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Статті в журналах з теми "Tow Angle Placement"
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Bourgeois, Mark E., and Donald W. Radford. "Consolidation and Tow Spreading of Digitally Manufactured Continuous Fiber Reinforced Composites from Thermoplastic Commingled Tow Using a Five-Axis Extrusion System." Journal of Composites Science 5, no. 3 (March 5, 2021): 73. http://dx.doi.org/10.3390/jcs5030073.
Повний текст джерелаАнотація:
During the development of digitally manufactured, commingled tow continuous fiber reinforced composites, consolidation force was controlled using a controlled spring force that yielded a repeatable tow width. However, the use of the extruder face to consolidate the material requires that the extruder remain perpendicular to the placement surface throughout the process. When considering more complex tool contours including sloped surfaces, more than three axes of motion are necessary to maintain the perpendicularity of the extruder tip to the surface. In this effort, a five-axis system is developed and used to demonstrate the ability to consolidate over complex contours. In addition, the nozzle face temperatures required for good consolidation and wetout result in poor tow path fidelity when complex paths are introduced. The implementation of an automated, computer-controlled localized cooling system enables both good wetout and consolidation while also enabling more accurate changes in tow path due to improvements in local tow tack. With the development of the five-axis system it is also shown that the tow width can be adjusted by rotating the existing placement nozzle to angles not equal to 90°. Thus, through a combination of controlled localized cooling and real-time control of the nozzle angle, a possible approach to control of tow width, independent of the tow placement angle and radius of curvature during tow steering, is described.
2
Zhu, Yingdan, Shijie Qi, Hongli Jia, Pengcheng Shi, Youqiang Yao, Junfeng Hu, Philippe Boisse, and Haibing Xu. "Assessing tensile behavior of open-hole variable angle tow composites using a general gradient property simulation methodology." Journal of Reinforced Plastics and Composites 39, no. 19-20 (June 26, 2020): 742–57. http://dx.doi.org/10.1177/0731684420929094.
Повний текст джерелаАнотація:
Variable Angle Tow placement is a way to steer individual curvilinear fibers. This work presents the assessment of tensile behavior of open-hole composite laminates with Variable Angle Tow reinforcement. A new multi-scale finite element method, consisting of a microscale unit cell model and a macroscale gradient property model, is developed to simulate Variable Angle Tow structures with various fiber trajectories. The tensile strength and the failure process of open-hole reinforced laminates with Variable Angle Tow reinforcement under tensile loading are predicted and analyzed. Experiments are also conducted to investigate reinforcing efficiency and failure modes of the open-hole laminates. The comparison of predicted and experimental results for the tensile strength and failure modes of T700/Epoxy laminates demonstrates clearly that the mechanical behavior of Variable Angle Tow structure can be simulated very well by the proposed multi-scale model. Moreover, it is found that the tensile strength of Variable Angle Tow laminates is closely related to the eccentricity and it reaches the maximum value only when the trajectories of curvilinear fibers keeps consistent with maximum principal stress trajectories of the open-hole plate.
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Haavajõe, Anti, Madis Mikola, and Meelis Pohlak. "Design and Manufacturing of Variable Angle Tow Laminate." Key Engineering Materials 674 (January 2016): 59–64. http://dx.doi.org/10.4028/www.scientific.net/kem.674.59.
Повний текст джерелаАнотація:
Variable angle tow (VAT) laminates have shown enhanced stiffness/strength performance compared to conventional straight fiber laminates. Employment of VAT allows utilizing variable stiffness design of composite structure, thus it widens the design possibilities. As a result, composite structure with improved mechanical characteristics can be manufactured. The main aims of the current study are to give an overview on methods and algorithms used for analysis and design of VAT laminates, and to develop technology and equipment for manufacturing laminate with improved structural performance. In order to improve the accuracy of the compaction process, a set of experiments were carried out using a simple testing device. For measuring the compaction force, a pneumatic cylinder, pressure regulator and digital manometer were used. The temperature of the consolidation area and the heat distribution were screened with the thermal camera. Infrared heater was used as a heating source. Material used in the experiment was carbon fiber reinforced polyamide.Findings show that in addition to the main parameters – the compaction force and temperature, there are many minor factors, such as the compaction wheel diameter, material and surface roughness of the compaction roller, the material and surface roughness of the mold and the pretension in the laminating tape and also the laminating speed, all influence the quality of the final product.Key words: Advanced Fiber Placement Technology, Automated Fiber Placement, Automated Tape Laying, Fiber Reinforced Composites, Laminates
4
Yi, Minghui, Fei Liu, Wuxiang Zhang, and Xilun Ding. "Formation Mechanism and Modeling Method of Wrinkling Defects in Variable Angle Tow Steering Fiber Placement." Aerospace 9, no. 10 (October 19, 2022): 620. http://dx.doi.org/10.3390/aerospace9100620.
Повний текст джерелаАнотація:
Variable angle tow steering technology is capable of manufacturing complex aviation parts with a trajectory of intricate curvature planned based on stress or profile characteristics, which greatly improves the forming efficiency, design flexibility and mechanical properties of composite structures. In view of the forming defects such as buckling and wrinkles caused by the lateral bending of fiber prepreg tow, a theoretical buckling model based on the Rayleigh Ritz method, the principle of minimum potential energy and the viscoelastic foundation is established, in which the adhesion coefficient is characterized by the degree of intimate contact to introduce process parameters. On the basis of the contact mechanics analysis, the distribution of the compaction pressure and bending stress is studied to improve the theoretical model, and the critical buckling load and the minimum radius of the tow under the normal and tangential contact conditions are determined precisely. Finally, the finite element models of compaction and variable angle steering placement are proposed, and the theoretical model and simulation model are verified by corresponding trials. It is demonstrated that defects can be effectively suppressed through optimizing process parameters.
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Carvalho, João, Abdolrasoul Sohouli, and Afzal Suleman. "Fundamental Frequency Optimization of Variable Angle Tow Laminates with Embedded Gap Defects." Journal of Composites Science 6, no. 2 (February 20, 2022): 64. http://dx.doi.org/10.3390/jcs6020064.
Повний текст джерелаАнотація:
Variable stiffness composite laminates can improve the structural performance of composite structures by expanding the design space. This work explores the application of variable stiffness laminated composite structures to maximize the fundamental frequency by optimizing the tow angle. To this end, an optimization framework is developed to design the fiber angle for each layer based on the maximization of the fundamental frequency. It is assumed that the design process includes the manufacturing constraints encountered in the automated fiber placement process and a linear fiber angle variation. The current study improves existing results by considering embedded gap defects within the optimization framework. The plates are assumed symmetric, with clamped and simply supported boundary conditions. The optimal results and a comparison between the non-steered and steered plates with and without gaps are presented. Results show that, although gaps deteriorate the structural performance, fiber steering can still lead to an increase in the fundamental frequency depending on the plate’s geometry and boundary conditions.
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Bittrich, Lars, Axel Spickenheuer, José Humberto S. Almeida, Sascha Müller, Lothar Kroll, and Gert Heinrich. "Optimizing Variable-Axial Fiber-Reinforced Composite Laminates: The Direct Fiber Path Optimization Concept." Mathematical Problems in Engineering 2019 (February 19, 2019): 1–11. http://dx.doi.org/10.1155/2019/8260563.
Повний текст джерелаАнотація:
The concept of aligning reinforcing fibers in arbitrary directions offers a new perception of exploiting the anisotropic characteristic of the carbon fiber-reinforced polymer (CFRP) composites. Complementary to the design concept of multiaxial composites, a laminate reinforced with curvilinear fibers is called variable-axial (also known as variable stiffness and variable angle tow). The Tailored Fiber Placement (TFP) technology is well capable of manufacturing textile preforming with a variable-axial fiber design by using adapted embroidery machines. This work introduces a novel concept for simulation and optimization of curvilinear fiber-reinforced composites, where the novelty relies on the local optimization of both fiber angle and intrinsic thickness build-up concomitantly. This framework is called Direct Fiber Path Optimization (DFPO). Besides the description of DFPO, its capabilities are exemplified by optimizing a CFRP open-hole tensile specimen. Key results show a clear improvement compared to the current often used approach of applying principal stress trajectories for a variable-axial reinforcement pattern.
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Zhao, Wei, and Rakesh K. Kapania. "Buckling Analysis and Optimization of Stiffened Variable Angle Tow Laminates with a Cutout Considering Manufacturing Constraints." Journal of Composites Science 6, no. 3 (March 4, 2022): 80. http://dx.doi.org/10.3390/jcs6030080.
Повний текст джерелаАнотація:
Variable angle tow laminates (VAT) and stiffeners are known to redistribute the in-plane load distribution and tailor the buckling mode shapes, respectively, for improving structural performance. To leverage the benefits of using VAT laminates in the practical applications, in the present paper, we discuss buckling load maximization conducted for a stiffened VAT laminated plate with a central cutout considering VAT laminate manufacturing constraints. Three representative boundary conditions as seen in the aerospace structures are considered: in-plane axial displacement, in-plane pure shear, and in-plane pure bending displacements. Two common manufacturing constraints, the one on the automatic fiber placement (AFP) manufacturing head turning radius and the other on the tow gap/overlap, while fabricating VAT laminates are considered in the laminate design. These two manufacturing constraints are modeled by controlling the fiber path radius of curvature and tape parallelism in optimizing the fiber path orientations for the VAT laminates. Stiffener layout and fiber path angle for the VAT laminated plates are both considered in the buckling load maximization study. To avoid using a fine mesh in modeling the stiffened VAT laminates with a cutout when employing the finite element analysis during the optimization, the VAT laminated plate and the stiffeners are modeled independently. The displacement compatibility is enforced at the stiffener–plate interfaces to ensure that the stiffeners move with the plate. Particle swarm optimization is used as the optimization algorithm for the buckling load maximization study. Optimization results show that, without considering AFP manufacturing constraints, the VAT laminates can increase the buckling loads by 21.2% and 12.4%, respectively, comparing to the commonly used quasi-isotropic laminates and traditionally straight fiber path laminates for the structure under the in-plane axial displacement case, 19.7% and 12.5%, respectively, for the in-plane shear displacement case, and 62.1% and 26.6%, respectively, for the in-plane bending displacement case. The AFP manufacturing constraints are found to have different impacts on the buckling responses for the VAT laminates, which cause the maximum buckling load to be 9.3–10.1%, 3.0–3.2%, and 23.2–29.8% less than those obtained without considering AFP manufacturing constraints, respectively, for the present studied model under in-plane axial, shear, and bending displacements.
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Sánchez-Majano, Alberto Racionero, Rodolfo Azzara, Alfonso Pagani, and Erasmo Carrera. "Accurate Stress Analysis of Variable Angle Tow Shells by High-Order Equivalent-Single-Layer and Layer-Wise Finite Element Models." Materials 14, no. 21 (October 28, 2021): 6486. http://dx.doi.org/10.3390/ma14216486.
Повний текст джерелаАнотація:
New concepts of lightweight components are conceived nowadays thanks to the advances in the manufacture of composite structures. For instance, mature technologies such as Automatic Fibre Placement (AFP) are employed in the fabrication of structural parts where fibres are steered along curvilinear paths, namely variable angle tow (VAT), which can enhance the mechanical performance and alleviate the structural weight. This is of utmost importance in the aerospace field, where weight savings are one of the main goals. For that reason, shell structures are commonly found in the aerospace industry because of their capabilities of supporting external loadings. Straight-fibre composite shell structures have been studied in recent decades and, now, spatially varying composite shells are attracting the attention of manufacturers. This work analyses the mechanical behaviour of VAT composite shells subjected to different external loadings and boundary conditions. The Carrera Unified Formulation (CUF) is employed to obtain the different structural models in a systematic and hierarchic manner. The outcomes of such numerical models are discussed and compared with commercial software Abaqus.
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Wang, Huaqiao, Jihong Chen, Zhichao Fan, Jun Xiao, and Xianfeng Wang. "Experimental Investigation on the Influence of Fiber Path Curvature on the Mechanical Properties of Composites." Materials 14, no. 10 (May 17, 2021): 2602. http://dx.doi.org/10.3390/ma14102602.
Повний текст джерелаАнотація:
Automated fiber placement (AFP) has been widely used as an advanced manufacturing technology for large and complex composite parts and the trajectory planning of the laying path is the primary task of AFP technology. Proposed in this paper is an experimental study on the effect of several different path planning placements on the mechanical behavior of laminated materials. The prepreg selected for the experiment was high-strength toughened epoxy resin T300 carbon fiber prepreg UH3033-150. The composite laminates with variable angles were prepared by an eight-tow seven-axis linkage laying machine. After the curing process, the composite laminates were conducted by tensile and bending test separately. The test results show that there exists an optimal planning path among these for which the tensile strength of the laminated specimens decreases slightly by only 3.889%, while the bending strength increases greatly by 16.68%. It can be found that for the specific planning path placement, the bending strength of the composite laminates is significantly improved regardless of the little difference in tensile strength, which shows the importance of path planning and this may be used as a guideline for future AFP process.
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Hashimoto, Kenji, Kentaro Hattori, Takuya Otani, Hun-Ok Lim, and Atsuo Takanishi. "Foot Placement Modification for a Biped Humanoid Robot with Narrow Feet." Scientific World Journal 2014 (2014): 1–9. http://dx.doi.org/10.1155/2014/259570.
Повний текст джерелаАнотація:
This paper describes a walking stabilization control for a biped humanoid robot with narrow feet. Most humanoid robots have larger feet than human beings to maintain their stability during walking. If robot’s feet are as narrow as humans, it is difficult to realize a stable walk by using conventional stabilization controls. The proposed control modifies a foot placement according to the robot's attitude angle. If a robot tends to fall down, a foot angle is modified about the roll axis so that a swing foot contacts the ground horizontally. And a foot-landing point is also changed laterally to inhibit the robot from falling to the outside. To reduce a foot-landing impact, a virtual compliance control is applied to the vertical axis and the roll and pitch axes of the foot. Verification of the proposed method is conducted through experiments with a biped humanoid robot WABIAN-2R. WABIAN-2R realized a knee-bended walking with 30 mm breadth feet. Moreover, WABIAN-2R mounted on a human-like foot mechanism mimicking a human's foot arch structure realized a stable walking with the knee-stretched, heel-contact, and toe-off motion.
Книги з теми "Tow Angle Placement"
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Aspden, Richard, and Jenny Gregory. Morphology. Oxford University Press, 2016. http://dx.doi.org/10.1093/med/9780199668847.003.0011.
Повний текст джерелаАнотація:
The study of joint morphology can help us to understand the risk factors for osteoarthritis (OA), how it progresses, and aids in developing imaging biomarkers for study of the disease. OA results in gross structural changes in affected joints. Growth of osteophytes, deformation of joint components, and loss of joint space where cartilage has broken down are all characteristics of the disorder. Certain bone shapes as well as malalignment predispose people to future OA, or may be a marker for early OA. Geometrical measures, such as the alpha angle or Wiberg’s CE angle, used to be the primary tool for investigating morphology. In recent years, however, statistical shape modelling (SSM) has become increasingly popular. SSM can be used with any imaging modality and has been successfully applied to a number of musculoskeletal conditions. It uses sets of landmark points denoting the anatomy of one or more bones to generate new variables (modes) that describe and quantify the shape variation in a set of images via principal components analysis. With the aid of automated search algorithms for point placement, the use of SSMs is expanding and provides a valuable and versatile tool for exploration of bone and joint morphometry. Whilst the majority of research has focused on hip and knee OA, this chapter provides an overview of joint morphology through the whole skeleton and how it has helped our ability to understand and quantify the risk and progression of osteoarthritis.
2
Kahn, S. Lowell. Balloon Anchor Techniques for Sheath, Guide Catheter, and Stent Advancement and to Facilitate Chronic Total Occlusion Traversal. Edited by S. Lowell Kahn, Bulent Arslan, and Abdulrahman Masrani. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780199986071.003.0061.
Повний текст джерелаАнотація:
Advancement of a sheath or guide catheter into a small, diseased or angled branch vessel such as the superior mesenteric artery or renal artery can be difficult. Similarly, there are times when placement of a sheath up and over a sharply angulated aortic bifurcation can present a challenge. Obtaining a sheath position at or beyond a stenotic or occlusive lesion may be critical for delivering a stent, particularly with the inherent risk of dislodgment associated with balloon-expandable stents. The use of balloons as anchors has been described most commonly in the coronary vasculature, but it can have an important role in peripheral and visceral applications. This chapter discusses the utility of balloons as an anchor to advance a sheath or stent to a target location.
Частини книг з теми "Tow Angle Placement"
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Wittenstrom, Kim, Donald J. Baumann, John D. Fluke, J. Christopher Graham, and Joyce James. "The Impact of Drugs, Infants, Single Mothers, and Relatives on Reunification." In Decision-Making and Judgment in Child Welfare and Protection, 194–214. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780190059538.003.0009.
Повний текст джерелаАнотація:
Using a Decision-Making Ecology (DME) approach and proportional hazards models, the study reviewed in this chapter isolated four case factor profiles that interacted strongly with race and resulted in disparate reunification outcomes for African American children compared with Anglos. The four interrelated factors were drug involvement, a solo infant case, single mothers, and relative placements. A cohort of 21,763 children from the Texas Department of Family and Protective Services who were placed for the first time in care, who were under 13, and were either Anglo or African American were followed for 20 months or more post entry into care. Starting with an initial model consisting of main effects only and consistent with other studies, African American children had a 12% lower hazard rate of reunification compared to Anglo children. However, when a set of case profiles involving combinations of single parents, single infants, drug involvements, and kinship placements were crossed with race, the magnitude of the effect of race on hazard rates fanned out from no difference to as much as 68% that of Anglo children. The results show that racial disparities in outcomes resulting from complex, contextual decision-making cannot be modeled well with simple main effects models.
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Puigdellívol-Sánchez, Anna, Xavier Sala-Blanch, Miguel A. Reina, and Alberto Prats-Galino. "Anatomical Variability and Biomedical Imaging for Spinal Anesthesia Individualization." In Technological Adoption and Trends in Health Sciences Teaching, Learning, and Practice, 126–46. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-8871-0.ch006.
Повний текст джерелаАнотація:
Spinal anesthesia can be affected by gaps in the ligamentum flavum that may confuse epidural needle placement; cause Quincke needle deformation if the vertebral bone is hit, expanding the dural sac hole and leading to cerebrospinal fluid (CSF) leakage and post-dural puncture headache; and variability in CSF volume, altering intrathecal drug dilution and anesthetic efficacy. Paramedian approaches with previously calculated optimal angles can be adopted, and CSF volumes may be estimated using threshold selection within the grayscale range following anatomical criteria. Angles can be determined by previously quantifying the skin-dural sac distance using ultrasound. Here, the relevant anatomical structures are illustrated (ligaments, the ligamentum flavum gap, vertebrae, meninges, cauda equina roots) using a freely available 3D PDF tool (http://hdl.handle.net/2445/55225), the additional inconvenience of variability in vertebra rotation is quantified, a free guide for optimizing spinal puncture is presented (http://hdl.handle.net/2445/179594), and the possibility of individualizing intrathecal drug dosages is discussed.
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Boop, Frederick A., and Jimmy Ming-Jung Chuang. "Posterior Fossa Ependymoma." In Pediatric Neurosurgery, 223–30. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780190617073.003.0025.
Повний текст джерелаАнотація:
Pediatric posterior fossa ependymomas are typically well-delineated masses with heterogenous enhancement arising from the floor, lateral aspect, or roof of the fourth ventricle. Growth of tumor into the posterior fossa subarachnoid spaces, particularly into the foramen of Magendie and the cerebellopontine angles via the foramen of Luschka, is a radiological hallmark of this tumor. Clinical findings of elevated intracranial pressure and obstructive hydrocephalus are common at presentation. The current standard of care for children with ependymoma consists of gross total resection with subsequent focal radiotherapy. The extent of resection is the single most important determinant of outcome. Hydrocephalus typically resolves after resection, and it is uncommon to require cerebrospinal shunt placement after tumor removal.
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"Balancing Fisheries Management and Water Uses for Impounded River Systems." In Balancing Fisheries Management and Water Uses for Impounded River Systems, edited by William B. Jacobson and Kirk L. Koch. American Fisheries Society, 2008. http://dx.doi.org/10.47886/9781934874066.ch30.
Повний текст джерелаАнотація:
<em>Abstract</em>.—The Lake Havasu Fisheries Improvement Program was established in 1992 through the development of a partnership with all of the state, federal, and private organizations that hold an interest in improving the fisheries in Lake Havasu. As the 10-year program reached completion, the actual costs were half of the original estimate. Nonfederal sources provided more than 7 million dollars and the volunteer labor force contributed more than 170,000 h of service in the construction and placement of artificial structures. Angler satisfaction improved, even with a quadrupling of the angling pressure to the lake. Nearly 40 national and regional fishing tournaments returned Lake Havasu to their circuit schedule as a result of this program. The five recreational angling facilities provided free 24-h access to the lake for all ages and physical abilities. These facilities receive more than 80,000 angler use days per year. In addition to all of the sport fish activities, the program was able to re-establish populations of two federally listed endangered species of fish to the reservoir, ending a 20-year absence in the area. As a final accomplishment, the partnership signed a new memorandum of understanding that covers future coordinated maintenance and monitoring activities on the reservoir to sustain the benefits and document long-term results.
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Wang, Nan. "Tube Shunt Related Complications of the Cornea." In Complications of Glaucoma Surgery. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780195382365.003.0065.
Повний текст джерелаАнотація:
Tube shunts can be placed in the anterior chamber, the ciliary sulcus, or the pars plana. However, if the eye is phakic, the choice is limited to the anterior chamber; ciliary sulcus placement is likely to result in cataract formation, and pars plana placement will likely complicate removal of the cataract that will likely develop. Most corneal complications of tube shunt surgery result from tubes that are too anterior. Loss of vision may result due to these complications. If the tube is inadvertently inserted too close to the cornea, a loss of endothelial cells will result in edema and require transplantation to restore vision. Reported rates of corneal complications range from 2% to 33% and consist mostly of corneal edema/decompensation and corneal graft failure. In a cohort of patients implanted with the Ahmed™ Glaucoma Valve (New World Medical, Inc., Rancho Cucamonga, California), postoperative corneal abrasions occurred in 5 of 60 (8%) eyes. Another study reported the rate of corneal drying/dellen later in the postoperative course (8 of 59 eyes; 13.6%). Contact between the tube and the cornea has been noted at a rate of up to 5%. As the rate of tube shunt implantation has increased, the incidence of corneal edema in patients with tube shunts has also increased. Some of these cases develop corneal opacification with decreased vision and may require corneal transplantation to clear the visual axis. One large study of patients with Ahmed tube shunts (159 eyes total) reported corneal graft failure resulting in repeat penetrating keratoplasty (PKP) in 11 of 31 (35%) eyes with corneal grafts. Improper anterior chamber tube entry may damage the cornea. If the entry angle is not parallel to the iris and aims anteriorly, the needle used to create the tunnel may tear or detach Descemet’s membrane. Entry through the cornea (rather than the sclera) may also predispose to epithelial downgrowth or tube extrusion. To avoid such a complication, fullthickness entry into the anterior chamber should be as far posterior as possible.
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Patel, Sarosh R., and Tarek Sobh. "Optimal Design of Three-Link Planar Manipulators Using Grashof’s Criterion." In Prototyping of Robotic Systems, 70–83. IGI Global, 2012. http://dx.doi.org/10.4018/978-1-4666-0176-5.ch003.
Повний текст джерелаАнотація:
The design of robotic manipulators is dictated by a set of pre-determined task descriptions and performance parameters. These performance parameters are often defined in terms of workspace dexterity, manipulability, and accuracy. Many serial manipulator applications require that the manipulator have full dexterity about a work piece or a pre-defined trajectory, that is, to approach the given point within the workspace with all possible orientations about that point. Grashof’s criterion defines the mobility of four-link closed chain mechanisms in relation to its link lengths. A simple assumption can convert a three-link serial manipulator into a four-link closed chain so that its mobility can be studied using Grashof’s criterion. With the help of Grashof’s criterion, it is possible not only to predict and simulate the mobility of a manipulator during its design, but also to map and identify the fully-dexterous regions within its workspace. Mapping of the dexterous workspace is helpful in efficient task placement and path planning. Next, the authors propose a simple algorithm using Grashof’s criterion for determining the optimal link lengths of a three-link manipulator, in order to achieve full dexterity at the desired regions of the workspace. Finally, the authors test the generated design by applying joint angle limitations.
Тези доповідей конференцій з теми "Tow Angle Placement"
1
Luersen, M. A., C. A. Steeves, and P. B. Nair. "Optimisation of a Laminated Composite Cylindrical Shell With Curvilinear Fibre Paths Using a Surrogate-Based Approach." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36285.
Повний текст джерелаАнотація:
Conventional design and manufacturing techniques of fibre-reinforced laminated materials keep the fibre orientation angle constant within each ply. However, with the development of advanced tow-placement technology it is now feasible to produce composites with curved fibres. This offers more flexibility to tailor the mechanical properties and improve the performance of laminated structures. In this paper, fibre path optimisation of a laminated cylindrical shell is studied. Curvilinear variations for the fibre orientations are adopted in the circumferential and longitudinal directions of the shell. In order to reduce the computational cost a surrogate-based optimisation strategy is proposed to pursue the optimum design. The laminated shell is subjected to bending and torsion loads and the maximum displacement magnitude is minimised while a constraint on the buckling load is imposed. Numerical studies are presented for two cases. First, only circumferential variation in the fibre orientations is considered. Then, circumferential and longitudinal variations are assumed.
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DAGHIGHI, SHAHRZAD, and PAUL M. WEAVER. "FAILURE PERFORMANCE OF BEND-FREE VARIABLE STIFFNESS COMPOSITE PRESSURE VESSELS." In Thirty-sixth Technical Conference. Destech Publications, Inc., 2021. http://dx.doi.org/10.12783/asc36/35889.
Повний текст джерелаАнотація:
Pressure vessels are designed to store liquids and gases and have various applications spanning from chemical plants to automotive and aerospace industries. Currently, lightweight composite pressure vessels are desirable, especially in transportation industry applications because of their subsequent benefits in fuel consumption, cost and environmental issues. Using composite materials for pressure vessels along with advanced manufacturing technologies such as automated fiber placement provides excellent scope to tailor stiffness through the structural surface using fiber steering to achieve desirable structural performance. Recently, variable angle tow (VAT) technology has been used to suppress bending in super ellipsoids of revolution composite pressure vessels, resulting in minimizing the inefficient bending stresses and deformations and increasing their load-carrying capacity. It is worth noting that such geometries can provide excellent packing efficiency. These advantages make the bend-free super ellipsoids of revolution composite pressure vessels potential candidates for the next generation of pressure vessels. Therefore, their failure performance as the most important design factor should be studied carefully due to safety reasons. In this study, the maximum allowable internal pressure for VAT bend-free ellipsoidal pressure vessels, using the first-ply failure based on both Tsai-Wu and three-dimensional invariant-based failure criteria is determined. Subsequently, VAT bend-free pressure vessels’ failure performance is compared against that obtained for conventional constant stiffness composite vessels. Among structures considered, the VAT bend-free composite vessel has the best failure performance. Moreover, the predicted failure load using the three-dimensional invariant-based failure criterion for the VAT bend-free design is 34% lower than the failure load predicted by the Tsai- Wu. Finally, the effect of various material properties on the difference in predicted failure load using these criteria is assessed. Results provide physical insight useful for designers in materials selection.
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Vargas Rojas, Erik, David Chapelle, and Dominique Perreux. "Towards the Development of Filament Wound Composite Structures Submitted to Very High Internal Pressure, Based on Complex Geometry Shapes." In ASME 2013 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/pvp2013-97418.
Повний текст джерелаАнотація:
Industrial applications, especially composite structures bearing high internal pressure, and fabricated using the filament winding process face certain difficulties like the reinforcement of complex shapes, as well as the correct placement of fibers over the surface of a mandrel. In some cases the definition of the manufacturing parameters respond more to cost or time criteria rather than engineering standards, reducing largely the advantages of the said manufacturing process. In order to overcome these obstacles, this research aims to propose a solution that permits to fabricate complex shapes with the desired winding angles at a certain region of complex-shaped mandrels. A numerical tool that simulates the placement of fiber tows over the surface of complex geometries is developed and validated by means of the fabrication of convex and concave composite structures using detachable mandrels. Previous results show that it is feasible to wind complex geometries with good accuracy.
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Hursan, Gabor, and Marie Van Steene. "Real-Time Facies Characterization Using LWD NMR Factor Analysis in High-Angle Wells." In Middle East Oil, Gas and Geosciences Show. SPE, 2023. http://dx.doi.org/10.2118/213773-ms.
Повний текст джерелаАнотація:
Abstract Nuclear magnetic resonance (NMR) logs in long, high-angle wells drilled across a single reservoir often consist of a few recurring features which are difficult to identify visually in the NMR T2 distribution logs. This paper presents a fast data clustering method called NMR factor analysis (NMRFA) that categorizes massive LWD NMR datasets into a few poro-fluid facies, which enables a quick, data-driven geological interpretation using single or multiple wells. NMRFA is a data reduction technique that aims to describe and interpret variability in NMR spectral logs using a small number of unique components. These components are clustered statistically to distinct groups called poro-fluid facies, which reflect combinations of pore volume, pore size, and fluid NMR properties. While drilling the well, the NMRFA is applied to the real-time T2 distribution measurements to quickly associate new observations of rock quality or heavy oil with stratigraphic understanding to assist well placement decisions. Joint interpretation of the NMR-based para-fluid facies logs from multiple laterals underpins data-driven updates of reservoir-scale geological facies maps. After testing the method on two data sets already calibrated to core and formation testing measurements, the NMRFA technique was used in three laterals drilled back-to-back in a thin carbonate where pore size variations and possible presence of heavy oil were expected. In the first lateral, the best NMR facies were mostly observed in the first part of the well, followed by poorer poro-fluid facies that indicated the presence of heavy oil. At the end of the well, the facies analysis indicated mostly tight rocks. In the second lateral, the NMR log suggested a more homogeneous facies distribution than in the first well, with medium T2 and medium porosity. Tar or heavy oil were not encountered in this well. With the facies trends in the first two wells, the third lateral targeted a likely occurrence of the high-quality facies seen in the top section of the first well. After crossing a tight zone, this well encountered an excellent NMR facies of high porosity and very long T2 with no indications of heavy oil. The well was successfully navigated within the favorable facies whose quality matched or exceeded the best rocks encountered by the first two laterals. NMRFA analysis was used for poro-fluid facies evaluation of LWD NMR datasets in real-time settings for the first time to better categorize complex reservoir types in horizontal wells. The robust, data-driven analysis method and its intuitive log-based and structural visualizations helped well placement decisions and enhanced structural learnings in three extended reach laterals drilled in a complex carbonate reservoir.
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Gao, Chuang, Chuangang Gu, Tong Wang, and Bo Yang. "Passive Control of Rotating Stall in Vaneless Diffuser With Radial Grooves: Detailed Numerical Study." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59323.
Повний текст джерелаАнотація:
According to experiments described in the literature, radial grooves in vaneless diffuser walls are simple and powerful devices for suppressing rotating stall. To understand the mechanism behind the grooves and find some guidelines for diffuser designers, a detailed numerical study based on Computational Fluid Dynamics (CFD) was carried out. Not only the flow field variation caused by the grooves but also a simple model graphing the underlying nature was established. Also, the classic boundary layer integral method widely used in practical design procedure was adopted to calculate the diffuser flow distribution to verify the model. The CFD analysis indicated that the effectiveness of the grooves increases the flow angle thus delaying the diffuser wall flow reversals. The recommended placement of the grooves was in the region with reversed flow. Such locally fixed groove could effectively delay the stall without too much pressure loss. Also, a combined variable, representing the overall geometry of grooves was established and verified. The detailed study given in this paper gives guidelines for using grooves as a stall delay method.
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Sie, Astrini, Jonathan Realmuto, and Eric Rombokas. "A Lower Limb Prosthesis Haptic Feedback System for Stair Descent." In 2017 Design of Medical Devices Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/dmd2017-3409.
Повний текст джерелаАнотація:
Though there are a variety of prosthetic limbs that address the motor deficits associated with amputation, there has been relatively little progress in restoring sensation. Prosthetic limbs provide little direct sensory feedback of the forces they encounter in the environment, but “closing the loop” between sensation and action can make a great difference in performance [1]. For users of lower limb prostheses, stair descent is a difficult and dangerous task. The difficulty in stair descent can be attributed to three different factors: 1) Absence of tactile and haptic sensations at the bottom of the foot. Although force on the prosthetic socket provides some haptic feedback of the terrain being stepped on, this feedback does not provide information on the location of the staircase edge. 2) Insufficient ankle flexion of lower limb prostheses. Dorsiflexion of the physiological ankle during stair descent is about 27°. Even prostheses that provide active dorsiflexion provide less than this number, and regular prostheses provide almost no ankle dorsiflexion. The first two factors are analogous to the sensation of stair descent for someone without amputation wearing ski boots. 3) Prosthetic feet are optimized for flat-ground walking, offering undesirable energy storage at ankle flexion and energy return at toe-off. This can result in unwanted extra energy at the end of stance phase, propelling the user forward down the stairs. Most lower limb prosthesis designs focus on flat ground walking, but there has been less progress in addressing the challenges of stair descent. One technique that users of prosthetic lower limbs can use for addressing these challenges is to employ an “overhanging toe” foot placement strategy. Under this strategy, the edge of the staircase is used as a pivot point for the foot to roll over the stair. This reduces the need for ankle flexion by allowing the knee and hip to compensate, and avoids storing energy in the prosthetic spring. This strategy is dynamic, and requires the user to know the amount of toe overhang to adjust the movement of the rest of the body. Most haptic devices built to assist individuals wearing prostheses focus on upper extremity tasks [2–4] or standing and walking [5,6]. Whereas previous lower limb sensory replacement systems have targeted standing measures, here we focus on stair descent. The system provides cues of the stair edge location via vibrotactile stimulations on the thigh.
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Liu, Wubo, Xiaofei Gao, Qingquan Li, Yi Guo, Lei Yu, Chao Wang, Botao Chang, Fei Wang, Shuzhong Li, and Yen Han Shim. "Enhancing Oil Recovery in a Brown Oilfield of Offshore South China." In Offshore Technology Conference Asia. OTC, 2022. http://dx.doi.org/10.4043/31365-ms.
Повний текст джерелаАнотація:
Abstract Located in offshore South China, XJ oil field entered the mature development phase after more than 20 years of production, with the water cut of the field increasing to 93%. A new strategy was executed starting in 2018 that targeted the remaining oil column, which was being squeezed by a strong bottomwater. One of the biggest challenges was the high uncertainty of the oil/water contacts in the current reservoir state. After reviewing the technical and geological challenges encountered, we will describe the successful approach taken to optimize the remaining reserves recovery using innovative horizontal well placement strategies. Using a few case studies, we will illustrate how we executed this innovative well placement strategy. This includes landing the horizontal wells at the upper part of the reservoir with low incident angle, drilling the horizontal sections close to the top of target zones using a reservoir boundary detection tool, and using a continuous packer for the well completion to reduce the water cut. In addition, we will describe how the team evaluated and selected logging technologies in the planning phase for proper well placement. The two cases discussed in this paper are based on horizontal wells completed using the following new strategy: maintaining a long lateral section in the upper layer of a predefined target, following the undulating structure while mapping the thin sandstone, keeping the trajectory in the target zone, etc. To ensure that each horizontal well could meet the target productivity index planned, real-time data were used in reservoir modeling to determine the required lateral length of each horizonal well. With the purpose of controlling water cut and improving oil recovery in these laterals, a new completion assembly, including a perforated liner with special completion material that prevented water from entering the liners, were installed in selected intervals according the logging data interpretation. Several observations will be highlighted, including: Real-time logging data can effectively evaluate the reservoir properties and structural changes along the lateral Optimum well placement in the lateral section is critical for draining the remaining oil column An optimized completion design based on real-time reservoir evaluation. The performance of the wells drilled to date shows that the production increased from 1,000 to 3,000 BOPD with zero to very low water cut. A reversing production trend from a declining trend to a growth trend is recorded. The successful implementation of the new strategy and the application of fit-for-purpose technologies in mature oil fields lead to improved production and increased oil recovery.
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Kolle, Jack, Alan Mueller, Steve Baumgartner, and David Cuthill. "Modeling Proppant Transport in Casing and Perforations Based on Proppant Transport Surface Tests." In SPE Hydraulic Fracturing Technology Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/209178-ms.
Повний текст джерелаАнотація:
Abstract The results of a series of proppant transport surface tests (PTSTs) were used in conjunction with Eulerian multiphase-computational fluid dynamics (EMP-CFD) modeling to develop an engineering model of proppant distribution. The PTSTs were carried out to evaluate proppant placement through perforated casing. In these tests, sand slurry was pumped at realistically high flow rates through perforated casing and the distribution of sand and slurry from each perforation cluster was observed. The tests show that gravitational settling in horizontal casing, proppant slip past perforations and the visco-elastic properties of slickwater fluids strongly affect the distribution of proppant from the heel to the toe of the completion. The EMP-CFD modeling was used to estimate the gravitational settling of sand in fully-developed turbulent slurry flow in horizontal casing as a function of casing velocity. A survey of 36 calculations was carried out to generate tables of sand concentration in a cross section through the casing as a function of flow rate and particle size. A single-phase CFD analysis showed how sand exiting each perforation is taken from a limited ingestion area which is proportional to the ratio of flow through the perforation to total flow in the casing. A detailed EMP-CFD analysis of flow through single perforations showed how sand slips past the perforation. The results of 28 EMP-CFD calculations provided slip factors as a function of particle size, casing flow velocity, and perforation flow velocity in straight and angled perforations. The EMP-CFD settling tables and a parameterization of the slip factors were integrated into an engineering model. The model predicts the distribution of slurry and sand through each perforation based on the proppant size, perforation phase angle, and pump rate. The engineering model was used to predict the sand distributions observed in the PTSTs. The PTSTs were conducted with a range of sand sizes and with low-viscosity friction reducing polymer (FR) additives, while the EMP-CFD analysis assumed water. A weight factor is introduced in the settling model to account for the increased dispersion of sand in water with low viscosity FR and to match the observed sand distributions in the PTSTs. The observed slip of 100 Mesh and 40/70 Mesh sand is consistent with the EMP-CFD calculations in water. The model reflects the PTST observations that fine sand is distributed relatively uniformly throughout the length of a perforated completion while coarser sand tends to slip past the heel perforations and concentrate on the bottom towards the toe of the completion.
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Kovarskiy, Egor, Guillermo Cuadros, Zoriana Snovida, Eliana Beltran, and Ettore Mirto. "Improving Reservoir Exposure in Thin Heterogeneous Carbonera Formation With the New Multilayer Mapping-While-Drilling Technology: A Case Study." In 2022 SPWLA 63rd Annual Symposium. Society of Petrophysicists and Well Log Analysts, 2022. http://dx.doi.org/10.30632/spwla-2022-0061.
Повний текст джерелаАнотація:
Geological uncertainties and operational risks are factors which, when not addressed properly, can jeopardize the results of a horizontal drilling campaign. However, with the use of modern multilayer mapping geosteering technologies, the success rate of such projects can be greatly improved. This paper focuses on dealing with geosteering challenges faced in the Carbonera formation of Llanos basin in Colombia. It is one of the most important reservoirs in Colombia and is largely developed through horizontal drilling with more than 90 horizontal wells drilled in the last 12 months. This reservoir is characterized by thinness, heterogeneity, presence of the oil-water contact (OWC), and lateral discontinuity. Moreover, a considerable amount of iron carbonate in the upper part of this formation presents an additional challenge during the landing phase, since it requires arriving to the formation top at the maximum possible angle to avoid bouncing the bottomhole assembly (BHA) back into the siderite levels located above the target. This case study shows how the use of a new multilayer mapping-while-drilling technology helped increase net-to-gross ratio and reduce the risk of unproductive drilling in the Carbonera formation. The improvement is achieved through the addition of new deep bulk resistivity and anisotropy measurements to the set of electromagnetic measurement used in legacy bed boundary mapping logging-while-drilling (LWD) technologies. This enriched set of curves incorporated into a novel deterministic inversion algorithm enables an enhanced layer continuity with higher resolution boundary mapping and double depth of detection. This increase in resolution and depth of detection leads to highly accurate geosteering in those shallow reservoirs. It is demonstrated that well placement optimization in the Carbonera formation is achieved during both landing and horizontal drilling phases. The gain in depth of detection allows detecting the formation top earlier when landing and avoiding stopping drilling prematurely due to discontinuities of target layer, thus increasing reservoir exposure. In turn, higher resolution capability helps to better control well trajectory with respect to OWC position, which consequently increases net-to-gross ratio and reduce the risk of unproductive drilling. Obtained experience can be expanded to other fields with similar needs for geosteering optimization.
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Soloiu, Valentin, Jose Moncada, Remi Gaubert, Spencer Harp, Marcel Ilie, and Justin Wiley. "GTL Kerosene and N-Butanol in RCCI Mode: Combustion and Emissions Investigation." In ASME 2018 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/icef2018-9585.
Повний текст джерелаАнотація:
High reactivity gas-to-liquid kerosene (GTL) was investigated with port fuel injection (PFI) of low reactivity n-butanol to conduct reactivity controlled compression ignition (RCCI). In the preliminary stage, the GTL was investigated in a constant volume combustion chamber, and the results indicated a narrower negative temperature coefficient (NTC) region than ultra-low sulfur diesel (ULSD#2). The engine research was conducted at 1500 RPM and various loads with early n-butanol PFI and dual DI pulses of GTL at 60 crank angle degrees (CAD) before top dead center (TDC) and at a timing close to TDC. Boost and PFI fractions (60% by mass n-butanol) were kept constant in order to analyze the fuel reactivity effect on combustion. Conventional diesel combustion (CDC) mode with a single injection and the same combustion phasing (CA50) was used as an emissions baseline for RCCI. RCCI increased ignition delay and combustion duration decreased compared to CDC. Results showed that in order to maintain CA50 for RCCI within 1 CAD, GTL mass required for the first DI pulse to be 15% lower than that of ULSD#2 at higher loads. Peak heat release rate decreased for GTL by 25% given the high volatility and low viscosity of GTL. In general, using GTL, NOx and soot levels were reduced across load points by up to 15% to 30%, respectively, compared to ULSD RCCI, while maintaining RCCI combustion efficiency at 93–97%. Meanwhile, reductions of 85% in soot and 90% in NOx were determined when using RCCI compared to CDC. The more favorable heat release placement of GTL led to increased thermal efficiency by 3% at higher load compared to ULSD#2. The higher volatility and increased reactivity for GTL achieved lower UHC and CO than ULSD#2 at lower load. The study concluded that GTL offered advantages when used with n-butanol for this RCCI fueling configuration.