Academic literature on the topic 'Pitching WEC'
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Journal articles on the topic "Pitching WEC"
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Li, Biao, Fangfang Sui, and Bingsong Yang. "An efficient multi-factor geometry optimization based on motion analysis and resonance response for hinged double-body floating wave energy converter." Science Progress 103, no. 3 (July 2020): 003685042095015. http://dx.doi.org/10.1177/0036850420950151.
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In the practical engineering applications of multi-body floating wave energy converter (WEC), the traditional geometric optimization is always expensive and time-consuming. This study aim to propose a more efficient geometry optimization strategy with a hinged double-body floating WEC as the study object. The influences of geometric parameters of the buoys on the pitching motion and energy conversion ability are analyzed by numerical simulation. Simulation results show that the resonance state of the pitching motion of the buoys mainly depends on their radius and draft rather than the length; But the length of the buoys, rather than the radius and draft, always has a significant effect on the pitching phase difference of the adjacent buoys. Based on the motion analysis and resonance response, an efficient multi-factor geometry optimization strategy is put forwarded. By the strategy, the sub-optimal and optimal geometrical parameters are solved out quickly at several typical wave conditions of China Seas. The results indicate that the optimal total length of WEC is approximately equal to the wave length. The optimal diameter of buoys is about 25% of the length of buoys. And the optimal draft should attain about 61% of the diameter.
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Chen, Hailong, Fankai Kong, Hengxu Liu, Weiming Su, Dan Yu, and Weiqi Liu. "Investigation on semi-analytical solution of dynamic characteristics of an anti-pitching generating WEC (AG-WEC)." Journal of Marine Science and Technology 25, no. 4 (February 19, 2020): 1129–50. http://dx.doi.org/10.1007/s00773-020-00705-w.
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Hantoro, Ridho, Erna Septyaningrum, Yusuf Rifqi Hudaya, and I. Ketut Aria Pria Utama. "STABILITY ANALYSIS FOR TRIMARAN PONTOON ARRAY IN WAVE ENERGY CONVERTER – PENDULUM SYSTEM (WEC - PS)." Brodogradnja 73, no. 3 (July 1, 2022): 59–68. http://dx.doi.org/10.21278/brod73304.
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Ocean waves are a renewable energy source with abundant reserves in Indonesia. With the vast waters of Indonesia, the development of a sea wave power plant needs to be developed. This research focuses on the development of easy-operated and maintained ocean wave converter–pendulum system (OWC – PS). The numerical simulation and experimental analysis were conducted to obtain the relation between the motion response of the pontoon array and its pendulum. The pontoon used is the trimaran type, which consists of a cylindrical pontoon as the main hull and two outriggers on its side. This study analyses the most stable array arrangement that produces maximum pitching motion and pendulum deviation. The simulation results show that the largest pitching value is in array 1, i.e., 27.91° for pontoon 1 and 38.92° for pontoon 2, which results in a maximum pendulum deviation of 100 ° for pendulums 1 and 56.2 ° for pendulum 2 over a wave period of 9 seconds. The backward motion of the pendulum in both array configurations tends to have a greater deviation than that of the forward motion. The pendulums of array 1 have different motion characteristics, represented by different deviation values in both pendulums. This phenomenon does not occur in array 2, since both pendulums in array 2 have the same deviation (with only a small discrepancy).
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Yu, Dan, Keyi Wang, Hengxu Liu, Fankai Kong, Can Yang, Yupeng Duan, and Hailong Chen. "Investigation on motion characteristics of an Anti-pitching Generating WEC (AGWEC) considering the viscous effect." Ocean Engineering 246 (February 2022): 110619. http://dx.doi.org/10.1016/j.oceaneng.2022.110619.
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Guo, Baoming, Dezhi Ning, Rongquan Wang, and Boyin Ding. "Hydrodynamics of an oscillating water column WEC - Breakwater integrated system with a pitching front-wall." Renewable Energy 176 (October 2021): 67–80. http://dx.doi.org/10.1016/j.renene.2021.05.056.
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Poguluri, Sunny Kumar, Il-Hyoung Cho, and Yoon Hyeok Bae. "A Study of the Hydrodynamic Performance of a Pitch-type Wave Energy Converter–Rotor." Energies 12, no. 5 (March 4, 2019): 842. http://dx.doi.org/10.3390/en12050842.
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The effect of hydrodynamic performance of the wave energy converter (WEC)–rotor based on linear potential flow theory due to nonlinear viscous damping was investigated. Free decay tests were conducted using computational fluid dynamics (CFD) to obtain the viscous damping moment. The commonly used procedure for obtaining the damping moment is based on peak amplitudes which normally require a long time history records. Such long free decay records may not be possible in nodding WEC rotor due high damping. The energy method proposed by Bass and Haddara requires only the short and full range of the recorded data. This method provides sufficiently good results when the bodies have high damping. The method equates the rate of change of the total energy of a body undergoing free rolling/pitching to the rate of energy dissipated by the damping. The present study adopts a similar methodology for estimating the linear and linear plus quadratic damping. To incorporate the nonlinear viscous damping moment in the linear equation of motion, an equivalent linearization concept is used without neglecting the nonlinear damping effects. The hydrodynamic coefficients obtained from the linear potential flow theory, nonlinear viscous damping moment from the energy method and estimated PTO damping are used to solve the equation of motion of the WEC rotor. The estimated pitch free decay data shows good agreement with the simulated CFD results when compared to the linear viscous damping moment and better agreement is obtained with linear plus quadratic viscous damping moment. The regular and irregular wave analyses show that a considerable effect on the hydrodynamic performance of the WEC rotor is observed when the linear and linear plus quadratic viscous damping are included.
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McNatt, J. Cameron, Aaron Porter, and Kelley Ruehl. "Comparison of Numerical Methods for Modeling the Wave Field Effects Generated by Individual Wave Energy Converters and Multiple Converter Wave Farms." Journal of Marine Science and Engineering 8, no. 3 (March 3, 2020): 168. http://dx.doi.org/10.3390/jmse8030168.
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This numerical study compares the wave field generated by the spectral wave action balance code, SNL-SWAN, to the linear-wave boundary-element method (BEM) code, WAMIT. The objective of this study is to assess the performance of SNL-SWAN for modeling wave field effects produced by individual wave energy converters (WECs) and wave farms comprising multiple WECs by comparing results from SNL-SWAN with those produced by the BEM code WAMIT. BEM codes better model the physics of wave-body interactions and thus simulate a more accurate near-field wave field than spectral codes. In SNL-SWAN, the wave field’s energy extraction is modeled parametrically based on the WEC’s power curve. The comparison between SNL-SWAN and WAMIT is made over a range of incident wave conditions, including short-, medium-, and long-wavelength waves with various amounts of directional spreading, and for three WEC archetypes: a point absorber (PA), a pitching flap (PF) terminator, and a hinged raft (HR) attenuator. Individual WECs and wave farms of five WECs in various configuration were studied with qualitative comparisons made of wave height and spectra at specific locations, and quantitative comparisons of the wave fields over circular arcs around the WECs as a function of radial distance. Results from this numerical study demonstrate that in the near-field, the difference between SNL-SWAN and WAMIT is relatively large (between 20% and 50%), but in the far-field from the array the differences are minimal (between 1% and 5%). The resultant wave field generated by the two different numerical approaches is highly dependent on parameters such as: directional wave spreading, wave reflection or scattering, and the WEC’s power curve.
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Pirrung, Georg Raimund, and Helge Aagaard Madsen. "Dynamic inflow effects in measurements and high-fidelity computations." Wind Energy Science 3, no. 2 (August 22, 2018): 545–51. http://dx.doi.org/10.5194/wes-3-545-2018.
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Abstract. A wind turbine experiences an overshoot in loading after, for example, a collective step change in pitch angle. This overshoot occurs because the wind turbine wake does not immediately reach its new equilibrium, an effect usually referred to as dynamic inflow. Vortex cylinder models and actuator disc simulations predict that the time constants of this dynamic inflow effect should decrease significantly towards the blade tip. As part of the NASA Ames Phase VI experiment, pitch steps have been performed on a turbine in controlled conditions in the wind tunnel. The measured aerodynamic forces from these experiments seemed to show much less radial dependency of the dynamic inflow time constants than expected when pitching towards low loading. Moreover the dynamic inflow effect seemed fundamentally different when pitching from low to high loading, and the reason for this behavior remained unclear in previous analyses of the experiment. High-fidelity computational fluid dynamics and free-wake vortex code computations yielded the same behavior as the experiments. In the present work these observations from the experiments and high-fidelity computations are explained based on a simple vortex cylinder wake model.
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Wu, Chih-Hua Keni, and Vinh-Tan Nguyen. "Aerodynamic simulations of offshore floating wind turbine in platform-induced pitching motion." Wind Energy 20, no. 5 (November 2, 2016): 835–58. http://dx.doi.org/10.1002/we.2066.
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Lennie, Matthew, David Marten, George Pechlivanoglou, Christian Navid Nayeri, and Christian Oliver Paschereit. "Modern methods for investigating the stability of a pitching floating platform wind turbine." Wind Energy Science 2, no. 2 (December 22, 2017): 671–83. http://dx.doi.org/10.5194/wes-2-671-2017.
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Abstract. The QBlade implementation of the lifting-line free vortex wake (LLFVW) method was tested in conditions analogous to floating platform motion. Comparisons against two independent test cases using a variety of simulation methods show good agreement in thrust forces, rotor power, blade forces and rotor plane induction. Along with the many verifications already undertaken in the literature, it seems that the code performs solidly even in these challenging cases. Further to this, the key steps are presented from a new formulation of the instantaneous aerodynamic thrust damping of a wind turbine rotor. A test case with harmonic platform motion and collective blade pitch is used to demonstrate how combining such tools can lead to a better understanding of aeroelastic stability. A second case demonstrates a non-harmonic blade pitch manoeuvre showing the versatility of the instantaneous damping method.
Dissertations / Theses on the topic "Pitching WEC"
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Afonja, Adetoso J. "Dynamics of Pitching Wave Energy Converter with Resonant U-Tank Power Extraction Device." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/98782.
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This research revolves around the concept design and theoretical validation of a new type of wave energy converter (WEC), comprising a pitching floater integrated with a resonant U-tank (RUT) and a Wells turbine as power take-off (PTO). Theoretical formulation of a fully coupled multi-body dynamic system, incorporating the thermodynamic processes of the RUT air chamber, its interaction with the PTO dynamics and their coupling with the floater is presented.
Inaccuracies of the dynamic modeling of RUT based on Lloyd's low order model, which assumes constant hydrodynamic parameters irrespective of the frequency, are demonstrated by a series of high fidelity CFD simulations. These simulations are a systematic series of fully viscous turbulent simulations, using unsteady RANSE solvers, of the water sloshing at different frequencies of oscillation. Calibration of Lloyd’s model with CFD results evidenced that the RUT hydrodynamic parameters are not invariant to frequency.
A numerical model was developed based on Simulink WEC-Sim libraries to solve the non-linear thermo-hydrodynamic equations of the device in time domain. For power assessment, parametric investigations are conducted by varying the main dimensions of the RUT and power RAOs were computed for each iteration.
Performance in irregular sea state are assessed using a statistical approach with the assumption of linear wave theory. By superimposing spectrum energy density from two resource sites with RAO, mean annual energy production (MEAP) are computed. The predicted MEAP favorably compares with other existing devices, confirming the superior efficiency of the new proposed device over a larger range of incident wave frequency.M.S.
This study present results of an investigation into a new type of wave energy converter which can be deployed in ocean and by its pitch response motion, it can harvest wave energy and convert it to electrical energy. This device consist of a floater, a U-tank (resonant U-tank) with sloshing water free to oscillate in response to the floater motion and a pneumatic turbine which produces power as air is forced to travel across it. The pneumatic turbine is used as the power take-off (PTO) device. A medium fidelity approach was taken to carry out this study by applying Lloyd’s model which describes the motion of the sloshing water in a resonant U-tank. Computational fluid dynamics (CFD) studies were carried out to calibrate the hydrodynamic parameters of the resonant U-tank as described by Lloyd and it was discovered that these parameters are frequency dependent, therefore Lloyd’s model was modelled to be frequency dependent. The mathematical formulation coupling the thermodynamic evolution of air in the resonant U-tank chamber, modified Lloyd’s sloshing water equation, floater dynamics and PTO were presented for the integrated system. These set of thermo-hydrodynamic equations were solved with a numerical model developed using MATLAB/Simulink WEC-Sim Libraries in time domain in other to capture the non-linearity arising from the coupled dynamics. To assess the annual energy productivity of the device, wave statistical data from two resource sites, Western Hawaii and Eel River were selected and used to carrying out computations on different iterations of the device by varying the tank’s main dimensions. This results were promising with the most performing device iteration yielding mean annual energy production of 579 MWh for Western Hawaii.
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PAN, CHUN-JUNG, and 潘俊榮. "The Pitching Strategy in the Professional Baseball PitcherA Case Study of Wei-Lun Pan." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/16234475802619820304.
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碩士國立臺南大學
體育學系碩士班
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The purpose of this study is to analysis the pitching strategy of outs and extra base hits of the professional baseball pitcher, Wei-Lun Pan, with video provided by FOX and VL during the game season in 2015. Eight games were randomly selected and the researcher recorded with baseball squared record forms with two certified coaches. The results revealed that Pan seldom took outs by himself but reliant on his defensive team-mates. The strategies of taking outs were that (1)throw fastballs and sinkers as mainly pitches, good movement off the plate making hitters stand out; (2)high ball pitches with accurate positions of the strike zone; (3)vertical pitches making the gap of the positions; (4)increase the pitches which work the hitters; (5)the first pitch strike. Whereas the strategies of making extra base hits were that (1)the pitch falls down the middle or higher of the strike zone; (2)the pitches falls horizontally in the strike zone; (3)repeated pitch for due ups; (4) monotonous pitches; (5)use the same strategy on different type of hitters. Good pitchers not only need high speed and good control ability, but also need proper pitching strategy to deal with hitters. This case study provides some pitching strategies to coaches and players. It will be more valuable to analyze main pitchers in each team in the future studies.
Books on the topic "Pitching WEC"
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Faber, Richard B., and Charles F. Faber. Spitballers: The Last Legal Hurlers of the Wet One. McFarland & Company, Inc., Publishers, 2006.
Find full textBook chapters on the topic "Pitching WEC"
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Nguyen, H. P., C. M. Wang, and D. M. Pedroso. "A Pitching WEC-Type Attachment for Extracting Wave Energy and Reducing Hydroelastic Response of VLFS." In Lecture Notes in Civil Engineering, 199–207. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-7603-0_21.
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Alcorta de Bronstein, A., and J. M. Timm. "Transformational Sustainability Entrepreneurship: Encouraging Students to Become Real Change Agents." In Transforming Entrepreneurship Education, 67–86. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-11578-3_5.
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AbstractEntrepreneurial Education needs to be transformed. Our seminar called Transformational Sustainability Entrepreneurship aims at meeting this need by guiding students to become change agents for tackling the grand societal challenges of our time. In this chapter, we explain the five fundamental aspects in which this seminar is designed for students’ transformational learning experience. The seminar itself is divided into three phases: Understanding, Creative Thinking, and Pitching with an overarching reflection process. We introduce the concept, which we have been using for four years at two different universities, for others to apply and use in their own teaching activities.
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Rusko, Rauno, Katja Härkönen, and Sofia Petäjäniemi. "Pitching and the Other International Practices of Innovation Competitions." In Advances in Business Strategy and Competitive Advantage, 124–50. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-0953-0.ch007.
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This chapter focuses on the international practices of innovation competitions. Pitching is a truly global phenomenon in the education and youth entrepreneurship, which has similar structures and contents all over the world. Thus, this international practice follows the ideas of Ohmae (1990) about the borderless world. In other words, the micro-activities and the practices of innovation events are following the joint global macro-level frameworks and practices. However, there seems to be slight differences of these events basing on how these events are named or marketed in the Web. Some of these events are web-based while others involve face-to-face happenings. All these forms of pitching events provide important channel for young entrepreneurship. This chapter focuses on the international practices of innovation competitions. Pitching is a truly global phenomenon in the education and youth entrepreneurship, which has similar structures and contents all over the world. Thus, this international practice follows the ideas of Ohmae about the borderless world. In other words, the micro-activities and the practices of innovation events are following the joint global macro-level frameworks and practices. However, there seems to be slight differences of these events basing on how these events are named or marketed in the Web. Some of these events are web-based while others involve face-to-face happenings. All these forms of pitching events provide important channel for young entrepreneurship.
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Pournelle, Jerry. "Dealing with Spam." In 1001 Computer Words You Need to Know. Oxford University Press, 2004. http://dx.doi.org/10.1093/oso/9780195167757.003.0012.
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If you’ve used e-mail for any time at all, you’ve no doubt had your inbox deluged with messages pitching aphrodisiacs, mortgages, junk stocks, pornography, and substances that claim to help you lose weight in your sleep. But don’t despair. Such messages don’t have to be part of the Internet experience. You can avoid them, or certainly reduce the annoyance level, with a few simple measures. Some spammers harvest e-mail addresses from the Internet by using a “spider” (also known as a robot or crawler)—a computer program that creeps through the World Wide Web collecting information you’d prefer to keep private. So the better you are at hiding your address from faceless prowlers, the less spam you will receive. 1. If your Internet Service Provider gives you the choice, create a long, fairly complicated address preceding the @; don’t just use your first name: donquixote@example.com is better than don@example.com. Better still is donquixotedelamancha@example. com. It may be unwieldy, but your friends can always use a nickname—or just click on your address. Happily, longer addresses confuse spammers, who—without having exact user accounts in hand—use a “dictionary attack” to find them, testing the validity of every possible address from lists of common words and names: arline@example.com, barbara@example.com, and so forth. 2. Again, unless some online service makes it mandatory, don’t use your e-mail address as part of a login name or identity. However convenient that might make it when logging in to eBay, it’s equally convenient for spammers. 3. Use a second, public address for nonpersonal mail and for public posting. Create a free account with Hotmail, Yahoo, or Excite, or set up another screen name if you use either AOL or another Internet Service Provider that allows you to have multiple addresses. This keeps your main address private and exposes only your public address to spammers. Check the public account at least occasionally, in case something innocent has come in. Then massively delete the rest. It’s important to learn how your e-mail client (the program you use to send and receive e-mail) handles thorough deleting; in Outlook Express, for example, you have to delete an e-mail you don’t want from your inbox, delete it from the “Deleted” folder, and then compact folders before you are genuinely rid of it.
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Owen, Robert S. "Use of the Secondary Task Technique for Tracking User Attention." In Encyclopedia of Human Computer Interaction, 673–79. IGI Global, 2006. http://dx.doi.org/10.4018/978-1-59140-562-7.ch101.
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The notion that the human information processing system has a limit in resource capacity has been used for over 100 years as the basis for the investigation of a variety of constructs and processes, such as mental workload, mental effort, attention, elaboration, information overload, and such. The dual task or secondary task technique presumes that the consumption of processing capacity by one task will leave less capacity available for the processing of a second concurrent task. When both tasks attempt to consume more capacity than is available, the performance of one or both tasks must suffer, and this will presumably result in the observation of degraded task performance. Consider, for example, the amount of mental effort devoted to solving a difficult arithmetic problem. If a person is asked to tap a pattern with a finger while solving the problem, we might be able to discover the more difficult parts of the problem solving process by observing changes in the performance of the secondary task of finger tapping. While a participant is reading a chapter of text in a book or on a Web browser, we might be able to use this same technique to find the more interesting, involving, or confusing passages of the text. Many implementations of the secondary task technique have been used for more than a century, such as the maintenance of hand pressure (Lechner, Bradbury, & Bradley, 1998; Welch, 1898), the maintenance of finger tapping patterns (Friedman, Polson, & Dafoe, 1988; Jastrow, 1892; Kantowitz & Knight, 1976), the performance of mental arithmetic (Bahrick, Noble, & Fitts, 1954; Wogalter & Usher, 1999), and the speed of reaction time to an occasional flash of light, a beep, or a clicking sound (e.g., Bourdin, Teasdale, & Nourgier, 1998; Owen, Lord, & Cooper, 1995; Posener & Bois, 1971). In using the secondary task technique, the participant is asked to perform a secondary task, such as tapping a finger in a pattern, while performing the primary task of interest. By tracking changes in secondary task performance (e.g., observing erratic finger tapping), we can track changes in processing resources being consumed by the primary task. This technique has been used in a wide variety of disciplines and situations. It has been used in advertising to study the effects of more or less suspenseful parts of a TV program on commercials (Owen et al., 1995) and in studying the effects of time-compressed audio commercials (Moore, Hausknecht, & Thamodaran, 1986). It has been used in sports to detect attention demands during horseshoe pitching (Prezuhy & Etnier, 2001) and rock climbing (Bourdin et al., 1998), while others have used it to study attention associated with posture control in patients who are older or suffering from brain disease (e.g., Maylor & Wing, 1996; Muller, Redfern, Furman, & Jennings, 2004). Murray, Holland, and Beason (1998) used a dual task study to detect the attention demands of speaking in people who suffer from aphasia after a stroke. Others have used the secondary task technique to study the attention demands of automobile driving (e.g., Baron & Kalsher, 1998), including the effects of distractions such as mobile telephones (Patten, Kircher, Ostlund, & Nilsson, 2004) and the potential of a fragrance to improve alertness (Schieber, Werner, & Larsen, 2000). Koukounas and McCabe (2001) and Koukounas and Over (1999) have used it to study the allocation of attention resources during sexual arousal. The notion of decreased secondary task performance due to a limited-capacity processing system is not simply a laboratory curiosity. Consider, for example, the crash of a Jetstream 3101 airplane as it was approaching for landing, killing all on board.
Conference papers on the topic "Pitching WEC"
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Heras, Pilar, Sarah Thomas, and Morten Kramer. "Validation of a Quasi-Linear Numerical Model of a Pitching Wave Energy Converter in Close Proximity to a Fixed Structure." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-61930.
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Although linear theory is often used to analyse wave energy devices, it is in many cases too simplistic. Many wave energy converters (WECs) exceed the key linear theory assumption of small amplitudes of motion, and require the inclusion of non-linear forces. A common approach is to use a hybrid frequency-time domain model based on the Cummins equation with hydro-dynamic inputs coming from linear wave theory (Ref. [1]). Published experimental data is sparse (Ref. [2]) and the suitability for the broad variety of WEC technologies has yet to be proven. This paper focuses on the challenges faced when attempting to validate a numerical model of a WEC using a variety of scaled physical tests in a waveflume. The technology used as a case study in this paper is a pitching WEC in close proximity to a fixed structure. Challenges are presented relating to waveflume effects and obtaining accurate physical input parameters to the numerical model.
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Umeda, Jun, Tomoki Taniguchi, and Toshifumi Fujiwara. "Study on a Wave Energy Converter With Tension Leg Mooring Under Optimal Control." In ASME 2019 38th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/omae2019-95650.
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Abstract A safety assessment for wave energy converters (WECs) in model scale is necessary before a demonstration test. WECs have various control conditions such as a maintenance and power generation mode etc. Although the safety assessment is required to carry out while considering the control conditions, the motion and load characteristics of the moored WEC to which applies various control conditions remains unclear. This study investigated the motion and load characteristics of the WEC including a mooring system when each control conditions was used. In experiments, the motion and load characteristics of the WEC without control were revealed. In the simulation, the motion and load characteristics were compared between two control methods which are the resistive loading control (RLC) and the approximate complex-conjugate control with considering the copper loss (ACL). The control methods have little effects on the surging, pitching and bending moment of the WEC. Mooring tension increased with increasing wave period when the RLC was used. When the ACL was applied, mooring tension reached the peak value near the natural period and decreased with increasing the wave period. The difference in the trends leads to that the control method maximizing mooring tension is not necessarily the same in each wave period. The select of the operating condition based on the wave period is required when the mooring tension of the WEC is assessed in the model-scale test stage.
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Husain, Salman, Jacob Davis, Nathan Tom, Krish Thiagarajan, Cole Burge, and Nhu Nguyen. "Influence on Structural Loading of a Wave Energy Converter by Controlling Variable-Geometry Components and the Power Take-Off." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-81518.
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Abstract Oceans are harsh environments and can impose significant loads on deployed structures. The deployment of wave energy converters (WECs) faces a design challenge with apparently contradictory goals. A WEC should be designed to maximize the energy absorbed while ensuring the operating wave condition does not exceed the failure limits of the device itself. Therefore, the loads endured by the support structure are a design constraint for the system. Adaptability to different sea states is, therefore, highly desirable. This work uses a WEC-Sim model of a variable-geometry oscillating wave energy converter (VGOSWEC) mounted on a support structure simulated under different wave scenarios. A VGOSWEC resembles a paddle pitching about a fixed hinge perpendicular to the incoming wave fronts. Therefore, the hinge experiences loads perpendicular to its axis as it maintains its position. The geometry of the VGOSWEC is varied by opening a series of controllable flaps on the pitching paddle when the structure experiences threshold loads. Because opening the flaps lets the waves transmit through the paddle, it is hypothesized that opening the flaps should result in load shedding at the base of the support structure. The load shedding is achieved by reducing the moments about the hinge axis. This work compares the hydrodynamic coefficients, natural periods, and response amplitude operators from completely closed to completely open configurations of the controllable flaps. The comparisons quantify the effects of letting the waves transmit through the VGOSWEC. This work shows that the completely open configuration can reduce the pitch and surge loads on the base of the support structure by as much as 80%. It was observed that at the paddle’s resonance frequency, the loads on the structure increased substantially. This increase in loads can be mitigated by a rotational power take-off damping about the hinge axis. Changing the rotational power take-off damping was identified as an additional design parameter that can be used to control the loads experienced by the WEC’s support structure.
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Giorcelli, Filippo, Sergej Antonello Sirigu, Edoardo Pasta, Daniele Giovanni Gioia, Mauro Bonfanti, and Giuliana Mattiazzo. "Wave Energy Converter Optimal Design Under Parameter Uncertainty." In ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-81464.
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Abstract In the field of renewable technologies, the possibility to obtain energy exploiting seas and oceans’ wave motion has been known for a long time. Devices that transform wave energy into electric energy exploiting wave motion are called Wave Energy Converters (WEC). Following the design studies carried out in recent years, the research now proceeds towards the development of useful processes for the optimization of these devices. In this work we develop a preliminary robust optimal design process for the WEC system devices, in order to increase their reliability and robustness. Robust optimal design is a probabilistic optimization method for realistic optimization problems, in which, the uncertainty that occurs between real-world implementations and their ideal project value is taken into account. This method studies these parameters and finds suitable solutions to avoid unsatisfactory system performances and designs which can compromise their performances. Therefore, the process final purpose is to obtain a robust optimum instead of a global optimum. In this work, we developed the robust design optimization strategy for the design of a pitching wave energy converter, able to minimize its Levelized Cost of Energy (LCoE). This is done exploiting information given by two selected robustness indexes.
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Babarit, Aure´lien, Jorgen Hals, Adi Kurniawan, Torgeir Moan, and Jorgen Krokstad. "Power Absorption Measures and Comparisons of Selected Wave Energy Converters." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49360.
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In this study, a selection of Wave Energy Converters (WECs) with different working principle is considered. It comprises a heaving device reacting against the seabed, a heaving self-reacting two-bodies device, a pitching device, and a floating OWC device. They are inspired by concepts which are currently under development. For each of these concepts, a numerical Wave To Wire (W2W) model is derived. Numerical estimates of the energy delivery which one can expect are derived using these numerical models on a selection of wave site along the European coast. This selection of wave site is thought to be representative with levels of mean annual wave power from 15 to 88 kW/m. Using these results, the performance of each WEC is assessed not only in terms of yearly energy output, but also in terms of yearly absorbed energy/displacement, yearly absorbed energy/wetted surface, and yearly absorbed energy per unit significant Power Take Off force. By comparing these criteria, one gets a better idea of the advantages and drawbacks of each of the studied concepts.
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Lucas, Jorge, Joa˜o Cruz, Stephen Salter, Jamie Taylor, and Ian Bryden. "Update on the Design of a 1:33 Scale Model of a Modified Edinburgh Duck WEC." In ASME 2008 27th International Conference on Offshore Mechanics and Arctic Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/omae2008-57230.
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A modified version of the Edinburgh Duck wave energy converter has been studied recently at the University of Edinburgh. From the design point of view the key innovation was a modification of the wetted profile. Wave energy is converted into useful work by the same pitching motion as in the original Duck, but by means of a circular cylinder with an off centred axis of rotation. This recent study was focused on a Duck version designed for vapour compression desalination rather than electricity production. An hydrodynamic numerical model (WAMIT) was used to predict first-order hydrodynamics quantities and to select and optimize configurations. The results obtained showed that it was possible, following the appropriate control strategies, to obtain similar energy absorption capabilities as the in the cam shaped original Duck. A 1:33 scale model was built to validate the numerical predictions. This paper extends the already published numerical predictions and experimental results obtained with this model. Experimental tests in random waves and measurements of the mooring forces for different submerged volumes will be reported for the first time.
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Afonja, Adetoso Justus, and Stefano Brizzolara. "Dynamic Response of a Wave Energy Converter With Resonant U-Tank." In ASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/omae2020-18553.
Full textAbstract:
Abstract This paper describes the concept design and preliminary dynamic analysis of a pitching wave energy converter (WEC) device, based on a pitching resonant floater, a pitch resonance tuning tank system and Wells turbines in regular head waves. The device has a bow/stern symmetry, which gives an advantage of the U-tank been strongly coupled with the floater in the pitch degree of freedom and both chambers will have their separate pneumatic turbines. The integrated dynamic model coupling the U-tank system as given with the motion of the floating body in regular waves and the power take off (PTO) device is physically and mathematically defined. This coupling effectively creates a multi-body dynamic system and thus alters the motion response amplitude operator of the device in waves creating multiple resonance peaks. The integrated dynamic model is solved in time domain to account for non-linearities. Excitation, radiation and diffraction forces are calculated in frequency domain from a 3D boundary element method (BEM) and corrected by Cummins equation (convolution integral) for memory effects to be used in the time domain solution. The time dependent motion of the free surface creates a pressure difference inside the chamber with respect to the atmosphere which is used by the PTO turbine. The dynamic model of the integrated system is used to predict the maximum extracted power for a given incident wave power. A systematic study, considering a change in PTO damping is performed to search for the maximum extracted power in any given regular wave condition.
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Huang, Zheng, Ying Xiong, Ye Xu, and Shancheng Li. "A Study on Fluid-Structure Interaction Performance of a Flexible Hydrofoil." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78522.
Full textAbstract:
To research the flexible hydrofoils’ hydroelastic response, the fluid-structure interaction (FSI) characteristic investigation is conducted on the basis of the analysis of a rigid hydrofoil’s hydrodynamic performance. For a rigid cantilevered rectangular hydrofoil, the pitching hydrodynamic performance is calculated using boundary motion with remeshing strategy. The Laminar Separation Bubble (LSB) and turbulent transition are captured. Numerical flow analysis revealed that the LSB occurs at 0.8c when pitching at initial angle of attack. As the angle increases to 5.1°, the laminar to turbulent transition occurs and the lift presents an inflection. For a geometric equivalent flexible hydrofoil, the static FSI characteristic is researched using oneway and two-way FSI method. The lift decreases and the drag increases using two-way compared to one-way FSI. The center of pressure and the maximum deformation move from trailing edge to leading edge as the angle of attack increases, showing the necessary of two-way FSI calculation. The transient FSI characteristic of the flexible hydrofoil is then studied using LES model. The lift fluctuation at 8° in frequency domain is calculated . The dry mode and wet mode natural frequency of the flexible hydrofoil are calculated to simulate the vibration performance, which meet the experiment data quite well, laying foundation for further research on the hydroelastic vibration response.
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Sim, Kyuho, and Daejong Kim. "Design and Hydrodynamic Performance of Hybrid Flexural Pivot Gas Bearings for High Speed Oil-Free Micro Turbomachinery." In World Tribology Congress III. ASMEDC, 2005. http://dx.doi.org/10.1115/wtc2005-63561.
Full textAbstract:
This paper introduces new flexural pivot tilting pad gas bearings for high speed oil-free micro turbomachinery. The new flexural pivot tilting pad gas bearings have a special web geometry that provides a radial stiffness to accommodate rotor growths and high vibrations at critical speed, a pitching stiffness to accommodate rotor-bearing misalignments or rotor bending vibrations, and a very small tilting stiffness for rotor stability. Comprehensive numerical simulations involving orbit simulations and coast-down simulations were performed to investigate the effects of preloads and pivot offsets on the critical speeds and onset speeds of instability. Higher preload and pivot offset increased both critical speeds of the rotor-bearing system and onset speeds of instability due to the increased wedge effect. Design procedures of radial stiffness were presented considering both rotor centrifugal and thermal growths. From simple adiabatic solution of temperature distribution of gas film under pure hydrodynamic mode, enough bearing clearance at pivot was found to be a very important design aspect for high speed hydrodynamic gas bearings. Asymmetric radial stiffness was chosen as a final design to meet the target design speed of 180 krpm for bearing diameter of 28.52mm. Suggested tilting pad gas bearing with asymmetric radial stiffness was predicted to be very stable even under high external destabilizing forces.
Reports on the topic "Pitching WEC"
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Fernandez, Ruben, Hernando Lugo, and Georfe Dulikravich. Aerodynamic Shape Multi-Objective Optimization for SAE Aero Design Competition Aircraft. Florida International University, October 2021. http://dx.doi.org/10.25148/mmeurs.009778.
Full textAbstract:
The SAE Regular Class Aero Design Competition requires students to design a radio-controlled aircraft with limits to the aircraft power consumption, take-off distance, and wingspan, while maximizing the amount of payload it can carry. As a result, the aircraft should be designed subject to these simultaneous and contradicting objectives: 1) minimize the aerodynamic drag force, 2) minimize the aerodynamic pitching moment, and 3) maximize the aerodynamic lift force. In this study, we optimized the geometric design variables of a biplane configuration using 3D aerodynamic analysis using the ANSYS Fluent. Coefficients of lift, drag, and pitching moment were determined from the completed 3D CFD simulations. Extracted coefficients were used in modeFRONTIER multi-objective optimization software to find a set of non-dominated (Pareto-optimal or best trade-off) optimized 3D aircraft shapes from which the winner was selected based to the desired plane performance.