Статті в журналах з теми "Motion response"
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1
Davis, M. R., N. L. Watson, and D. S. Holloway. "Measurement of Response Amplitude Operators for an 86 m High-Speed Catamaran." Journal of Ship Research 49, no. 02 (June 1, 2005): 121–43. http://dx.doi.org/10.5957/jsr.2005.49.2.121.
Повний текст джерелаАнотація:
Radar observations of encountered wave profile and measurements of vessel motions have been used to derive motion response amplitude operators, and the results are compared with predicted motion responses. Data were collected from an INCAT Tasmania built ferry while on delivery between Australia and England. It has been found that the predicted motions using a time domain method are consistent with those observed with respect to the increase of response with vessel speed and the decrease of response for seas encountered from the beam directions. Peak heave and pitch response amplitude operators were measured and computed at up to 2.5 and 1.8, respectively, at high speed in head seas. Conventional low-speed frequency domain motion analysis was found to give smaller predicted responses at somewhat higher frequency than the high-speed time-domain motion analysis. Significantly larger rolling motions were measured than predicted, and it appears that the action of the steering system may contribute substantially to in-service rolling.
2
Bermeitinger, Christina, Ryan Hackländer, Marie Kollek, Matthis Stiegemeyer, and Alexandra E. Tränkner. "Perceived and one’s own motion in response priming." Open Psychology 2, no. 1 (August 24, 2020): 213–37. http://dx.doi.org/10.1515/psych-2020-0106.
Повний текст джерелаАнотація:
AbstractIn response priming, motor pre-activations from a prime to the response to a target can be measured, as a function of whether they require the same (compatible) or different (incompatible) responses. With moving primes and static arrow targets, the results depend on the stimulus onset asynchrony between prime and target: with short SOAs, there were faster responses to compatible than incompatible targets, with longer SOAs, the pattern reverses. However, this reversal was not found with more biological motions. The current study comprised 3 experiments in order to replicate several findings from previous research and add evidence regarding the interplay of one’s own and perceived motions. Subjects performed a response priming task with moving prime stimuli while in motion themselves. With this paradigm, we tested the general influence of motion on responding and compatibility effects in response priming with moving prime stimuli. Furthermore, we assessed specific interactions of features of the perceived stimuli (e.g., moving vs. static; direction of the prime or target) and the own motion (e.g., walking vs. standing; direction of being rotated). We used two different own motions (walking on a treadmill, Exp. 1 & 3; rotating in a human gyroscope, Exp. 2) and two different visual stimulus types (rows-of-dots, Exp. 1 & 2; point light displays, Exp. 3). Compatibility effects were, in general, neither increased nor decreased during motion. Their size depended on the stimulus type, the velocity of one’s own motion, and several interactions of perceived and own motion. We discuss our findings with respect to perception-action interactions and previous findings on response priming with moving prime stimuli.
3
JACOB, C., K. SEPAHVAND, V. A. MATSAGAR, and S. MARBURG. "STOCHASTIC SEISMIC RESPONSE OF BASE-ISOLATED BUILDINGS." International Journal of Applied Mechanics 05, no. 01 (March 2013): 1350006. http://dx.doi.org/10.1142/s1758825113500063.
Повний текст джерелаАнотація:
The stochastic response of base-isolated building considering the uncertainty in the characteristics of the earthquakes is investigated. For this purpose, a probabilistic ground motion model, for generating artificial earthquakes is developed. The model is based upon a stochastic ground motion model which has separable amplitude and spectral non-stationarities. An extensive database of recorded earthquake ground motions is created. The set of parameters required by the stochastic ground motion model to depict a particular ground motion is evaluated for all the ground motions in the database. Probability distributions are created for all the parameters. Using Monte Carlo (MC) simulations, the set of parameters required by the stochastic ground motion model to simulate ground motions is obtained from the distributions and ground motions. Further, the bilinear model of the isolator described by its characteristic strength, post-yield stiffness and yield displacement is used, and the stochastic response is determined by using an ensemble of generated earthquakes. A parametric study is conducted for the various characteristics of the isolator. This study presents an approach for stochastic seismic response analysis of base-isolated building considering the uncertainty involved in the earthquake ground motion.
4
Kate Flint. "Response: Arrested Motion." Victorian Studies 60, no. 2 (2018): 201. http://dx.doi.org/10.2979/victorianstudies.60.2.05.
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5
Tian, Li, Hong Nan Li, and Wen Ming Wang. "Response of Transmission Lines under Three-Dimensional Seismic Excitations." Applied Mechanics and Materials 166-169 (May 2012): 2259–64. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.2259.
Повний текст джерелаАнотація:
The behavior of transmission line under three-dimensional seismic excitations is studied by numerical simulation. According to a practical engineering, the transmission towers are modeled by frame elements and the transmission lines are modeled by cable element account for the nonlinearity of the cable. The effects of single-dimensional, two-dimensional and three-dimensional ground motions on the responses of transmission line are investigated using nonlinear time history analysis method, respectively. The results indicate that the longitudinal maximum response of transmission lines can be obtained considering longitudinal ground motion excitation only. The transverse maximum response of transmission lines can be obtained considering transverse ground motion excitation only. Neglecting multiple nature of ground motion in analysis will significantly underestimate the vertical responses of the transmission lines. To obtain an accurate seismic response of transmission lines, three-dimensional ground motion inputs are required.
6
Streit, D. A., C. M. Krousgrill, and A. K. Bajaj. "Nonlinear Response of Flexible Robotic Manipulators Performing Repetitive Tasks." Journal of Dynamic Systems, Measurement, and Control 111, no. 3 (September 1, 1989): 470–79. http://dx.doi.org/10.1115/1.3153077.
Повний текст джерелаАнотація:
The dynamics of a flexible manipulator is described by two distinct types of variables, one describing the nominal motion and the other describing the compliant motion. For a manipulator programmed to perform repetitive tasks, the dynamical equations governing the compliant motion are parametrically excited. Nonlinear dynamics of a two-degree-of-freedom model is investigated in parameter regions where the nominal motion is predicted by the Floquet theory to be unstable. Multiple time scales technique is used to study the nonlinear response, and it is shown that the compliant coordinates can execute small but finite amplitude periodic motions. In one particular case, the amplitude of these periodic motions is shown to bifurcate to a periodic solution which subsequently undergoes period-doubling bifurcations leading to chaotic motions.
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Poulos, Alan, Eduardo Miranda, and Jack W. Baker. "Evaluation of Earthquake Response Spectra Directionality Using Stochastic Simulations." Bulletin of the Seismological Society of America 112, no. 1 (October 26, 2021): 307–15. http://dx.doi.org/10.1785/0120210101.
Повний текст джерелаАнотація:
ABSTRACT For earthquake-resistant design purposes, ground-motion intensity is usually characterized using response spectra. The amplitude of response spectral ordinates of horizontal components varies significantly with changes in orientation. This change in intensity with orientation is commonly known as ground-motion directionality. Although this directionality has been attributed to several factors, such as topographic irregularities, near-fault effects, and local geologic heterogeneities, the mechanism behind this phenomenon is still not well understood. This work studies the directionality characteristics of earthquake ground-motion intensity using synthetic ground motions and compares their directionality to that of recorded ground motions. The two principal components of horizontal acceleration are sampled independently using a stochastic model based on finite-duration time-modulated filtered Gaussian white-noise processes. By using the same stochastic process to sample both horizontal components of motion, the variance of horizontal ground acceleration has negligible orientation dependence. However, these simulations’ response spectral ordinates present directionality levels comparable to those found in real ground motions. It is shown that the directionality of the simulated ground motions changes for each realization of the stochastic process and is a consequence of the duration being finite. Simulated ground motions also present similar directionality trends to recorded earthquake ground motions, such as the increase of average directionality with increasing period of vibration and decrease with increasing significant duration. These results suggest that most of the orientation dependence of horizontal response spectra is primarily explained by the finite significant duration of earthquake ground motion causing inherent randomness in response spectra, rather than by some physical mechanism causing polarization of shaking.
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Su, Feng, John G. Anderson, and Yuehua Zeng. "Study of weak and strong ground motion including nonlinearity from the Northridge, California, earthquake sequence." Bulletin of the Seismological Society of America 88, no. 6 (December 1, 1998): 1411–25. http://dx.doi.org/10.1785/bssa0880061411.
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Abstract This article presents a new method to estimate S-wave site response relative to a regional layered crustal model. The method is useful for site-specific strong-motion prediction because the estimated site-response functions are referenced to an idealized regional layered model for which we know the ground response exactly. We applied this method to the Northridge earthquake sequence. We determined the site amplifications, from aftershocks with magnitudes 2.6 to 4.3, at 21 stations that were colocated with strong-motion stations. These site-response functions were then used to modify synthetic seismogram calculated for the Northridge mainshock in the same regional layered crustal model and thus obtain site-specific ground-motion estimates. These site-specific synthetic seismograms have higher correlation to observations in comparison to the synthetic seismograms without weak-motion site correction. They have similar amplitude and frequency content to the observations, especially at sites with recorded peak ground accelerations below 0.3 g. At sites with larger ground motions, however, this approach overestimates the strong motion. The differences are made clear when we estimate site-response functions from the strong-motion records and compare them with those from weak-motion records. We express the differences as the average ratio of the weak- to strong-motion site response (AWS ratio). When the ground motion is low, the AWS ratio is near unity, indicating that the weak- and strong-motion site responses agree with each other within the uncertainty. However, the AWS ratio increases as the ground-motion amplitude increses. The difference in weak- and strong-motion site responses becomes significant at stations where peak acceleration was above 0.3 g, peak velocity was above 20 cm/sec, or peak strain was above 0.06% during the mainshock. This result demonstrates directly from the ground-motion observations the relationship between nonlinear site response and peak ground-motion parameters. The nonlinearity is present on soft rock sites as well as on sediment sites.
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OKUYAMA, Takeshi, Kazuki HATAKEYAMA, and Mami TANAKA. "Frequency Response of Polymer Sensor for Measuring Finger Scratching Motion." Journal of the Japan Society of Applied Electromagnetics and Mechanics 23, no. 3 (2015): 618–23. http://dx.doi.org/10.14243/jsaem.23.618.
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Yuliastuti, Yuliastuti, Heri Syaeful, Arifan J. Syahbana, Euis E. Alhakim, and Tagor M. Sembiring. "ONE DIMENSIONAL SEISMIC RESPONSE ANALYSIS AT THE NON-COMMERCIAL NUCLEAR REACTOR SITE, SERPONG - INDONESIA." Rudarsko-geološko-naftni zbornik 36, no. 2 (2021): 1–10. http://dx.doi.org/10.17794/rgn.2021.2.1.
Повний текст джерелаАнотація:
One dimensional seismic response analysis on the ground surface of the Non-Commercial Power Reactor (RDNK) site based on the mean uniform hazard spectrum (UHS) and disaggregation analysis has been conducted. The study’s objective was to perform an analysis on site-specific response spectra on the ground surface based on existing mean UHS and disaggregation data of the site that correspond to a 1,000 and 10,000 year return period of earthquakes in compliance with the national nuclear regulatory body requirements of Indonesia. Detailed site characterization was defined based on secondary data of a geotechnical drill-hole, seismic cross-hole, downhole data, and microtremor array data. The dynamic site characteristic analysis was presented along with strong motion selection and processing using two types of strong motion datasets. An investigation of strong motion selection, spectral matching, and scaling has been presented as an essential step in ground motion processing. One-dimensional equivalent linear analysis simulation was performed by computing the processed ground motions. A seismic design spectrum and ground surface response spectra from the two datasets of strong motion, both corresponding to a 10,000 and 1,000 year return period, are presented at the end of this study. This study has shown that in order to establish the appropriate seismic response design spectrum, site-specific data and seismic hazard analysis must be immensely considered.
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Raudies, Florian, Ennio Mingolla, and Heiko Neumann. "A Model of Motion Transparency Processing with Local Center-Surround Interactions and Feedback." Neural Computation 23, no. 11 (November 2011): 2868–914. http://dx.doi.org/10.1162/neco_a_00193.
Повний текст джерелаАнотація:
Motion transparency occurs when multiple coherent motions are perceived in one spatial location. Imagine, for instance, looking out of the window of a bus on a bright day, where the world outside the window is passing by and movements of passengers inside the bus are reflected in the window. The overlay of both motions at the window leads to motion transparency, which is challenging to process. Noisy and ambiguous motion signals can be reduced using a competition mechanism for all encoded motions in one spatial location. Such a competition, however, leads to the suppression of multiple peak responses that encode different motions, as only the strongest response tends to survive. As a solution, we suggest a local center-surround competition for population-encoded motion directions and speeds. Similar motions are supported, and dissimilar ones are separated, by representing them as multiple activations, which occurs in the case of motion transparency. Psychophysical findings, such as motion attraction and repulsion for motion transparency displays, can be explained by this local competition. Besides this local competition mechanism, we show that feedback signals improve the processing of motion transparency. A discrimination task for transparent versus opaque motion is simulated, where motion transparency is generated by superimposing large field motion patterns of either varying size or varying coherence of motion. The model’s perceptual thresholds with and without feedback are calculated. We demonstrate that initially weak peak responses can be enhanced and stabilized through modulatory feedback signals from higher stages of processing.
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Lorteije, Jeannette A. M., J. Leon Kenemans, Tjeerd Jellema, Rob H. J. van der Lubbe, Frederiek de Heer, and Richard J. A. van Wezel. "Delayed Response to Animate Implied Motion in Human Motion Processing Areas." Journal of Cognitive Neuroscience 18, no. 2 (February 1, 2006): 158–68. http://dx.doi.org/10.1162/jocn.2006.18.2.158.
Повний текст джерелаАнотація:
Viewing static photographs of objects in motion evokes higher fMRI activation in the human medial temporal complex (MT+) than looking at similar photographs without this implied motion. As MT+ is traditionally thought to be involved in motion perception (and not in form perception), this finding suggests feedback from object-recognition areas onto MT+. To investigate this hypothesis, we recorded extracranial potentials evoked by the sight of photographs of biological agents with and without implied motion. The difference in potential between responses to pictures with and without implied motion was maximal between 260 and 400 msec after stimulus onset. Source analysis of this difference revealed one bilateral, symmetrical dipole pair in the occipital lobe. This area also showed a response to real motion, but approximately 100 msec earlier than the implied motion response. The longer latency of the implied motion response in comparison to the real motion response is consistent with a feedback projection onto MT+ following object recognition in higher-level temporal areas.
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Kim, Kyong-Hwan, Sewan Park, Jeong-Rok Kim, Il-Hyoung Cho, and Keyyong Hong. "Numerical and Experimental Analyses on Motion Responses on Heaving Point Absorbers Connected to Large Semi-Submersibles." Processes 9, no. 8 (August 3, 2021): 1363. http://dx.doi.org/10.3390/pr9081363.
Повний текст джерелаАнотація:
This study considers the motion responses of heaving point absorbers (HPAs) connected to large semi-submersibles. To analyze the motion responses for HPAs, a motion response amplitude operator (RAO) of a single HPA connected to a fixed wall was obtained in a two-dimensional wave flume. A frequency-domain eigenvalue analysis is used to evaluate the motion RAO of a single HPA, and the experimental and numerical results of motion RAO were compared. A model test was conducted to analyze the motions of multiple HPAs connected to a large semi-submersible in a 3D ocean basin. The motion RAOs of the multiple HPAs connected to the large semi-submersible were compared with the motion RAO of the single HPA connected to the fixed wall.
14
Zhang, Chang Hao, Wei Wang, Hu Wang, and Xun Tao Wang. "The Influence of near-Fault Ground Motions on the Seismic Response of Reinforced Concrete Frame." Applied Mechanics and Materials 90-93 (September 2011): 2633–39. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.2633.
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This paper examined the engineering characteristics of the near-fault ground motion. The four-story reinforced concrete frame was designed under Code for seismic design of building (GB50011-2010).The SAP2000 software was applied to model it, and the nonlinear time history analyses of structure were implemented. Near-fault ground motions with forward directivity and fling-step and far field ground motions were selected as seismic inputs．The results show that in terms of some structural dynamic response parameters, such as the vertex displacement, between the corner of the layer displacement, and the base shear et al., the structural responses to the ground motion with near-fault are increased by considerable magnitudes when the seismic responses of structures step into the elastic-plastic stage, compared with far-field ground motion, and the influence of damaging the mid-lower structure is significantly greater.
15
Lu, Xinzheng, Qingle Cheng, Yuan Tian, and Yuli Huang. "Regional Ground-Motion Simulation Using Recorded Ground Motions." Bulletin of the Seismological Society of America 111, no. 2 (January 12, 2021): 825–38. http://dx.doi.org/10.1785/0120200243.
Повний текст джерелаАнотація:
ABSTRACT Regional ground-motion simulation is important for postearthquake seismic damage assessment. Herein, a ground-motion simulation method using recorded ground motions is proposed. Inverse-distance-weighted interpolation of the response spectra is performed to obtain the response spectrum at the target location. Then the ground-motion time history for the target location is obtained by correcting the nearest-station records using the continuous wavelet transform. An evaluation measure for the accuracy of the predicted ground motion, that is, the response-spectrum error, is introduced, and its relationship with the seismic damage of regional buildings is determined via a city-scale nonlinear time-history analysis. The response-spectrum errors under different site conditions, distances, and elevation differences are analyzed. The application conditions for the proposed method are subsequently outlined. The Tsinghua campus is examined as a case study to validate the method. Finally, downtown San Francisco under an Mw 7.0 simulated earthquake on the Hayward fault is selected as an example to demonstrate the proposed method. The proposed method overcomes the difficulties in determining the intrastation ground motions and provides valuable input to postearthquake seismic damage assessment.
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Zhao, Guo Hui, Wen Hua Zhang, and Jian Hui Zhao. "Study on Seismic Response and Countermeasures of Long Span Cable-Stayed Bridge under Long Period Ground Motion." Applied Mechanics and Materials 71-78 (July 2011): 3841–44. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.3841.
Повний текст джерелаАнотація:
Long period ground motion has great influence on long period structures such as large oil tank, high-rise building and long span bridge. In this paper, a long span cable-stayed bridge is taken as an example to study the seismic response of long period structure under long period ground motions and conventional ground motions by using nonlinear dynamic time history method. It is shown that although the peak acceleration of the long period ground motions are no more than half of conventional ground motions, the displacement and force response of the bridge at key points under long period ground motions are much greater than that of conventional ground motions. Constraint cables and fluid viscous dampers are used to reduce in the influence of long period ground motion of the bridge, and the effects of the two countermeasures are also analyzed in this paper. The results show that constraint cables have unstable effect and even negative effect under long period ground motion. While fluid viscous dampers have stable effect under both long period ground motion and conventional ground motion with proper damping parameters.
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Lu, H., and A. Roe. "Response to motion and motion boundaries in monkey V2." Journal of Vision 7, no. 9 (March 23, 2010): 74. http://dx.doi.org/10.1167/7.9.74.
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Widhiada, I. Wayan, Endra Pitowarno, C. G. Indra Partha, and Yuda A. P. Wayan Reza. "Design and Simulation of Five Fingers Gripper for Dexterous Pick-Up Various of Components." Applied Mechanics and Materials 776 (July 2015): 325–30. http://dx.doi.org/10.4028/www.scientific.net/amm.776.325.
Повний текст джерелаАнотація:
In this paper, the authors describe and demonstrate how a Five fingered gripper can be designed and simulated to provide both gross motion and fine motion to the fingers. Satisfactory motion responses for the finger simulation are achieved. The fine motion including force feedback and the gross motions, which orientate the fingers into their approximate configuration is provided by an advance PID control strategy. The fingers are to be controlled in a manner which mimics the kinematics and dynamics of the five fingers of a human hand. This mimicry is required to design the correct motions necessary to handle engineering components. In order to evaluate the design philosophy and capability of the five fingered gripper, a challenging assembly process has been identified. The five fingered gripper assembly was built using Solidworks software tool, and it’s mechanical assembly representation was established in SimMechanics. The advance PID control is very effectively used to control the trajectory of the fingers. The simulation results have been demonstrated that the radius of finger movement is achieved in stable response. The signal error towards closed less than 1% which it indicates the response dynamic system response is stable.
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Dixit, Jagabandhu, D. M. Dewaikar, and R. S. Jangid. "Free Field Surface Motion at Different Site Types due to Near-Fault Ground Motions." ISRN Geophysics 2012 (July 29, 2012): 1–6. http://dx.doi.org/10.5402/2012/821051.
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Seismic hazards during many disastrous earthquakes are observed to be aggravating at the sites with the soft soil deposits due to amplification of ground motion. The characteristics of strong ground motion, the site category, depth of the soil column, type of rock strata, and the dynamic soil properties at a particular site significantly influence the free field motion during an earthquake. In this paper, free field surface motion is evaluated via seismic site response analysis that involves the propagation of earthquake ground motions from the bedrock through the overlying soil layers to the ground surface. These analyses are carried out for multiple near-fault seismic ground motions at 142 locations in Mumbai city categorized into different site classes. The free field surface motion is quantified in terms of amplification ratio, spectral relative velocity, and spectral acceleration. Seismic site coefficients at different time periods are also evaluated for each site category due to near-fault ground motions from the acceleration response spectra of free field surface motion at each site and the corresponding acceleration response spectra at a reference rock outcrop site.
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Ventura, Carlos E., W. D. Liam Finn, and Norman D. Schuster. "Seismic response of instrumented structures during the 1994 Northridge, California, earthquake." Canadian Journal of Civil Engineering 22, no. 2 (April 1, 1995): 316–37. http://dx.doi.org/10.1139/l95-045.
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This paper presents an overview of strong motion records obtained from instrumented structures during the 1994 Northridge earthquake. It describes the behaviour of buildings, bridges, and dams that have been instrumented by the major strong motion instrumentation networks operating in California and highlights important features of the most significant structural motions recorded during the earthquake. The structural damage observed during a reconnaissance visit to the affected areas by the earthquake is correlated with preliminary analyses of the recorded motions. Detailed discussions of the dynamic behaviour of two instrumented reinforced concrete buildings that suffered damage during the earthquake are presented. The behaviour of these buildings during previous earthquakes is also examined. This paper and the companion paper on ground motions provide comprehensive information about instrumental records obtained in the region affected by the earthquake. Key words: earthquake engineering, structural response, strong motion instrumentation, damage evaluation, buildings, bridges, dams, structural dynamics, acceleration, amplification.
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Murfet, Timothy, and Nagi Abdussamie. "Loads and Response of a Tension Leg Platform Wind Turbine with Non-Rotating Blades: An Experimental Study." Journal of Marine Science and Engineering 7, no. 3 (February 27, 2019): 56. http://dx.doi.org/10.3390/jmse7030056.
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This paper describes model testing of a Tension Leg Platform Wind Turbine (TLPWT) with non-rotating blades to better understand its motion and tendon responses when subjected to combined wind and unidirectional regular wave conditions. The TLPWT structure is closely based on the National Renewable Energy Laboratory (NREL) 5 MW concept. Multiple free decay tests were performed to evaluate the natural periods of the model in the key degrees of freedom, whilst Response Amplitude Operators (RAOs) were derived to show the motion and tendon characteristics. The natural periods in surge and pitch motions evaluated from the decay tests had a relatively close agreement to the theoretical values. Overall, the tested TLPWT model exhibited typical motion responses to that of a generalised TLP with significant surge offsets along with stiff heave and pitch motions. The maximum magnitudes for the RAOs of surge motion and all tendons occurred at the longest wave period of 1.23 s (~13.0 s at full-scale) tested in this study. From the attained results, there was evidence that static wind loading on the turbine structure had some impact on the motions and tendon response, particularly in the heave direction, with an average increase of 13.1% in motion amplitude for the tested wind conditions. The wind had a negligible effect on the surge motion and slightly decreased the tendon tensions in all tendons. The results also showed the set-down magnitudes amounting to approximately 2–5% of the offset. Furthermore, the waves are the dominant factor contributing to the set-down of the TLPWT, with a minimal contribution from the static wind loading. The results of this study could be used for calibrating numerical tools such as CFD codes.
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Utomo, Budi, and Muhammad Iqbal. "Vertical Motion Optimization of Series 60 Hull Forms Using Response Surface Methods." Kapal: Jurnal Ilmu Pengetahuan dan Teknologi Kelautan 17, no. 3 (October 29, 2020): 130–37. http://dx.doi.org/10.14710/kapal.v17i3.33212.
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There are many aspects to analyze seakeeping performance, one of which is the ship's vertical motion. As well-known, vertical motion and its derivatives, vertical velocity and acceleration, will be related to other aspects of seakeeping performance, such as slamming, deck wetness, and MSI. This study discusses optimizing the hull shape with small vertical motion using the Response Surface Methods (RSM). This research aims to minimize the ship's vertical motion so that the ship's performance is better than the initial one. Besides, this research was conducted to apply the RSM in the naval architecture field. The hull's shape used in this study is Series 60 hull form with a length of 31 m. The variables used for the optimization process are the ratio of L/B (X1) and B/T (X2) in the range of ± 10% with fixed displacement. Seakeeping analysis was carried out at a speed of 6.78 knots (Fr 0.2), a heading angle of 180°, and a significant wave height of 0.77 meters. The results show that the optimum model is found in Model 9 where the value of X1 = -2.94 or L/B = 6.71 and X2 = 5 or B/T = 2.75. Model 9 can reduce the vertical motion of the ship by 16.38%.
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Rodriguez-Marek, Adrian, Jennifer L. Williams, Joseph Wartman, and Pedro C. Repetto. "Ground Motion and Site Response." Earthquake Spectra 19, no. 1_suppl (January 2003): 11–34. http://dx.doi.org/10.1193/1.1737246.
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McDonald, J. Scott, Colin W. G. Clifford, Selina S. Solomon, Spencer C. Chen, and Samuel G. Solomon. "Integration and segregation of multiple motion signals by neurons in area MT of primate." Journal of Neurophysiology 111, no. 2 (January 15, 2014): 369–78. http://dx.doi.org/10.1152/jn.00254.2013.
Повний текст джерелаАнотація:
We used multielectrode arrays to measure the response of populations of neurons in primate middle temporal area to the transparent motion of two superimposed dot fields moving in different directions. The shape of the population response was well predicted by the sum of the responses to the constituent fields. However, the population response profile for transparent dot fields was similar to that for coherent plaid motion and hence an unreliable cue to transparency. We then used single-unit recording to characterize component and pattern cells from their response to drifting plaids. Unlike for plaids, component cells responded to the average direction of superimposed dot fields, whereas pattern cells could signal the constituent motions. This observation provides support for a strong prediction of the Simoncelli and Heeger (1998) model of motion analysis in area middle temporal, and suggests that pattern cells have a special status in the processing of superimposed dot fields.
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Priebe, Nicholas J., and Stephen G. Lisberger. "Constraints on the Source of Short-Term Motion Adaptation in Macaque Area MT. II. Tuning of Neural Circuit Mechanisms." Journal of Neurophysiology 88, no. 1 (July 1, 2002): 370–82. http://dx.doi.org/10.1152/jn.2002.88.1.370.
Повний текст джерелаАнотація:
Neurons in area MT, a motion-sensitive area of extrastriate cortex, respond to a step of target velocity with a transient-sustained firing pattern. The transition from a high initial firing rate to a lower sustained rate occurs over a time course of 20–80 ms and is considered a form of short-term adaptation. In the present paper, we compared the tuning of the adaptation to the neuron's tuning to direction and speed. The tuning of adaptation was measured with a condition/test paradigm in which a testing motion of the preferred direction and speed of the neuron under study was preceded by a conditioning motion: the direction and speed of the conditioning motion were varied systematically. The response to the test motion depended strongly on the direction of the conditioning motion. It was suppressed in almost all neurons by conditioning motion in the same direction and could be either suppressed or enhanced by conditioning motion in the opposite direction. Even in neurons that showed suppression for target motion in the nonpreferred direction, the adaptation and response direction tuning were the same. The speed tuning of adaptation was linked much less tightly to the speed tuning of the response of the neuron under study. For just more than 50% of neurons, the preferred speed of adaptation was more than 1 log unit different from the preferred response speed. Many neurons responded best when slow motions were followed by faster motions (acceleration) or vice versa (deceleration), suggesting that MT neurons may encode information about the change of target velocity over time. Finally, adaptation by conditioning motions of different directions, but not different speeds, altered the latency of the response to the test motion. The adaptation of latency recovered with shorter intervals between the conditioning and test motions than did the adaptation of response size, suggesting that latency and amplitude adaptation are mediated by separate mechanisms. Taken together with the companion paper, our data suggest that short-term motion adaptation in MT is a consequence of the neural circuit in MT and is not mediated by either input-specific mechanisms or intrinsic mechanisms related to the spiking of individual neurons. The circuit responsible for adaptation is tuned for both speed and direction and has the same direction tuning as the circuit responsible for the initial response of MT neurons.
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Cultrera, Giovanna, David M. Boore, William B. Joyner, and Christopher M. Dietel. "Nonlinear soil response in the vicinity of the Van Normal Complex following the 1994 Northridge, California, earthquake." Bulletin of the Seismological Society of America 89, no. 5 (October 1, 1999): 1214–31. http://dx.doi.org/10.1785/bssa0890051214.
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Abstract Ground-motion recording obtaineds at the Van Norman Complex from the 1994 Northridge, California, mainshock and its aftershocks constitute an excellent data set for the analysis of soil response as a function of ground-motion amplitude. We searched for nonlinear response by comparing the Fourier spectral ratios of two pairs of sites for ground motions of different levels, using data from permanent strong-motion recorders and from specially deployed portable instruments. We also compared the amplitude dependence of the observed ratios with the amplitude dependence of the theoretical ratios obtained from 1-D linear and 1-D equivalent-linear transfer functions, using recently published borehole velocity profiles at the sites to provide the low-strain material properties. One pair of sites was at the Jensen Filtration Plant (JFP); the other pair was the Rinaldi Receiving Station (RIN) and the Los Angeles Dam (LAD). Most of the analysis was concentrated on the motions at the Jensen sites. Portable seismometers were installed at the JFP to see if the motions inside the structures housing the strong-motion recorders differed from nearby free-field motions. We recorded seven small earthquakes and found that the high-frequency, low-amplitude motions in the administration building were about 0.3 of those outside the building. This means that the lack of high frequencies on the strong-motion recordings in the administration building relative to the generator building is not due solely to nonlinear soil effects. After taking into account the effects of the buildings, however, analysis of the suite of strong- and weak-motion recordings indicates that nonlinearity occurred at the JFP. As predicted by equivalent-linear analysis, the largest events (the mainshock and the 20 March 1994 aftershock) show a significant deamplification of the high-frequency motion relative to the weak motions from aftershocks occurring many months after the mainshock. The weak-motion aftershocks recorded within 12 hours of the mainshock, however, show a relative deamplification similar to that in the mainshock. The soil behavior may be a consequence of a pore pressure buildup during large-amplitude motion that was not dissipated until sometime later. The motions at (RIN) and (LAD) are from free-field sites. The comparison among spectral ratios of the mainshock, weak-motion coda waves of the mainshock, and an aftershock within ten minutes of the mainshock indicate that some nonlinearity occurred, presumably at (RIN) because it is the softer site. The spectral ratio for the mainshock is between that calculated for pure linear response and that calculated from the equivalent-linear method, using commonly used modulus reduction and damping ratio curves. In contrast to the Jensen sites, the ratio of motions soon after the high-amplitude portion of the mainshock differs from the ratio of the mainshock motions, indicating the mechanical properties of the soil returned to the low-strain values as the high-amplitude motion ended. This may indicate a type of nonlinear soil response different from that affecting motion at the Jensen administration building.
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Aquib, Tariq A., Jayalakshmi Sivasubramonian, and Paul M. Mai. "Analysis of Ground Motion Intensity Measures and Selection Techniques for Estimating Building Response." Applied Sciences 12, no. 23 (November 25, 2022): 12089. http://dx.doi.org/10.3390/app122312089.
Повний текст джерелаАнотація:
The structural response of buildings to earthquake shaking is of critical importance for seismic design purposes. Research on the relationship between earthquake ground motion intensity, building response, and seismic risk is ongoing, but not yet fully conclusive. Often, probability demand models rely on one ground motion intensity measure (IM) to predict the engineering demand parameter (EDP). The engineering community has suggested several IMs to account for different ground motion characteristics, but there is no single optimal IM. For this study, we compile a comprehensive list of IMs and their characteristics to assist engineers in making an informed decision. We discuss the ground motion selection process used for dynamic analysis of structural systems. For illustration, we compute building responses of 2D frames with different natural period subjected to more than 3500 recorded earthquake ground motions. Using our analysis, we examine the effects of different structural characteristics and seismological parameters on EDP-IM relationships by applying multi-regression models and statistical inter-model comparisons. As such, our results support and augment previous studies and suggest further improvements on the relationship between EDP and IM in terms of efficiency and sufficiency. Finally, we provide guidance on future approaches to the selection of both optimal intensity measures and ground motions using newer techniques.
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Tabeshpour, Mohammad Reza, and Reza Hedayatpour. "Analytical investigation of nonlinear heave-coupled response of tension leg platform." Proceedings of the Institution of Mechanical Engineers, Part M: Journal of Engineering for the Maritime Environment 233, no. 3 (June 7, 2018): 699–713. http://dx.doi.org/10.1177/1475090218776430.
Повний текст джерелаАнотація:
Having deep view in structural response of tension leg platform is important issue not only for response analysis but also for engineering design. Coupling between surge and heave motions of tension leg platform is such a problem. Here, tension leg platform motions are considered only in surge and heave degrees of freedom without pitch effect. The coupled term of heave is a nonlinear differential equation. Because the focus of this article is on this term, therefore, Duffing equation of motion in the surge direction is linearized. The wave forces are calculated using Airy’s wave theory and Morison’s equation, ignoring the diffraction effects. Current force also can be very important in dynamic analysis of tension leg platform. Because it affects the term of heave that is coupled with surge. It is shown that the effect of surge motion coupling on heave motion is very important in large displacement of surge motion in many sea states. The main result is that the coupling effects appeared in some frequencies such as heave and surge frequency, twice the frequency of wave, twice the natural surge frequency, and summation and difference of frequency of wave and surge frequency.
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Wu, Haitao, and Zhiyang Zhang. "Sensitivity Study of a Floating Production Storage and Offloading (FPSO) Motion Concerning Wave Parameters." Marine Technology Society Journal 55, no. 5 (September 1, 2021): 210–21. http://dx.doi.org/10.4031/mtsj.55.5.17.
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Abstract A floating production storage and offloading (FPSO) platform is an important facility for offshore oil and gas production. The purpose of this paper is to use a fully coupled time-domain analysis code to study the sensitivity of the FPSO motion to the wave parameters, which is significantly important for the safety and operability of the FPSO. First, the quality of the numerical model is tested by the difference between the near-field method and the far-field method. Then, a typical operational condition is used to analyze the motion responses of the FPSO. In this paper, the second-order low-frequency response of the surge motion is obtained by the Newman's approximation method. Finally, the influence of the significant wave height, the peak period, and the peak shape parameter on the surge, pitch, and heave motions of the FPSO is studied through the standard deviation (STD) and response spectrum. The response spectrum is obtained from the time history of the dynamic response through the fast Fourier transformation (FFT). The results of the dynamic coupled analysis reveal that the FPSO motion changes significantly under different wave parameters.
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Rasch, Malte J., Ming Chen, Si Wu, Haidong D. Lu, and Anna W. Roe. "Quantitative inference of population response properties across eccentricity from motion-induced maps in macaque V1." Journal of Neurophysiology 109, no. 5 (March 1, 2013): 1233–49. http://dx.doi.org/10.1152/jn.00673.2012.
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Interpreting population responses in the primary visual cortex (V1) remains a challenge especially with the advent of techniques measuring activations of large cortical areas simultaneously with high precision. For successful interpretation, a quantitatively precise model prediction is of great importance. In this study, we investigate how accurate a spatiotemporal filter (STF) model predicts average response profiles to coherently drifting random dot motion obtained by optical imaging of intrinsic signals in V1 of anesthetized macaques. We establish that orientation difference maps, obtained by subtracting orthogonal axis-of-motion, invert with increasing drift speeds, consistent with the motion streak effect. Consistent with perception, the speed at which the map inverts (the critical speed) depends on cortical eccentricity and systematically increases from foveal to parafoveal. We report that critical speeds and response maps to drifting motion are excellently reproduced by the STF model. Our study thus suggests that the STF model is quantitatively accurate enough to be used as a first model of choice for interpreting responses obtained with intrinsic imaging methods in V1. We show further that this good quantitative correspondence opens the possibility to infer otherwise not easily accessible population receptive field properties from responses to complex stimuli, such as drifting random dot motions.
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Cheng, Chuan, Chengpeng Wang, and Keming Cheng. "Response of an oblique shock train to downstream periodic pressure perturbations." Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 233, no. 1 (September 7, 2017): 57–70. http://dx.doi.org/10.1177/0954410017727028.
Повний текст джерелаАнотація:
An experimental investigation of the response of an oblique shock train to downstream periodic pressure perturbations was conducted. The oblique shock train is generated in a Mach 2.7 ducted flow and controlled by a downstream elliptical shaft. Cyclic rotating of the shaft leads to a periodic oscillatory motion of the oblique shock train. Six cases of perturbation frequency are studied. The results indicate that the downstream pressure perturbations propagate upstream to cause the oblique shock train to oscillate with a translational motion back and forth and the wall pressure to fluctuate with the same frequency. There is no distinct relative motion between the first oblique shock and the second shock during the motion process of the oblique shock train. The entire oblique shock train exhibits its behaviour of rigid motion and the strength of the first oblique shock of the oblique shock train is nearly stable during its periodic motion. There is a clear hysteresis effect in that the oblique shock train travels along a different path for the upstream and downstream motions. A simple analytical model was built based on these experimental data to analyse the oblique shock train dynamics.
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Mack, Arien, James Hill, and Steven Kahn. "Motion Aftereffects and Retinal Motion." Perception 18, no. 5 (October 1989): 649–55. http://dx.doi.org/10.1068/p180649.
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Two experiments are described in which it was investigated whether the adaptation on which motion aftereffects (MAEs) are based is a response to retinal image motion alone or to the motion signal derived from the process which combines the image motion signal with information about eye movement (corollary discharge). In both experiments observers either fixated a stationary point or tracked a vertically moving point while a pattern (in experiment 1, a grating; in experiment 2, a random-dot pattern) drifted horizontally across the field. In the tracking condition the adapting retinal motion was oblique. In the fixation condition it was horizontal. In every case in both conditions the MAE was horizontal, in the direction opposite to that of pattern motion. These results are consistent with the hypothesis that the adaptation is a response to the motion signal derived from the comparison of eye and image motion rather than to retinal motion per se. An alternative explanation is discussed.
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Wei, Wenhui, Aoxiong Dai, Yong-Lin Pi, and Mark Andrew Bradford. "Investigations on the Seismic Responses of Structures with a Suspended Mass." International Journal of Structural Stability and Dynamics 16, no. 02 (February 25, 2016): 1550066. http://dx.doi.org/10.1142/s0219455415500662.
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This paper presents the shaking table tests and an analytical study of structures with a suspended mass under coupled horizontal and tilting ground motions (CHT) caused by an earthquake. Shaking table tests of a 1:10 scaled model for a converter valve hall with a suspended mass in a high-voltage direct current electric power transmission station are carried out. The equations of motion for the structure, including the influence of the rotary inertia of the suspended mass, are derived. The responses of the model to different ground motions during an earthquake are investigated. It is found that the tilting ground motion plays a significant role in predicting the seismic response of the structure, and it needs to be considered in association with the horizontal ground motion. The response of the structure with a suspended mass to CHT ground motion is much larger than that to horizontal ground motion. The possibility of replacing the steel cables with springs as the suspending components is also investigated, and the spring is shown not to influence the acceleration and displacement responses greatly, but it significantly reduces the tension in the suspending components. Therefore, when a suspended mass is used as a mass-pendulum mitigation system, it is more advantageous to use springs or members having a low axial rigidity as the suspending components. In addition, the effects of the length of the cables and springs on the seismic response of the model with a suspended mass are also explored. It is found that the shorter the cables (or springs), the better the mitigation effects of the suspended mass on the main structure.
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Zhou, Jie, Linyun Xu, Yan Xuan, Yahui Xu, and Guanhua Liu. "Shedding Frequency and Motion of Jujube Fruits in Various Excitation Modes." Transactions of the ASABE 63, no. 4 (2020): 881–89. http://dx.doi.org/10.13031/trans.13776.
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HighlightsThe motion responses of fruits varied greatly in different excitation modes.The excitation modes included horizontal, vertical, and rotational.The shedding frequency of fruits was closely related to their motion response.The optimal excitation mode for Jun jujube is vertical excitation.Abstract. To study the shedding frequency and motion response of Chinese Jun jujube fruits with different excitation modes, a vibration device with three excitation modes (horizontal, vertical, and rotational) was designed. The mature fruits were categorized according to their degree of dryness (fresh, half-dried, and dried). The basic physical parameters (volume, density, pedical-fruit retention force, etc.), shedding frequency, and motion response of the fruits were measured. With horizontal excitation, the response of the fruits was mainly pendulum motion, which increased as the excitation amplitude increased, while the shedding frequency of the fruits correspondingly decreased. However, with vertical excitation, the response of the fruits was mainly a compound motion comprising pendulum and beam-column motions. As the excitation amplitude increased from 5 to 10 mm, the shedding frequency of the fruits decreased dramatically, but further decrease in the shedding frequency was negligible as the excitation amplitude increased to 15 mm. With rotational excitation, the fruits exhibited centrifugal rotation in an approximately horizontal plane, and the amplitude and frequency necessary to achieve dynamic separation were small. It was concluded that the optimal excitation mode for Jun jujube is vertical excitation with an amplitude of 10 mm and frequency between 6 and 10 Hz. Keywords: Excitation modes, Jujube, Motion gesture, Shedding frequency.
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Atkinson, Gail M., and David M. Boore. "Recent Trends in Ground Motion and Spectral Response Relations for North America." Earthquake Spectra 6, no. 1 (February 1990): 15–35. http://dx.doi.org/10.1193/1.1585556.
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Recent ground motion relations which predict pga, pgv and psrv for rock sites in ENA are based on a stochastic model whose parameters are indicated by seismological studies of earthquake source and attenuation processes. The validity of the model is verified by application to WNA. The choice of model parameters is validated by comparison of model predictions with ground motion data for ENA. For any magnitude, near-source ENA ground motions are enriched in high frequencies relative to WNA motions. This causes eastern pga values, and psrv values for frequencies greater than 10 Hz, to be greater than their western counterparts. For psrv at frequencies less than 10 Hz, median near-source ground motions in ENA are roughly comparable to those in WNA. Eastern ground motion characteristics have important implications for seismic hazard. High frequency structures in many parts of ENA face a hazard comparable to that in many active areas of California, whereas the hazard for low-frequency structures on rock sites in ENA is relatively modest.
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Tempa, Karma, Komal Raj Aryal, Nimesh Chettri, Giovanni Forte, and Dipendra Gautam. "Sensitivity analysis of input ground motion on surface motion parameters in high seismic regions: a case of Bhutan Himalaya." Natural Hazards and Earth System Sciences 22, no. 6 (June 7, 2022): 1893–909. http://dx.doi.org/10.5194/nhess-22-1893-2022.
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Abstract. Historical earthquakes demonstrate that strong motion characteristics and local soil condition, when coupled, significantly influence seismic site response. Interestingly, most of the Himalayan earthquakes depicted anomalous behavior per the site conditions historically. Being one of the most active seismic regions on earth, the eastern fringe of the Himalaya has observed many devastating earthquakes together with non-uniform damage scenarios. To quantify such anomalies, we evaluate surface motion parameters for a soft soil deposit located in the city of Phuentsholing in western Bhutan. Using one-dimensional site response analysis, the sensitivity of ground motion variation is estimated. This study accounts for the earthquakes of moment magnitudes 6.6 to 7.5 with a wide variation in peak ground acceleration (PGA). To dissect the characteristics of six inputted ground motions on eight local ground conditions, a sensitivity analysis is performed statistically. The statistical correlation of the response datasets and the linear regression model of the bedrock outcrop and the surface motion spectral acceleration along the stratified depth are examined to quantify the variation in surface motion parameters. The results highlight that the strong motions with PGA greater than 0.34 g demonstrate greater sensitivity, leading to some anomalies in response parameters, especially amplification. Similar results were obtained for the low PGA range (<0.1 g).
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Fontanella, Alessandro, Alan Facchinetti, Simone Di Carlo, and Marco Belloli. "Wind tunnel investigation of the aerodynamic response of two 15 MW floating wind turbines." Wind Energy Science 7, no. 4 (August 19, 2022): 1711–29. http://dx.doi.org/10.5194/wes-7-1711-2022.
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Abstract. The aerodynamics of floating turbines is complicated by large motions which are permitted by the floating foundation, and the interaction between turbine, wind, and wake is not yet fully understood. The object of this paper is a wind tunnel campaign finalized at characterizing the aerodynamic response of a 1:100 scale model of the IEA 15 MW subjected to imposed platform motion. The turbine aerodynamic response is studied focusing on thrust force, torque, and wake at 2.3D downwind the rotor. Harmonic motion is imposed in the surge, sway, roll, pitch, and yaw directions with several frequencies and amplitudes, which are selected to be representative of the two 15 MW floating turbines developed within the COREWIND project. Thrust and torque show large-amplitude oscillations with surge and pitch motion, the main effect of which is an apparent wind speed; oscillations in thrust and torque are negligible with the other motions, the main effect of which is to alter the wind direction. The thrust and torque response measured in the experiment is compared with predictions of a quasi-steady model, often used for control-related tasks. The agreement is good in the case of low-frequency surge motion, but some differences are seen in the pitch case. The quasi-steady model is not predictive for the response to wave-frequency motion, where blade unsteadiness may take place. Wake was measured imposing motion in five directions with frequency equal to the wave frequency. The axial speed is slightly lower with motion compared to the fixed case. The turbulence kinetic energy is slightly lower too. Wave-frequency motion seems to produce a more stable and lower flow mixing.
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Yu, Q., and H. P. Lee. "Influence of Cam Motions on the Dynamic Behavior of Return Springs." Journal of Mechanical Design 120, no. 2 (June 1, 1998): 305–10. http://dx.doi.org/10.1115/1.2826973.
Повний текст джерелаАнотація:
Based on the analytical solution of the equation of motion for a single degree-of-freedom model of a spring, the relation between the dynamic behavior and the kinematic features of input cam motions is discussed in this paper. A simple expression for the dynamic response spectrum of the vibration excited by the input motion is presented. It provides a useful tool to estimate the effect of cam motions on the dynamic behavior of springs. A method for the selection of cam motion curves based on this response spectrum is also presented in the paper. Examples are given to illustrate the method.
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Souto, David, and Dirk Kerzel. "Ocular tracking responses to background motion gated by feature-based attention." Journal of Neurophysiology 112, no. 5 (September 1, 2014): 1074–81. http://dx.doi.org/10.1152/jn.00810.2013.
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Involuntary ocular tracking responses to background motion offer a window on the dynamics of motion computations. In contrast to spatial attention, we know little about the role of feature-based attention in determining this ocular response. To probe feature-based effects of background motion on involuntary eye movements, we presented human observers with a balanced background perturbation. Two clouds of dots moved in opposite vertical directions while observers tracked a target moving in horizontal direction. Additionally, they had to discriminate a change in the direction of motion (±10° from vertical) of one of the clouds. A vertical ocular following response occurred in response to the motion of the attended cloud. When motion selection was based on motion direction and color of the dots, the peak velocity of the tracking response was 30% of the tracking response elicited in a single task with only one direction of background motion. In two other experiments, we tested the effect of the perturbation when motion selection was based on color, by having motion direction vary unpredictably, or on motion direction alone. Although the gain of pursuit in the horizontal direction was significantly reduced in all experiments, indicating a trade-off between perceptual and oculomotor tasks, ocular responses to perturbations were only observed when selection was based on both motion direction and color. It appears that selection by motion direction can only be effective for driving ocular tracking when the relevant elements can be segregated before motion onset.
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Klaycham, Karun, Chainarong Athisakul, and Somchai Chucheepsakul. "Nonlinear Response of Marine Riser with Large Displacement Excited by Top-End Vessel Motion using Penalty Method." International Journal of Structural Stability and Dynamics 20, no. 04 (March 24, 2020): 2050052. http://dx.doi.org/10.1142/s0219455420500522.
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A marine riser operated in a deep-water field could be substantially affected by large amounts of movement of the floating platform, which is more complicated and very challenging to analyze. This paper presents a mathematical model involving nonlinear dynamic response analysis of a marine riser caused by sways and heave motions at the top end, which are treated as the constraint conditions. The nonlinear equation of motion, arising from the nonlinearity of the ocean current and wave loadings, is derived and written in general matrix form using the finite element method. The excitation caused by platform movement is imposed on the riser system through the time-dependent constrained condition using the penalty method. The advantages of this method are that it is easily implemented on the nonlinear equation of motion and it requires no additional unknown variable, and thus consumes less computational time. By this method, the stiffness matrix and the force vector of the system are then modified, enforcing top-end vessel motion. The dynamic responses are evaluated by using numerical time integration based on Newmark’s method with direct iteration. The effects of the oscillation frequency of top-end vessel sway and heave motions on the nonlinear dynamic characteristics of the riser are investigated. The numerical results reveal that the riser responses to the top-end vessel excitation behave like a periodic motion, which is conformable to the characteristics of vessel movements. The increase in the oscillation frequency of the top-end vessel increases the maximum displacement amplitude for both the horizontal and vertical directions. The directional motion of the vessel also significantly influences the response amplitude of the riser.
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Haroun, Medhat A., and Essam A. Abdel-Hafiz. "Seismic response analysis of earth dams under differential ground motion." Bulletin of the Seismological Society of America 77, no. 5 (October 1, 1987): 1514–29. http://dx.doi.org/10.1785/bssa0770051514.
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Abstract The effects of amplitude and phase difference of an earthquake motion on the seismic response of long earth dams were studied. The dam was modeled as a two-dimensional shear beam whereas the seismic input, applied at the base of the dam, assumed various forms to reflect the variation of amplitude and phase of the ground motion. A computer program, based on the finite element method, was developed to compute the dam response to each of the assumed base motions. It was noted that the length-to-height ratio of the dam has a marked effect on the dynamic characteristics of the dam and on its seismic response. It was also found that the dam response can be sensitive to the assumed spatial variation of ground motion along its base.
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Zhang, B., and Z. Y. Chen. "General Winkler Model for Kinematic Responses of Shafts in Linear Soil." International Journal of Computational Methods 17, no. 05 (February 25, 2019): 1940004. http://dx.doi.org/10.1142/s0219876219400048.
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A simplified model for calculating the seismic responses of the shaft is proposed in this paper. Based on the theory of Winkler elastic foundation beam, the urban shaft is simplified as a vertical beam. The horizontal soil reaction and vertical shear tractions between the shaft circumference and the surrounding soils are considered through horizontal springs and rotating springs on the sidewall of the shaft. The translation and rocking motion of the shaft are considered through horizontal springs and rotating springs at the bottom of the shaft. Then, the dynamic analysis model of the shafts under seismic motion is established, and the control equation of the dynamic response of the shaft in frequency domain is deduced. The analytical solution of the steady state response of the shaft is obtained. Considering the randomness of the earthquake motion, this method can get the shaft kinematic responses under different ground motions efficiently in conceptual design process.
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Irmak, Tugrul, Ksander N. de Winkel, Daan M. Pool, Heinrich H. Bülthoff, and Riender Happee. "Individual motion perception parameters and motion sickness frequency sensitivity in fore-aft motion." Experimental Brain Research 239, no. 6 (March 29, 2021): 1727–45. http://dx.doi.org/10.1007/s00221-021-06093-w.
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AbstractPrevious literature suggests a relationship between individual characteristics of motion perception and the peak frequency of motion sickness sensitivity. Here, we used well-established paradigms to relate motion perception and motion sickness on an individual level. We recruited 23 participants to complete a two-part experiment. In the first part, we determined individual velocity storage time constants from perceived rotation in response to Earth Vertical Axis Rotation (EVAR) and subjective vertical time constants from perceived tilt in response to centrifugation. The cross-over frequency for resolution of the gravito-inertial ambiguity was derived from our data using the Multi Sensory Observer Model (MSOM). In the second part of the experiment, we determined individual motion sickness frequency responses. Participants were exposed to 30-minute sinusoidal fore-aft motions at frequencies of 0.15, 0.2, 0.3, 0.4 and 0.5 Hz, with a peak amplitude of 2 m/s2 in five separate sessions, approximately 1 week apart. Sickness responses were recorded using both the MIsery SCale (MISC) with 30 s intervals, and the Motion Sickness Assessment Questionnaire (MSAQ) at the end of the motion exposure. The average velocity storage and subjective vertical time constants were 17.2 s (STD = 6.8 s) and 9.2 s (STD = 7.17 s). The average cross-over frequency was 0.21 Hz (STD = 0.10 Hz). At the group level, there was no significant effect of frequency on motion sickness. However, considerable individual variability was observed in frequency sensitivities, with some participants being particularly sensitive to the lowest frequencies, whereas others were most sensitive to intermediate or higher frequencies. The frequency of peak sensitivity did not correlate with the velocity storage time constant (r = 0.32, p = 0.26) or the subjective vertical time constant (r = − 0.37, p = 0.29). Our prediction of a significant correlation between cross-over frequency and frequency sensitivity was not confirmed (r = 0.26, p = 0.44). However, we did observe a strong positive correlation between the subjective vertical time constant and general motion sickness sensitivity (r = 0.74, p = 0.0006). We conclude that frequency sensitivity is best considered a property unique to the individual. This has important consequences for existing models of motion sickness, which were fitted to group averaged sensitivities. The correlation between the subjective vertical time constant and motion sickness sensitivity supports the importance of verticality perception during exposure to translational sickness stimuli.
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de la Torre, Christopher A., Brendon A. Bradley, and Robin L. Lee. "Modeling nonlinear site effects in physics-based ground motion simulations of the 2010–2011 Canterbury earthquake sequence." Earthquake Spectra 36, no. 2 (March 30, 2020): 856–79. http://dx.doi.org/10.1177/8755293019891729.
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This study examines the performance of nonlinear total stress one-dimensional (1D) wave propagation site response analysis for modeling site effects in physics-based ground motion simulations of the 2010–2011 Canterbury, New Zealand earthquake sequence. This approach explicitly models three-dimensional (3D) ground motion phenomena at the regional scale, and detailed site effects at the local scale. The approach is compared with a more commonly used empirical VS30-based method of computing site amplification for simulated ground motions, as well as prediction via an empirical ground motion model. Site-specific ground response analysis is performed at 20 strong motion stations in Christchurch for 11 earthquakes with 4.7≤ MW≤7.1. When compared with the VS30-based approach, the wave propagation analysis reduces both overall model bias and uncertainty in site-to-site residuals at the fundamental period, and significantly reduces systematic residuals for soft or “atypical” sites that exhibit strong site amplification. The comparable performance in ground motion prediction between the physics-based simulation method and empirical ground motion models suggests the former is a viable approach for generating site-specific ground motions for geotechnical and structural response history analyses.
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Chen, Guan, Zhiren Zhu, and Jun Hu. "Simulation of response spectrum-compatible ground motions using wavelet-based multi-resolution analysis." Measurement and Control 54, no. 5-6 (May 2021): 641–46. http://dx.doi.org/10.1177/00202940211013057.
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This study proposed a simple and effective response spectrum-compatible ground motions simulation method to mitigate the scarcity of ground motions on seismic hazard analysis base on wavelet-based multi-resolution analysis. The feasibility of the proposed method is illustrated with two recorded ground motions in El Mayor-Cucapah earthquake. The results show that the proposed method enriches the ground motions exponentially. The simulated ground motions agree well with the attenuation characteristics of seismic ground motion without modulating process. Moreover, the pseudo-acceleration response spectrum error between the recorded ground motion and the average of the simulated ground motions is 5.2%, which fulfills the requirement prescribed in Eurocode 8 for artificially simulated ground motions. Besides, the cumulative power spectra between the simulated and recorded ground motions agree well on both high- and low-frequency regions. Therefore, the proposed method offers a feasible alternative in enriching response spectrum-compatible ground motions, especially on the regions with insufficient ground motions.
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Gao, Yue Wen, Chun Li, and Xin Cheng. "Performance Research on Tension Leg Platform of Floating Offshore Wind Turbine." Advanced Materials Research 724-725 (August 2013): 645–48. http://dx.doi.org/10.4028/www.scientific.net/amr.724-725.645.
Повний текст джерелаАнотація:
Platform structure is the basic guarantee for safety operation of offshore wind turbine. Based on the boundary element method and combined with multi-body dynamics, analyzing motion response and wave force mechanism to the platform structure, and obtained the dynamic response and the wave force change of the platform structures in time domain, last analyzes the motion response and wave force change of tension leg platform in surge, sway and heave also roll, pitch and yaw direction. The results show that the maximum response of sway and the minimum response of surge have the same direction, it is the same with the maximum response of pitch and the minimum response of roll ; Motion responses of heave and yaw change not as acutely as other four directions ; In time-domain variation range, motion response of surge, heave and pitch change acutely, while motion responses of sway, roll and yaw change slightly. Wave force focus mostly in heave and pitch direction. The results is high reference value on offshore tension leg platform structural design and optimization.
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FITRIADHY, AHMAD, and AMIRA ADAM. "CFD ANALYSIS ON VERTICAL MOTION OF A FULL-SCALE FLOATING JETTY." Journal of Sustainability Science and Management 15, no. 6 (August 30, 2020): 100–110. http://dx.doi.org/10.46754/jssm.2020.08.009.
Повний текст джерелаАнотація:
A floating jetty often experiences several vertical motions i.e., heave and pitch motion responses due to harsh environmental condition. This inherently makes discomfort to everyone during berthing on a floating; and even it potentially leads to loss of life due to falling down into the sea. A preliminary analysis using Computational Fluid Dynamics (CFD) simulation is necessary to be conducted to ensure user’s safety. The CFD analysis focused on the interaction between wave motions and the floating jetty and its effects on the vertical motions. The vertical motions of floating jetty were quantified by the Response Amplitude Operators (RAO). Several effects due to variation of wavelength (λ/L) have been studied. The CFD results revealed that the lower wavelength (λ/L<2.25) resulted in the increase of the heave and pitch motion amplitudes proportionally. However, the subsequent increase of wavelength (2.25>λ/L) has given results to less heave and pitch motion amplitudes. In general, it is shown that the vertical motion characteristics of the floating jetty predominantly depend on wave properties.
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Prucz, J. C., J. D’Acquisto, and J. E. Smith. "Dynamic Response of Composite Pressure Vessels to Inertia Loads." Journal of Pressure Vessel Technology 113, no. 1 (February 1, 1991): 86–91. http://dx.doi.org/10.1115/1.2928732.
Повний текст джерелаАнотація:
A new analytical model has been developed in order to investigate the potential benefits of using fiber-reinforced composites in pressure vessels that undergo rigid-body motions. The model consists of a quasi-static lamination analysis of a cylindrical, filament-wound, pressure vessel, combined with an elastodynamic analysis that accounts for the coupling effects between its rigid-body motion and its elastic deformations. The particular type of motion investigated in this paper is that of an oil-pressurized, tubular connecting rod in a slider-crank mechanism of an internal combustion engine. A comprehensive parametric study has been focused on the maximum wall stresses induced in such a rod by the combined effect of internal pressure and inertia loads associated with its motion. The numerical results illustrate potential ways to reduce these stresses by appropriate selection of material systems, lay-up configurations and geometric parameters.
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Firdaus, Nurman, Eko Budi Djatmiko, Rudi Walujo Prastianto, and Muryadin. "Experimental Study on Coupled Motion of Floating Crane Barge and Lifted Module in Irregular Waves." IOP Conference Series: Earth and Environmental Science 972, no. 1 (January 1, 2022): 012070. http://dx.doi.org/10.1088/1755-1315/972/1/012070.
Повний текст джерелаАнотація:
Abstract Installation and decommissioning activities of offshore structures often applied a floating crane barge for a lifting operation. The excessive movement response of lifted module affected by the motion of floating crane barge in waves can increase a large amplitude. However, the coupled motions of a floating crane barge and lifted module are not easy to predict accurately due to the dynamic movement of a lifted module and the complex coupling system. The coupled motion responses of a floating crane barge and a lifted module during lifting operation were investigated based on time domain by experimental method in this study. The model tests are carried out at Manoeuvring and Ocean Basin of Indonesian Hydrodynamic Laboratory, BRIN. The experimental conditions include the load cases of without and with a load of lifted module in crane tip, and the lifting operation was evaluated under irregular wave conditions. The experimental results show in that the phenomena of shift resonant frequency for the dynamic responses are clearly observed on the coupled motion of multibody system. The dynamic oscillations of the lifted module have a significant effect on the motion response of the floating crane barge. And the hoisting of lifted module has an obstructed effect on the rolling motion of crane barge.
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Yu, Chen Ping, William K. Page, Roger Gaborski, and Charles J. Duffy. "Receptive Field Dynamics Underlying MST Neuronal Optic Flow Selectivity." Journal of Neurophysiology 103, no. 5 (May 2010): 2794–807. http://dx.doi.org/10.1152/jn.01085.2009.
Повний текст джерелаАнотація:
Optic flow informs moving observers about their heading direction. Neurons in monkey medial superior temporal (MST) cortex show heading selective responses to optic flow and planar direction selective responses to patches of local motion. We recorded MST neuronal responses to a 90 × 90° optic flow display and to a 3 × 3 array of local motion patches covering the same area. Our goal was to test the hypothesis that the optic flow responses reflect the sum of the local motion responses. The local motion responses of each neuron were modeled as mixtures of Gaussians, combining the effects of two Gaussian response functions derived using a genetic algorithm, and then used to predict that neuron's optic flow responses. Some neurons showed good correspondence between local motion models and optic flow responses, others showed substantial differences. We used the genetic algorithm to modulate the relative strength of each local motion segment's responses to accommodate interactions between segments that might modulate their relative efficacy during co-activation by global patterns of optic flow. These gain modulated models showed uniformly better fits to the optic flow responses, suggesting that coactivation of receptive field segments alters neuronal response properties. We tested this hypothesis by simultaneously presenting local motion stimuli at two different sites. These two-segment stimuli revealed that interactions between response segments have direction and location specific effects that can account for aspects of optic flow selectivity. We conclude that MST's optic flow selectivity reflects dynamic interactions between spatially distributed local planar motion response mechanisms.