seagrasses, Halophila ovalis and Thalassia hemprichii. Exposure to high irradiance for 3 h resulted in a large decline in the maximum quantum yield of photosystem II (Fv/Fm) and in the effective quantum yield of photosystem II (ΦPSII) but induced non-photochemical quenching (NPQ) and chloroplast clumping in H. ovalis. Thalassia hemprichii, however, showed only a minor decrease in Fv/Fm and ΦPSII, and no change in either NPQ or the intracellular arrangement of chloroplasts. The irradiance did not affect reactive oxygen species (ROS) or superoxide dismutase (SOD) activity in either seagrass, whereas high irradiance enhanced ascorbate peroxidase (APX) activity in H. ovalis. The results from a subsequent experiment using an oxidative stress inducer, methyl viologen (MV), also showed a higher degree of Fv/Fm inhibition in H. ovalis. These results show that H. ovalis is much more physiologically responsive to high irradiances and oxidative stress than T. hemprichii and that its photoprotective mechanisms involve NPQ, APX and reduction of the amount of light absorbed through the clumping of its chloroplasts.

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Sachdev, Kusum, and Dinesh K. Kulshreshtha. "Phenolic constituents of Coelogyne ovalis." Phytochemistry 25, no. 2 (January 1986): 499–502. http://dx.doi.org/10.1016/s0031-9422(00)85509-0.

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Journal articles on the topic 'Ovaling'

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