Journal articles on the topic 'Velocity plan'
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1
Liu, Yan Bin, Qing Hua Ji, Xiao Chao Sun, and Jian Hai Han. "Kinematics and Trajectory Tracking Motion Plan of an Unmanned Bicycle." Advanced Materials Research 152-153 (October 2010): 341–45. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.341.
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Kinematics and ground plane trajectory tracking motion plan of an unmanned bicycle were researched in this paper. For the unmanned bicycle controlled by a steering torque, a pedaling toque and a tilting torque, rigorous kinematics model was set up and discussed, and when the ground plane trajectories and the bicycle tilting angular trajectory were given, by use of Back-stepping design means, the steering angular velocity, the rear wheel rotation angular velocity and the other motion parameters trajectories of the unmanned bicycle were planned and discussed, the simulation results showed that the kinematics model built was accurate and rigorous, all above motion parameter plans were reasonable.
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Sciutti, Alessandra, Laurent Demougeot, Bastien Berret, Simone Toma, Giulio Sandini, Charalambos Papaxanthis, and Thierry Pozzo. "Visual gravity influences arm movement planning." Journal of Neurophysiology 107, no. 12 (June 15, 2012): 3433–45. http://dx.doi.org/10.1152/jn.00420.2011.
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When submitted to a visuomotor rotation, subjects show rapid adaptation of visually guided arm reaching movements, indicated by a progressive reduction in reaching errors. In this study, we wanted to make a step forward by investigating to what extent this adaptation also implies changes into the motor plan. Up to now, classical visuomotor rotation paradigms have been performed on the horizontal plane, where the reaching motor plan in general requires the same kinematics (i.e., straight path and symmetric velocity profile). To overcome this limitation, we considered vertical and horizontal movement directions requiring specific velocity profiles. This way, a change in the motor plan due to the visuomotor conflict would be measurable in terms of a modification in the velocity profile of the reaching movement. Ten subjects performed horizontal and vertical reaching movements while observing a rotated visual feedback of their motion. We found that adaptation to a visuomotor rotation produces a significant change in the motor plan, i.e., changes to the symmetry of velocity profiles. This suggests that the central nervous system takes into account the visual information to plan a future motion, even if this causes the adoption of nonoptimal motor plans in terms of energy consumption. However, the influence of vision on arm movement planning is not fixed, but rather changes as a function of the visual orientation of the movement. Indeed, a clear influence on motion planning can be observed only when the movement is visually presented as oriented along the vertical direction. Thus vision contributes differently to the planning of arm pointing movements depending on motion orientation in space.
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Asfour, Omar S. "EFFECT OF BUILDING PLAN FORM ON HUMAN THERMAL COMFORT IN NATURALLY VENTILATED OPEN-PLAN ENCLOSURES LOCATED IN HOT CLIMATES." Journal of Green Building 12, no. 2 (March 2017): 112–29. http://dx.doi.org/10.3992/1943-4618.12.2.112.
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This study aims to examine the effect of building plan form on internal thermal comfort conditions in naturally ventilated open-plan buildings located in hot climates. The study examined the square and the rectangular plan forms in relation to several values of wind direction, building plan depth, and climatic conditions. The study utilised CFD for ventilation prediction, DesignBuilder for thermal modelling, and the Tropical Summer Index (TSI) for thermal comfort assessment. These three tools were integrated in a quantitative approach to fulfil the study aim. The study concluded that the use of area-weighted average velocity magnitude is more accurate in the assessment of natural ventilation performance, as it accounts for both internal velocity magnitude and distribution. The study confirmed the common observation that the use of shallow building plans is more effective to increase internal air velocity and improve internal thermal comfort. At some point of increased plan depth, the internal air velocity magnitude dramatically decreases. In the three examined wind directions, this occurred when the plan depth exceeded 3H in the square cases and 2.5H in the rectangular ones, where H is the building height. This value is much less than the commonly recommended maximum value of 5H. The study also concluded that reducing building depth in the square cases has generally more potential to improve thermal comfort conditions when compared with the rectangular cases. The gross increase in Percentage of People Comfortable, PPC, in all the examined cases was 23% in the square cases, compared to 11% in the rectangular cases.
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Socco, Laura Valentina, Cesare Comina, and Farbod Khosro Anjom. "Time-average velocity estimation through surface-wave analysis: Part 1 — S-wave velocity." GEOPHYSICS 82, no. 3 (May 1, 2017): U49—U59. http://dx.doi.org/10.1190/geo2016-0367.1.
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In some areas, the estimation of static corrections for land seismic data is a critical step of the processing workflow. It often requires the execution of additional surveys and data analyses. Surface waves (SWs) in seismic records can be processed to extract local dispersion curves (DCs) that can be used to estimate near-surface S-wave velocity models. Here we focus on the direct estimation of time-average S-wave velocity models from SW DCs without the need to invert the data. Time-average velocity directly provides the value of one-way time, given a datum plan depth. The method requires the knowledge of one 1D S-wave velocity model along the seismic line, together with the relevant DC, to estimate a relationship between SW wavelength and investigation depth on the time-average velocity model. This wavelength/depth relationship is then used to estimate all the other time-average S-wave velocity models along the line directly from the DCs by means of a data transformation. This approach removes the need for extensive data inversion and provides a simple method suitable for industrial workflows. We tested the method on synthetic and field data and found that it is possible to retrieve the time-average velocity models with uncertainties less than 10% in sites with laterally varying velocities. The error on one-way times at various depths of the datum plan retrieved by the time-average velocity models is mostly less than 5 ms for synthetic and field data.
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Jiang, Zhanyuan, Jianquan Ge, Qiangqiang Xu, and Tao Yang. "Terminal Impact Time Control Cooperative Guidance Law for UAVs under Time-Varying Velocity." Drones 5, no. 3 (September 17, 2021): 100. http://dx.doi.org/10.3390/drones5030100.
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Aiming at the problem that multiple Unmanned Aerial Vehicles (UAVs) attack the stationary target cooperatively under time-varying velocity, the cooperative guidance law with finite time convergence on two-dimensional plan and the three-dimensional cooperative guidance laws with impact time constraint are designed separately in this paper. Firstly, based on the relative motion equation between UAV and target on two-dimensional plane, the time cooperative guidance model of multiple UAVs is established. Then based on the consistency theory and graph theory, a distributed time cooperative guidance law is designed, which can ensure that the impact time of all UAVs can be quickly consistent in a limited time. Next, the cooperative guidance problem is expanded from two-dimensional plane to three-dimensional space, the motion model between UAV and target in three-dimensional space is established and the expression of time-to-go estimation under time-varying velocity is derived. Finally, according to whether there is the communication among UAVs under the condition of time-varying velocity, a multiple UAVs three-dimensional cooperative guidance law based on desired impact time and a multiple UAVs three-dimensional cooperative guidance law based on coordination variables are designed, respectively. The simulation results show that the cooperative guidance law with finite time convergence on two-dimensional plan and the three-dimensional cooperative guidance law with impact time constraint proposed in this paper are effective, which can both realize the saturation attack under the time-varying velocity.
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Gopal, Atul, Sumitash Jana, and Aditya Murthy. "Contrasting speed-accuracy tradeoffs for eye and hand movements reveal the optimal nature of saccade kinematics." Journal of Neurophysiology 118, no. 3 (September 1, 2017): 1664–76. http://dx.doi.org/10.1152/jn.00329.2017.
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In contrast to hand movements, the existence of a neural representation of saccade kinematics is unclear. Saccade kinematics is typically thought to be specified by motor error/desired displacement and generated by brain stem circuits that are not penetrable to voluntary control. We studied the influence of instructed hand movement velocity on the kinematics of saccades executed without explicit instructions. When the hand movement was slow the saccade velocity decreased, independent of saccade amplitude. We leveraged this modulation of saccade velocity to study the optimality of saccades (in terms of velocity and endpoint accuracy) in relation to the well-known speed-accuracy tradeoff that governs voluntary movements (Fitts’ law). In contrast to hand movements that obeyed Fitts' law, normometric saccades exhibited the greatest endpoint accuracy and lower reaction times, relative to saccades accompanying slow and fast hand movements. In the slow condition, where saccade endpoint accuracy suffered, we observed that targets were more likely to be foveated by two saccades resulting in step-saccades. Interestingly, the endpoint accuracy was higher in two-saccade trials, compared with one-saccade trials in both the slow and fast conditions. This indicates that step-saccades are a part of the kinematic plan for optimal control of endpoint accuracy. Taken together, these findings suggest normometric saccades are already optimized to maximize endpoint accuracy and the modulation of saccade velocity by hand velocity is likely to reflect the sharing of kinematic plans between the two effectors. NEW & NOTEWORTHY The optimality of saccade kinematics has been suggested by modeling studies but experimental evidence is lacking. However, we observed that, when subjects voluntarily modulated their hand velocity, the velocity of saccades accompanying these hand movements was also modulated, suggesting a shared kinematic plan for eye and hand movements. We leveraged this modulation to show that saccades had less endpoint accuracy when their velocity decreased, illustrating that normometric saccades have optimal speed and accuracy.
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Acakpovi, Amevi, Majeed B. Issah, Francois X. Fifatin, and Mathias B. Michael. "Wind velocity extrapolation in Ghana by Weibull probability density function." Wind Engineering 42, no. 1 (August 10, 2017): 38–50. http://dx.doi.org/10.1177/0309524x17723205.
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This article proposes a database of reliable wind velocities across the whole Ghana divided into 24 locations, based on data collected for the year 2013, although the bigger plan is to cover the period 2013–2018. For the year 2013 specifically, the proposed data were obtained through extrapolation of RETScreen data on wind velocity in Ghana, originally taken at a height of 10 m to a height of 60 m, adequate for generation using Weibull distribution function. The model led to the determination of the shape factor k and the scale factor c for all the 24 locations which subsequently led to the extrapolated wind velocity. The lowest and highest wind speeds were recorded, respectively, as 3.77 and 8.24 m/s for Wenchi and Wa locations in Ghana. The utmost relevance of this article is of national dimension to Ghana as the resulting wind velocities may be useful to undertake feasibility studies or real implementation of wind power plant.
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Wang, Dong Qing, En Rong Mao, and Xiu Jie Yin. "Research on Deviation Correction Control Technique of the Paver’s Traveling System." Advanced Materials Research 490-495 (March 2012): 1777–82. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.1777.
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In order to improve the performance of crawler paver’s traveling and reduce the paver’s straight traveling deviation, a new control plan of paver’s traveling system was proposed. In the control plan, the left wheel control method adopted velocity closed loop control in order to keep constant-speed moving of the paver. The right wheel control method adopted the series structure of fuzzy control and PID control in which the fuzzy controller slightly adjusted the right wheel set point of PID controller according to the distance difference variable and velocity difference variable of paver’s left wheel and right wheel. In the working condition of straight paving, the real time deviation correction is achieved to assure paver’s straight traveling.
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Ferreira, Elise, Morgan Dal, Christophe Colin, Guillaume Marion, Cyril Gorny, Damien Courapied, Jason Guy, and Patrice Peyre. "Experimental and Numerical Analysis of Gas/Powder Flow for Different LMD Nozzles." Metals 10, no. 5 (May 20, 2020): 667. http://dx.doi.org/10.3390/met10050667.
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The Laser Metal Deposition (LMD) process is an additive manufacturing method, which generates 3D structures through the interaction of a laser beam and a gas/powder stream. The stream diameter, surface density and focal plan position affect the size, efficiency and regularity of the deposit tracks. Therefore, a precise knowledge of the gas/powder streams characteristics is essential to control the process and improve its reliability and reproducibly for industrial applications. This paper proposes multiple experimental techniques, such as gas pressure measurement, optical and weighting methods, to analyze the gas and particle velocity, the powder stream diameter, its focal plan position and density. This was carried out for three nozzle designs and multiple gas and powder flow rates conditions. The results reveal that (1) the particle stream follows a Gaussian distribution while the gas velocity field is closer to a top hat one; (2) axial, carrier and shaping gas flow significantly impact the powder stream’s focal plan position; (3) only shaping gas, powder flow rates and nozzle design impact the powder stream diameter. 2D axisymmetric models of the gas and powder streams with RANS turbulent model are then performed on each of the three nozzles and highlight good agreements with experimental results but an over-estimation of the gas velocity by pressure measurements.
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Wang, Rui, Changchun Liang, Dong Pan, Xiaodong Zhang, Pengfei Xin, and Xiaodong Du. "Research on a Visual Servo Method of a Manipulator Based on Velocity Feedforward." Space: Science & Technology 2021 (September 10, 2021): 1–8. http://dx.doi.org/10.34133/2021/9763179.
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In this paper, a method of predicting the motion state of a moving target in the base coordinate system by hand-eye vision and the position and attitude of the end is proposed. The predicted value is used as the velocity feedforward, and the position-based visual servo method is used to plan the velocity of the end of the manipulator. It overcomes the influence of end coordinate system motion on target prediction in a discrete system and introduces an integral control method to compensate for the prediction velocity, eliminating the end tracking error caused by target velocity prediction error. The effectiveness of this method is verified by simulation and experiment.
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Bieleke, Kriech, and Wolff. "Served Well? A Pilot Field Study on the Effects of Conveying Self-control Strategies on Volleyball Service Performance." Behavioral Sciences 9, no. 9 (September 2, 2019): 93. http://dx.doi.org/10.3390/bs9090093.
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Volleyball serves constitute an important example for a self-controlled sequence of actions in sports that is difficult to improve. It is therefore paramount to investigate whether and how conveying self-control strategies to athletes affects their service performance. To address this question, we conducted a pilot field study with sixty-two players from four Swiss volleyball schools. They performed a warm-up and subsequently a first series of 15 serves. Objective service performance was measured in terms of errors, velocity, and precision. Afterwards, players formulated either individual goals (goal condition) or plans (plan condition) based on their coaches' correction instructions. In a second series of 15 serves objective performance was worse in some respects compared to the first series (i.e., more errors in the plan condition, reduced precision in both conditions). Mixed-effects analyses of performance development across conditions in the second series showed initially reduced but steadily recouping precision and velocity, while the number of errors stayed constant. In contrast to the objective performance, coaches evaluated their players' service performance during the second series of serves as substantially better than during the first series. Taken together, the results of this pilot field study suggest that conveying either goals or plans as self-control strategies may involve initial adjustment costs followed by a subsequent recovery period.
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Valentina Socco, Laura, and Cesare Comina. "Time-average velocity estimation through surface-wave analysis: Part 2 — P-wave velocity." GEOPHYSICS 82, no. 3 (May 1, 2017): U61—U73. http://dx.doi.org/10.1190/geo2016-0368.1.
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Surface waves (SWs) in seismic records can be used to extract local dispersion curves (DCs) along a seismic line. These curves can be used to estimate near-surface S-wave velocity models. If the velocity models are used to compute S-wave static corrections, the required information consists of S-wave time-average velocities that define the one-way time for a given datum plan depth. However, given the wider use of P-wave reflection seismic with respect to S-wave surveys, the estimate of P-wave time-average velocity would be more useful. We therefore focus on the possibility of also extracting time-average P-wave velocity models from SW dispersion data. We start from a known 1D S-wave velocity model along the line, with its relevant DC, and we estimate a wavelength/depth relationship for SWs. We found that this relationship is sensitive to Poisson’s ratio, and we develop a simple method for estimating an “apparent” Poisson’s ratio profile, defined as the Poisson’s ratio value that relates the time-average S-wave velocity to the time-average P-wave velocity. Hence, we transform the time-average S-wave velocity models estimated from the DCs into the time-average P-wave velocity models along the seismic line. We tested the method on synthetic and field data and found that it is possible to retrieve time-average P-wave velocity models with uncertainties mostly less than 10% in laterally varying sites and one-way traveltime for P-waves with less than 5 ms uncertainty with respect to P-wave tomography data. To our knowledge, this is the first method for reliable estimation of P-wave velocity from SW data without any a priori information or additional data.
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Yang, Fan, Yiqi Zhang, Chao Liu, Tieli Wang, Dongjin Jiang, and Yan Jin. "Numerical and Experimental Investigations of Flow Pattern and Anti-Vortex Measures of Forebay in a Multi-Unit Pumping Station." Water 13, no. 7 (March 29, 2021): 935. http://dx.doi.org/10.3390/w13070935.
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The forebay of a pumping station is an important building connecting the diversion channel and the intake pool. Based on the physical model test and research method of computational fluid dynamics (CFD) based on the improved fluid volume model, the flow field in a forebay of a multi-unit pumping station is analyzed in combination with the engineering practice of the Exi River flood discharge station in the Anhui Province, China. Aiming at the technical problems of a large-scale swing water area in the forebay internal flow field of a lateral intake pumping station, the technical problems are discussed. Different rectification measures are selected to adjust the flow pattern in the forebay of a pumping station. The internal rectification flow pattern in the forebay under different plans, the uniformity of flow velocity distribution in the measurement section, and the reduction rate of the vortex area are studied and compared, and the optimal plan is given. The results show that the flow pattern of the 7.5 m and 15 m solutions of the lengthened inflow wall is still poor, and the ability to eliminate vortices is not strong or even counterproductive. The combination plan of a rectifier sill and a rectifier pier has a better effect and can eliminate more than 90% of the vortex, but the uniformity of flow speed has not been significantly improved at the inlet of the pumping station; the combination plan of a rectifier sill and a diversion wall opening has the best effect; the reduction rate of the vortex area is more than 85%, and the velocity uniformity of three measuring sections is better than that of the original plan. The uniformity of flow rate near the pumping station is increased by 4% and that far away from the pumping station is increased by 13%. The combination plan of a rectifier sill and diversion wall with openings is recommended.
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Miller, Matthew A., Sandra E. Yuter, Nicole P. Hoban, Laura M. Tomkins, and Brian A. Colle. "Detecting wave features in Doppler radial velocity radar observations." Atmospheric Measurement Techniques 15, no. 6 (March 22, 2022): 1689–702. http://dx.doi.org/10.5194/amt-15-1689-2022.
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Abstract. Mesoscale, wave-like perturbations in horizontal air motions in the troposphere (velocity waves) are associated with vertical velocity, temperature, and pressure perturbations that can initiate or enhance precipitation within clouds. The ability to detect velocity waves from horizontal wind information is an important tool for atmospheric research and weather forecasting. This paper presents a method to routinely detect velocity waves using Doppler radial velocity data from a scanning weather radar. The method utilizes the difference field between consecutive position plan indicator (PPI) scans at a given elevation angle. Using the difference between fields a few minutes apart highlights small-scale perturbations associated with waves because the larger-scale wind field changes more slowly. Image filtering retains larger contiguous velocity bands and discards noise. Wave detection scales are limited by the size of the temporal difference relative to the wave motion and the radar resolution volume size.
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Diffee, G. M., V. J. Caiozzo, R. E. Herrick, and K. M. Baldwin. "Contractile and biochemical properties of rat soleus and plantaris after hindlimb suspension." American Journal of Physiology-Cell Physiology 260, no. 3 (March 1, 1991): C528—C534. http://dx.doi.org/10.1152/ajpcell.1991.260.3.c528.
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This study examined the relationship between contractile and isomyosin changes occurring in rat soleus (SOL) and plantaris (PLAN) muscles after 28 days of hindlimb suspension. SOL muscles from suspended animals exhibited a 45% decline in muscle weight compared with controls (P less than 0.05) accompanied by a 49% decrease in peak twitch tension (Pt) and a 59% reduction in peak tetanic tension (Po). Smaller reductions were observed in muscle weight, Pt, and Po (12, 43, and 24%, respectively) for the suspended PLAN. Maximal shortening velocity (Vmax) of the suspended SOL and the velocity of unloaded shortening were increased by 36 and 35%, respectively, but there was no suspension-induced change in PLAN Vmax. Suspension induced a 22% increase in SOL myosin adenosinetriphosphatase (ATPase) activity that was accompanied by a shift in the native myosin isoform distribution characterized by an increase in the relative amounts of intermediate and fast myosin. The more modest changes in the contractile function of suspended PLAN were accompanied by a small (7%) increase in myosin ATPase activity but no significant changes in myosin isoform distribution. The results of this study confirm that hindlimb suspension results in significant speeding of SOL contractile properties and suggest that the shift toward faster myosin isoforms with a higher myosin ATPase activity likely accounts for these mechanical changes.
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Tan, Sirui, Gboyega Ayeni, Jaewoo Park, Mehdi Aharchaou, Peter Traynin, William Burnett, Anatoly Baumstein, et al. "Integrated velocity and attenuation model building: Sakhalin case study." Leading Edge 41, no. 3 (March 2022): 197–203. http://dx.doi.org/10.1190/tle41030197.1.
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Shallow gas accumulations with varied spatial distribution and scales cause amplitude loss and phase distortion in seismic images in underlying reservoir intervals. We present an integrated velocity and attenuation (defined by the quality factor Q) model-building workflow to address the imaging challenges in a shallow-water data set acquired offshore Sakhalin Island, Russia. As part of the workflow, we use full-waveform inversion (FWI) to capture fine details of the velocity and Q models. We achieve a step change in image quality improvement and amplitude fidelity enhancement by leveraging the workflow. This image enhancement improves subsurface interpretation and influences well placement, subsurface model building, and depletion plan optimization. Key to this success is not only the advanced model-building tool kit, which includes FWI and tomography, but also the optimal integration of the tools specifically tailored for the geologic setting and imaging challenges offshore Sakhalin Island.
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Sheng, Jian, Yu Meng Wang, Han Lv, and Qing Fu Yang. "Velocity Calculation of Lahar in Changbai Mountain Region." Advanced Materials Research 726-731 (August 2013): 829–32. http://dx.doi.org/10.4028/www.scientific.net/amr.726-731.829.
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Lahar as one of most serious volcanic hazards, threats peoples lives and property securities of volcanic region. Velocity is the most important parameter for lahar hazard assessment and prevention. The calculation result of lahar velocity can provide reference materials for making hazard prevention plan, and make the hazard relief measure of lahar transition from passive to active. Selected the area near the Tianchi as the research region, and divided the research region into forming region, circulation region and accumulation region. In order to establish the calculation model, divided the circulation region and accumulation region into many meshes, which were small enough to meet the calculation accuracy. The calculation time step length was also identified very small as 0.001 min. Calculated the average and peak velocity of lahar, triggered by the assuming medium and small eruption of Tianchi volcano. The longitudinal variation of lahar frontal average and peak velocity was acquired by the numerical simulation result. Although there is some different between the assumption of this research and the actual condition, flow velocity and accumulation situation of lahar are calculated in quantity and extension by numerical simulation, these result has reference value for preventing and reducing lahar disaster.
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Tambe, Nilesh S., Isabel M. Pires, Craig Moore, Andrew Wieczorek, Sunil Upadhyay, and Andrew W. Beavis. "Predicting personalised and progressive adaptive dose escalation to gross tumour volume using knowledge-based planning models for inoperable advanced-stage non-small cell lung cancer patients treated with volumetric modulated arc therapy." Biomedical Physics & Engineering Express 8, no. 3 (March 4, 2022): 035001. http://dx.doi.org/10.1088/2057-1976/ac56eb.
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Abstract Objectives. Increased radiation doses could improve local control and overall survival of lung cancer patients, however, this could be challenging without exceeding organs at risk (OAR) dose constraints, especially for patients with advanced-stage disease. Increasing OAR doses could reduce the therapeutic ratio and quality of life. It is therefore important to investigate methods to increase the dose to target volume without exceeding OAR dose constraints. Methods. Gross tumour volume (GTV) was contoured on synthetic computerised tomography (sCT) datasets produced using the Velocity adaptive radiotherapy software for eleven patients. The fractions where GTV volume decreased compared to that prior to radiotherapy (reference plan) were considered for personalised progressive dose escalation. The dose to the adapted GTV (GTVAdaptive) was increased until OAR doses were affected (as compared to the original clinical plan). Planning target volume (PTV) coverage was maintained for all plans. Doses were also escalated to the reference plan (GTVClinical) using the same method. Adapted, dose-escalated, plans were combined to estimate accumulated dose, D99 (dose to 99%) of GTVAdapted, PTV D99 and OAR doses and compared with those in the original clinical plans. Knowledge-based planning (KBP) model was developed to predict D99 of the adapted GTV with OAR doses and PTV coverage kept similar to the original clinical plans; prediction accuracy and model verification were performed using further data sets. Results. Compared to the original clinical plan, the dose to GTV was significantly increased without exceeding OAR doses. Adaptive dose-escalation increased the average D99 to GTVAdaptive by 15.1Gy and 8.7Gy compared to the clinical plans. The KBP models were verified and demonstrated prediction accuracy of 0.4% and 0.7% respectively. Conclusion. Progressive adaptive dose escalation can significantly increase the dose to GTV without increasing OAR doses or compromising the dose to microscopic disease. This may increase overall survival without increasing toxicities.
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Birzhandi, Mohammad S., and Amir M. Halabian. "Probabilistic assessment of plan-asymmetric structures under the near-fault pulse-like events considering soil–structure interaction." Advances in Structural Engineering 22, no. 3 (September 7, 2018): 702–21. http://dx.doi.org/10.1177/1369433218798305.
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This study aims to evaluate the torsional effects and soil–structure interaction simultaneously under near-fault pulse-like earthquakes in a probabilistic framework. Incremental dynamic analysis and fragility curves are employed for this goal. An eight-story R/C dual lateral load-resistant building consisting of shear walls and moment resisting frames is used. The median incremental dynamic analysis curves reported the maximum capacity for the symmetric structure in each foundation conditions. In addition, the capacity of structure will be increased when more shear wave velocity is assumed. Therefore, from this view, neglecting the soil–structure interaction will not be in the safe side. Fragility curves (using intensity measure directly) show that for different cases (except for very low shear wave velocity), more value of eccentricity leads to more probability of collapse. Moreover, the fragility curves show that (for each eccentricity), soil–structure interaction effect is significant only for the flexible base structure with the very low shear wave velocity (100 m/s) and more eccentricity value leads to less soil–structure interaction effects. Results show that the significant eccentricity value may lead to reduce the soil–structure interaction effect in the shear-wall structures under the near-fault events.
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Wang, Lan, Lingjie Lin, Ying Chang, and Da Song. "Velocity Planning for Astronaut Virtual Training Robot with High-Order Dynamic Constraints." Robotica 38, no. 12 (February 10, 2020): 2121–37. http://dx.doi.org/10.1017/s0263574719001863.
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SUMMARYIn order to improve the training efficiency and establish a multi-person cooperative training simulation system, including “virtual human,” in the process of virtual reality-based astronaut training, it is necessary to plan the velocity at which astronauts carry the target object. A velocity planning algorithm, combining a traditional six-stage acceleration/deceleration algorithm, based on a time-discrete model with high-order dynamic constraints, considering the elastic damping torque of the space suit, is proposed. The described algorithm is verified on MATLAB to prove its feasibility. Compared to other algorithms, the planning time of the proposed algorithm is significantly reduced.
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Chen, Yan, Ken Chen, Hua Yan, Li Qiang Wang, and Lin Bin Zheng. "Simulation Analysis of Coating at Uniform Velocity of Robotic Spray Gun." Applied Mechanics and Materials 246-247 (December 2012): 1175–80. http://dx.doi.org/10.4028/www.scientific.net/amm.246-247.1175.
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Coating uniformity model was developed to optimize spray painting robot trajectories, assuming uniform robot motion and a parabolic spray distribution with uniformity evaluated based on the thickness variation. Dimensionless calculation results show that overlapping distance is a major influencing factor of mean coating thickness, and that seed path position and work piece width are secondary ones. Overlapping distance is a critical influencing factor of coating uniformity, but seed path position and work piece width exert little influence on coating uniformity. Minimum thickness variance is about 0.0025 if overlapping distance is between 0.29 and 0.31. Thus, Overlapping distance should be taken into account to plan robot trajectory for spray painting, but seed path position and work piece width could be neglected.
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Eden, D. J., T. J. T. Moore, M. J. Currie, A. J. Rigby, E. Rosolowsky, Y. Su, Kee-Tae Kim, et al. "CHIMPS2: survey description and 12CO emission in the Galactic Centre." Monthly Notices of the Royal Astronomical Society 498, no. 4 (September 10, 2020): 5936–51. http://dx.doi.org/10.1093/mnras/staa2734.
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ABSTRACT The latest generation of Galactic Plane surveys is enhancing our ability to study the effects of galactic environment upon the process of star formation. We present the first data from CO Heterodyne Inner Milky Way Plane Survey 2 (CHIMPS2). CHIMPS2 is a survey that will observe the Inner Galaxy, the Central Molecular Zone (CMZ), and a section of the Outer Galaxy in 12CO, 13CO, and C18O $(J = 3\rightarrow 2)$ emission with the Heterodyne Array Receiver Program on the James Clerk Maxwell Telescope (JCMT). The first CHIMPS2 data presented here are a first look towards the CMZ in 12CO J = 3 → 2 and cover ${-}3^{\circ }\, \le \, \ell \, \le \, 5^{\circ }$ and $\mid {b} \mid \, \le \, 0{_{.}^{\circ}} 5$ with angular resolution of 15 arcsec, velocity resolution of 1 km s−1, and rms $\Delta \, T_A ^\ast =$ 0.58 K at these resolutions. Such high-resolution observations of the CMZ will be a valuable data set for future studies, whilst complementing the existing Galactic Plane surveys, such as SEDIGISM, the ${Herschel}$ infrared Galactic Plane Survey, and ATLASGAL. In this paper, we discuss the survey plan, the current observations and data, as well as presenting position–position maps of the region. The position–velocity maps detect foreground spiral arms in both absorption and emission.
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Orlando, Luciana. "Multidisciplinary Approach to a Recovery Plan of Historical Buildings." International Journal of Geophysics 2011 (2011): 1–12. http://dx.doi.org/10.1155/2011/258043.
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The paper emphasizes the advantages of employing multiple data techniques—geology, GPS, surveys of cracking, boreholes, seismic refraction and electrical resistivity tomography—to image the shallow stratigraphy and hypothesize the cause of instability of an urban area. The study is focused on the joint interpretation of the crack pattern, topographic monitoring and the features of the underground, to define the area affected by instability and the direction of ground motion with the objective to advance a hypothesis on the cause of the instability of the area and to depict the main features. Borehole stratigraphies for a univocal interpretation of the lithology of electrical and seismic data and electrical resistivity tomography to constrain the interpretation of the lateral velocity variations and thickness of seismic bedrock were used. The geophysical surveys reveals to be complementary in the depicting of underground features. The study is approached at small and medium scale.
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Yang, Lu Jiang, De Wen Liu, Zhong Li Guo, Jing Li, and Bi Hui Dai. "Engineering Mechanics in High-Rise Building with Irregular Planner." Applied Mechanics and Materials 540 (April 2014): 193–96. http://dx.doi.org/10.4028/www.scientific.net/amm.540.193.
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Plane functional layout and total controlling plan of the general plan in the building always are abnormal. Furthermore the floor size and horizontal stiffness in the same floor are different tremendously, otherwise there are many dislocation floor in the same floor, according to different function in the same floor. Irregular plane in the building may happen according to the situation above. It is harmful to the force,, displacement and deformation in irregular plane. In order to research the essence of the irregular plane and avoid it, firstly the irregular plane is introduced, also we have distinguished stretch joint, settlement joint and, seismic joint according to the force theory of structure, and then we have used PKPM structural calculation program to build model, simulating the force in two improved models on the dead load, live load and horizontal seismic load, we have gotten the maximum displacement, maximum displacement angle, velocity, acceleration, shear force and moment, then we have analysised and compared displacement, movement and force. Finally, we have concluded:“Architectural design should be adopted by regular plane designing rule，it should not be adopted by irregular plane designing rule；for the building structure which body is complex and irregular plane，the designer should install the seismic joint in the appropriate parts according to actual needs，make the irregular building structure into several regular unit structure which could resist the horizontal load.”
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Wang, Yan, and Hui Lin Yao. "Application of GRNN to Plan Trajectory for a Picking Robot." Advanced Materials Research 468-471 (February 2012): 194–99. http://dx.doi.org/10.4028/www.scientific.net/amr.468-471.194.
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In order to supply reference inputs for the robot system, a high-order polynomial function is proposed according to particular strategies to plan trajectory in joint space, which could provide continuous velocity, acceleration and jerk to ensure safety for electric actuators and stability of the robot during the motion process. The general regression neural network (GRNN) is constructed to realize the proposed polynomial function for its powerful non-linear mapping ability. Parameters of the spreading factor and number of training samples which influence the performances of the network are detailed analyzed. Simulation results show that GRNN has advantages of favorable stability and high precision of function approaching even with few samples. Finally, the trajectory planner based on GRNN is successfully applied for an articulated picking robot to realize the real-time control.
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Poletto, Flavio, José M. Carcione, Massimo Lovo, and Francesco Miranda. "Acoustic velocity of seismic‐while‐drilling (SWD) borehole guided waves." GEOPHYSICS 67, no. 3 (May 2002): 921–27. http://dx.doi.org/10.1190/1.1484534.
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Borehole guided waves, other than the extensional waves traveling through the drillstring, can be used as pilot signals to obtain seismic‐while‐drilling (SWD) seismograms and information about the drilling conditions. This occurs when there is no rotation of the drillstring while drilling and when the contacts between the drillpipe and the borehole wall preclude the propagation of the extensional wave. To obtain the velocity of the guided waves, we model the compressional‐wave velocity of drilling mud with different compositions of low‐ and high‐gravity solids, corresponding to a given drilling plan and taking into account the presence of formation cuttings and in‐situ conditions. Then we compute the velocities of the tube wave (with and without casing) and the guided wave traveling in the mud inside the drillstring (pipe wave). The results indicate the pipe wave constitutes a reliable pilot signal in the absence of drillpipe rotation. This allows us to obtain a complete depth reverse vertical seismic profile.
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Xia, Guoqing, Zhiwei Han, Bo Zhao, and Xinwei Wang. "Local Path Planning for Unmanned Surface Vehicle Collision Avoidance Based on Modified Quantum Particle Swarm Optimization." Complexity 2020 (April 13, 2020): 1–15. http://dx.doi.org/10.1155/2020/3095426.
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An unmanned surface vehicle (USV) plans its global path before the mission starts. When dynamic obstacles appear during sailing, the planned global path must be adjusted locally to avoid collision. This study proposes a local path planning algorithm based on the velocity obstacle (VO) method and modified quantum particle swarm optimization (MQPSO) for USV collision avoidance. The collision avoidance model based on VO not only considers the velocity and course of the USV but also handles the variable velocity and course of an obstacle. According to the collision avoidance model, the USV needs to adjust its velocity and course simultaneously to avoid collision. Due to the kinematic constraints of the USV, the velocity window and course window of the USV are determined by the dynamic window approach (DWA). In summary, local path planning is transformed into a multiobjective optimization problem with multiple constraints in a continuous search space. The optimization problem is to obtain the USV’s optimal velocity variation and course variation to avoid collision and minimize its energy consumption under the rules of the International Regulations for Preventing Collisions at Sea (COLREGs) and the kinematic constraints of the USV. Since USV local path planning is completed in a short time, it is essential that the optimization algorithm can quickly obtain the optimal value. MQPSO is primarily proposed to meet that requirement. In MQPSO, the efficiency of quantum encoding in quantum computing and the optimization ability of representing the motion states of the particles with wave functions to cover the whole feasible solution space are combined. Simulation results show that the proposed algorithm can obtain the optimal values of the benchmark functions and effectively plan a collision-free path for a USV.
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Li, Yuting, Zhiyao Song, Guoqiang Peng, Xuwen Fang, Ruijie Li, Peng Chen, and Haoyuan Hong. "Modeling Hydro-Dynamics in a Harbor Area in the Daishan Island, China." Water 11, no. 2 (January 23, 2019): 192. http://dx.doi.org/10.3390/w11020192.
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This study presents an incorporation and application of a two-dimensional, unstructured-grid hydrodynamic model with a suspended sediment transport module in Daishan, China. The model is verified with field measurement data from 2017: water level, flow velocities and suspended sediment concentration (SSC). In the application on the Daishan, the performance of the hydrodynamic model has been satisfactorily validated against observed variations of available measurement stations. Coupled with the hydrodynamic model, a sediment transport model has been developed and tested. The simulations agreed quantitatively with the observations. The validated model was applied to the construction of breakwaters and docks under a different plan. The model can calculate the flow field and siltation situation under different breakwater settings. After we have analyzed the impact of existing breakwater layout schemes and sediment transport, a reasonable plan will be selected. The results show that the sea area near the north of Yanwo Shan and Dongken Shan has a large flow velocity exceeding 2.0 m/s and the flow velocity within the isobath of 5 m is small, within 0.6 m/s. According to the sediment calculation, the dock project is feasible. However, the designed width of the fairway should be increased to ensure the navigation safety of the ship according to variation characteristics of cross flow velocity in channel.
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Rocha, Helena, Ugo Lafont, and João P. Nunes. "Optimisation of Through-Thickness Embedding Location of Fibre Bragg Grating Sensor in CFRP for Impact Damage Detection." Polymers 13, no. 18 (September 12, 2021): 3078. http://dx.doi.org/10.3390/polym13183078.
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Aerospace composites are susceptible to barely visible impact damage (BVID) produced by low-velocity-impact (LVI) events. Fibre Bragg grating (FBG) sensors can detect BVID, but often FBG sensors are embedded in the mid-plan, where residual strains produced by impact damage are lower, leading to an undervaluation of the damage severity. This study compares the residual strains produced by LVI events measured by FBG embedded at the mid-plan and other through-thickness locations of carbon fibre reinforced polymer (CFRP) composites. The instrumented laminates were subjected to multiple low-velocity impacts while the FBG signals were acquired. The FBG sensor measurements allowed not only for the residual strain after damage to be measured, but also for a strain peak at the time of impact to be detected, which is an important feature to identify the nature and presence of BVID in real-life applications. The results allowed an adequate optical fibre (OF) embedding location to be selected for BVID detection. The effect of small- and large-diameter OF on the impact resistance of the CFRP was compared.
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Wendt, Anke S., Monzurul Alam, and Joao Paulo Castagnoli. "Sand injectite mapping using a resistivity-velocity transform function." Leading Edge 40, no. 3 (March 2021): 202–7. http://dx.doi.org/10.1190/tle40030202.1.
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Lack of resolution in the distribution of sand injectites in hydrocarbon fields is common and makes it difficult to predict drilling challenges and plan for optimum production. A practical workflow was developed that enables the distinction of shale and sand bodies by using a combination of low-resolution seismic data and high-resolution resistivity log data. Measured resistivity logs were used to predict synthetic velocity logs, which accurately match shale velocities and over- or underestimate velocities of other rock types. The synthetic velocity logs were spatially distributed in a 3D cube in order to predict synthetic velocities in between and away from the well locations. The 3D cube was representative of a field. It covered the interval from the seabed to below the reservoir. The spatial distribution was based on a geostatistical approach guided by measured seismic interval velocities. A residual velocity cube was calculated from the measured and synthetic velocities. The residual velocity cube produced near-zero velocities for shaly materials and velocity over- or underestimates for other rock types. Interpretation of the residual velocity cube required the identification of strong stratigraphic markers. The markers were removed from the residual cube by setting their specific layer velocities to 0 m/s. The final information stored in the residual velocity cube was then related to the over- or underestimated velocities in sand bodies.
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Marjiyono, Marjiyono, Hadi Suntoko, A. Soehaimi, Yuliastuti Yuliastuti, and H. Syaeful. "KELAS SOIL DAERAH SEKITAR RENCANA TAPAK REAKTOR DAYA EKSPERIMENTAL (RDE) SERPONG DARI DATA MIKROTREMOR." Jurnal Pengembangan Energi Nuklir 17, no. 1 (June 15, 2015): 57. http://dx.doi.org/10.17146/jpen.2015.17.1.2591.
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ABSTRAK KELAS SOIL DAERAH SEKITAR RENCANA TAPAK REAKTOR DAYA EKSPERIMENTAL (RDE) SERPONG DARI DATA MIKROTREMOR. Karakteristik geologi permukaan memegang peranan penting dalam analisis respon gelombang di suatu wilayah. Sehubungan dengan rencana pembangunan Reaktor Daya Eksperimental (RDE) di Serpong, telah dilakukan pemodelan kondisi bawah permukaan dari kombinasi data mikrotremor array dan single station. Pengukuran mikrotremor array dilakukan di 9 lokasi, sedangkan single station di 90 lokasi yang tersebar pada radius ± 1 km di sekitar tapak RDE. Model bawah permukaan yang berupa struktur kecepatan gelombang geser selanjutnya dijadikan dasar untuk menghitung nilai Vs30 di daerah tersebut. Hasil klasifikasi soil berdasarkan nilai Vs30 menunjukkan kelas soil untuk wilayah sekitar tapak RDE secara umum terdiri atas kelas SD (soil menengah) dan SC (batuan lunak). Lokasi rencana tapak sendiri berada dalam wilayah kelas soil SD. Kata kunci : kelas soil, kecepatan gelombang geser, mikrotremor, tapak RDE, Vs30. ABSTRACT SOIL CLASS AROUND THE SERPONG EXPERIMENTAL POWER REACTOR (EPR) SITE PLAN BASE ON MICROTREMOR DATA. Surface geological characteristics has an important role on site response analysis in a region. In regard with experimental power reactor (EPR) construction plan in Serpong, the subsurface modeling from combination array and single station microtremor data was done. The array and single station microtremor measurement were performed in 9 and 90 sites, respectively, at ± 1 km radius around the EPR site plan. The Vs30 value was calculated from shear wave velocity structure around the investigated area. The soil classification based on Vs30 in the investigated area generally consists of SD (medium soil) and SC (soft rock) class. The EPR site plan its self in the SD class region. Keyword : soil class, shear wave velocity, microtremor, EPR site, Vs30
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Hong, Wen Peng, and Song Chen Jian. "Numerical Simulation of Flue Gas Flow and NH3 Diffusion Properties in SCR System." Advanced Materials Research 881-883 (January 2014): 1819–22. http://dx.doi.org/10.4028/www.scientific.net/amr.881-883.1819.
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The numerical model of SCR denitrification system is established. Simulate the SCR system where installs mixer by the way of installing rectifier grille and three types of guide plates to analyze the changes of velocity, pressure and ammonia concentration before catalyst layer. The results indicate that setting rectifier grille and changing the guide plate size can make velocity and pressure of the whole flow are more stable. In plan 4, the deviation of ammonia concentration at the catalyst inlet section is 3.58%, avoid the phenomenon of ammonia escape and its satisfies the design requirements of SCR denitration system Keywords: SCR denitrification system; rectifier grille; guide plates; pressure drop
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Choi, A.-Young, Sin-Woong Choi, Chang Gyu Woo, and Dong-Hun Han. "Risk Analysis of Waterway Pipes in Rapid Flow Areas using CFD Simulations." Fire Science and Engineering 35, no. 3 (June 30, 2021): 48–52. http://dx.doi.org/10.7731/kifse.70cf0feb.
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In this study, the validity of the theoretical model was examined by applying a CFD model and comparing the results of the existing theoretical equations for predicting the flow velocity inside and outside water pipes, and the dangers around the water pipes in the torrent area in relation to the recent fatal accidents of firefighters was analyzed. The CFD simulation was performed using the commercial analysis program ANSYS R1; the actual accident site was measured and simplified. The flow velocity was measured four times faster inside the canal pipe than the outside, and the results were used to suggest a plan to prevent disaster relief activities and safety accidents.
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Napolitano, Nicola R., Giuseppe D’Ago, Crescenzo Tortora, Gang Zhao, A.-Li Luo, Baitian Tang, Wei Zhang, Yong Zhang, and Rui Li. "Central velocity dispersion catalogue of LAMOST-DR7 galaxies." Monthly Notices of the Royal Astronomical Society 498, no. 4 (September 7, 2020): 5704–19. http://dx.doi.org/10.1093/mnras/staa2409.
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ABSTRACT The Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) is a major facility to carry out spectroscopic surveys for cosmology and galaxy evolution studies. The seventh data release of the LAMOST ExtraGAlactic Survey (LEGAS) is currently available and including redshifts of 193 361 galaxies. These sources are spread over $\sim 11\, 500$ deg2 of the sky, largely overlapping with other imaging (SDSS and HSC) and spectroscopic (BOSS) surveys. The estimated depth of the galaxy sample, r ∼ 17.8, the high signal-to-noise ratio, and the spectral resolution R = 1800, make the LAMOST spectra suitable for galaxy velocity dispersion (VD) measurements, which are invaluable to study the structure and formation of galaxies and to determine their central dark matter content. We present the first estimates of central VD of $\sim 86\, 000$ galaxies in LAMOST footprint. We have used a wrap-up procedure to perform the spectral fitting using ppxf, and derive VD measurements. Statistical errors are also assessed by comparing LAMOST VD estimates with the ones of SDSS and BOSS over a common sample of $\sim 51\, 000$ galaxies. The two data sets show a good agreement, within the statistical errors, in particular when VD values are corrected to 1 effective radius aperture. We also present a preliminary mass–σ relation and find consistency with previous analyses based on local galaxy samples. These first results suggest that LAMOST spectra are suitable for galaxy VD measurements to complement the available catalogues of galaxy internal kinematics in the Northern hemisphere. We plan to expand this analysis to next LAMOST data releases.
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Vagushchenko, L. L., and A. J. Kozachenko. "METHOD OF DISPLAYING THE RESULTS OF TRIAL PLAN FOR COLLISION AVOIDANCE." Shipping & Navigation 32, no. 2 (December 12, 2021): 18–25. http://dx.doi.org/10.31653/2306-5761.32.2021.18-25.
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A method of displaying the results of trial plan for collision avoidance is proposed. It is considered that in general form this plan can be represented by segments of its own ship movement with a constant velocity vector, and sections of this vector change. The basic requirements for displaying trial plan results are formulated. It is accepted that the domains of danger, which are used in solving the tasks to avoid collision are formed at the target and are convex shapes which are symmetrical about the target course line. These domains can be smooth closed curves or closed broken lines (polygons). A program for simulating the execution of an anti-collision plan is proposed to obtain data on this process. It is noted that the risk of passing the target is the greatest one at the moment when the shortest distance between its domain and own ship is small. The vessels’positions, special point and closest to own ship point of the domain up to this moment are considered to be displayed as trial data. Such data along the own ship path to avoid collision are called informational marks. They represent the demanding attention areas, and allow making the reasonable conclusion on acceptability of anticollision plan. Algorithms for calculating elements of informational marks, when using elliptical and polygonal danger domains for targets, are determined. To test the procedure of simulating the implementation of the evading plan and the proposed method of displaying information, a special program was compiled in the Borland Delphi language. This program was used to test the plans to avoid collision in many collision situations applying various forms of targets danger domains. The display of testing results for two segments of the evading plan in a situation with six targets, using circular danger domains with a center shifted towards the nose from the center of the target mass, is presented. Target and own ship dimensions are included in the size of each domain.
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Kim, Juhyun, Maolin Jin, Sang Hyun Park, Seong Youb Chung, and Myun Joong Hwang. "Task Space Trajectory Planning for Robot Manipulators to Follow 3-D Curved Contours." Electronics 9, no. 9 (September 2, 2020): 1424. http://dx.doi.org/10.3390/electronics9091424.
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The demand for robots has increased in the industrial field, where robots are utilized in tasks that require them to move through complex paths. In the motion planning of a manipulator, path planning is carried out to determine a series of the positions of robot end effectors without collision. Therefore, it is necessary to carry out trajectory planning to determine position, velocity, and acceleration over time and to control an actual industrial manipulator. Although several methods have already been introduced for point-to-point trajectory planning, a trajectory plan which moves through multiple knots is required to allow robots to adapt to more complicated tasks. In this study, a trajectory planning based on the Catmull–Rom spline is proposed to allow a robot to move via several points in a task space. A method is presented to assign intermediate velocities and time to satisfy the velocity conditions of initial and final knots. To optimize the motion of the robot, a time-scaling method is presented to minimize the margin between the physical maximum values of velocity and acceleration in real robots and the planned trajectory, respectively. A simulation is then performed to verify that the proposed method can plan the trajectory for moving multiple knots without stopping, and also to check the effects of control parameters. The results obtained show that the proposed methods are applicable to trajectory planning and require less computation compared with the cubic spline method. Furthermore, the robot follows the planned trajectory, and its motion does not exceed the maximum values of velocity and acceleration. An experiment is also executed to prove that the proposed method can be applied to real robotic tasks to dispense glue onto the sole in the shoe manufacturing process. The results from this experiment show that the robot can follow the 3-D curved contour in uniform speed using the proposed method.
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Omiya, Masashi, Bun'ei Sato, Hiroki Harakawa, Masayuki Kuzuhara, Teruyuki Hirano, and Norio Narita. "Search for Low-Mass Planets Around Late-M Dwarfs Using IRD." Proceedings of the International Astronomical Union 8, S293 (August 2012): 201–3. http://dx.doi.org/10.1017/s1743921313012830.
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AbstractWe have a plan to conduct a Doppler planet search for low-mass planets around nearby middle-to-late M dwarfs using IRD. IRD is the near-infrared high-precision radial velocity instrument for the Subaru 8.2-m telescope. We expect to achieve the accuracy of the radial velocity measurements of 1 m/s using IRD with a frequency comb as a wavelengh calibrator. Thus, we would detect super-Earths in habitable zone and low-mass rocky planets in close-in orbits around late-M dwarfs. In this survey, we aim to understand and discuss statistical properties of low-mass planets around low-mass M dwarfs compared with those derived from theoretical simulations.
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Farhan, Muhammad, and Gunawan Handayani. "Shear Wave Velocity Analysis of 2-D Multichannel Analysis of Surface Wave (MASW) to investigate subsurface Fault of Alternative Bridge Construction in Kelok Sago Jambi." Jurnal Matematika dan Sains 25, no. 1 (September 2020): 18–20. http://dx.doi.org/10.5614/jms.2020.25.1.4.
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Every geotechnical measurement requires geophysical methods to classify soil types under the ground. S-wave velocity (Vs), P-wave velocity (Vp), and density (ρ), are the most important parameters in the classification of soils. There are various methods to determine Vs, one of them is P-S logging method. However, this method is less suitable to be applied in urban areas due to the difficulties of data acquisition and high expense in operational costs. In 1999, a seismic method uses surface waves to de-termine Vs profile with a higher signal to noise ratio which was known by the name of Multichannel Analysis of Surface Waves (MASW). A surface wave, especially Rayleigh wave, creeps slowly on the surface with a larger amplitude than a body wave. The wavelengths of the surface wave will disperse in the layers system i.e. the phase velocity of the surface waves is now func-tion of frequency. MASW 2-D method is used in this paper to determine subsoil properties and to identify the fault under the bridge abutments plan (abutment 1 and abutment 2) in Kelok Sago Jambi.
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Carcione, José M., and Flavio Poletto. "Sound velocity of drilling mud saturated with reservoir gas." GEOPHYSICS 65, no. 2 (March 2000): 646–51. http://dx.doi.org/10.1190/1.1444761.
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Knowledge of the in‐situ sound velocity of drilling mud can be used in mud‐pulse acoustic telemetry for evaluating the presence and amount of gas invasion in the drilling mud. We propose a model for calculating the in‐situ density and sound velocity of water‐based and oil‐based drilling muds containing formation gas. Drilling muds are modeled as a suspension of clay particles and high‐gravity solids in water or oil, with the acoustic properties of these fluids depending on pressure and temperature. Since mud at different depths experiences different pressures and temperatures, downhole mud weights can be significantly different from those measured at the surface. Taking this fact into consideration, we assume constant clay composition and obtained the fraction of high‐gravity solids to balance the formation pressure corresponding to a given drilling plan. This gives the in‐situ density of the drilling mud, which together with the bulk moduli of the single constituents allow us to compute the sound velocity using Reuss’s model. In the case of oil‐based muds, we take into account the gas solubility in oil. When gas goes into solution, the mud is composed of solid particles, live oil and, eventually, free gas. A phenomenological model based on a continuous spectrum of relaxation mechanisms is used to describe attenuation due to mud viscosity. The calculations for water‐based and oil‐based muds showed that the sound velocity is strongly dependent on gas saturation, fluid composition, and drilling depth.
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Geng, Xiongfei, Yongcai Wang, Ping Wang, and Baochen Zhang. "Motion Plan of Maritime Autonomous Surface Ships by Dynamic Programming for Collision Avoidance and Speed Optimization." Sensors 19, no. 2 (January 21, 2019): 434. http://dx.doi.org/10.3390/s19020434.
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Maritime Autonomous Surface Ships (MASS) with advanced guidance, navigation, and control capabilities have attracted great attention in recent years. Sailing safely and efficiently are critical requirements for autonomous control of MASS. The MASS utilizes the information collected by the radar, camera, and Autonomous Identification System (AIS) with which it is equipped. This paper investigates the problem of optimal motion planning for MASS, so it can accomplish its sailing task early and safely when it sails together with other conventional ships. We develop velocity obstacle models for both dynamic and static obstacles to represent the potential conflict-free region with other objects. A greedy interval-based motion-planning algorithm is proposed based on the Velocity Obstacle (VO) model, and we show that the greedy approach may fail to avoid collisions in the successive intervals. A way-blocking metric is proposed to evaluate the risk of collision to improve the greedy algorithm. Then, by assuming constant velocities of the surrounding ships, a novel Dynamic Programming (DP) method is proposed to generate the optimal multiple interval motion plan for MASS. These proposed algorithms are verified by extensive simulations, which show that the DP algorithm provides the lowest collision rate overall and better sailing efficiency than the greedy approaches.
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Fan, Cheng, Lei Zhang, Qizhi Zhao, Jun Zhao, Ji Zhao, and Lining Sun. "Modeling and optimization of material removal influenced by sliding velocity in polishing." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 233, no. 4 (May 21, 2018): 1127–35. http://dx.doi.org/10.1177/0954405418774589.
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The high-precision part surfaces are usually finished by the corrective polishing to improve the surface form accuracy. This article proposes a new method to model and optimize the material removal in the polishing process. This method assumes that the material removal rate in polishing follows the Preston’s equation, and the material removal profile is obtained by integrating the material removal index along the tool path at each unit area of the tool/workpiece contact. The focus is on the effect of the sliding velocity on the material removal profile. Results indicate that the shape of the removal profile is affected by the angular spindle velocity, angular feed velocity and tool path radius. A series of simulation and practical polishing experiments were conducted to verify the proposed model. The tending gene of the removal profile is defined and derived. By using the principle of maximum tending gene, the material removal profile is optimized, which is helpful to plan the process parameter properly in polishing.
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Lanzarone, Peter, Xukai Shen, Andrew Brenders, Ganyuan Xia, Joe Dellinger, Gabriel Ritter, and John Etgen. "Innovative application of full-waveform inversion applied to extended wide-azimuth marine streamer seismic data in a complex salt environment." GEOPHYSICS 87, no. 3 (February 25, 2022): B193—B205. http://dx.doi.org/10.1190/geo2021-0374.1.
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We demonstrate the application of full-waveform inversion (FWI) guided velocity model building to an extended wide-azimuth towed streamer (EWATS) seismic data set in the Gulf of Mexico. Field data are collected over a historically challenging imaging area, colloquially called the “grunge zone” due to the formation of a compressional allosuture emplaced between two colliding salt sheets. These data have a poor subsalt image below the suture with conventional narrow-azimuth data. Additional geologic complexities are observed including high-velocity carbonate carapace near the top of salt and multiple intrasalt sedimentary inclusions. As such, improved seismic imaging is required to plan and execute wells targeting subsalt strata. Significant improvements to the velocity model and subsalt image have been evident with wide-azimuth towed streamer and later EWATS data using conventional top-down velocity model building approaches. Subsequently, high-impact improvements have been made using EWATS data with an FWI velocity model building workflow; this study represents an early successful application of FWI used to update salt body geometries from streamer seismic data, wherein many prior applications were limited to improving sedimentary velocities. Later petrophysical data have verified the new FWI-derived model, which has significantly increased confidence in the structural and stratigraphic interpretation of subsalt reservoir systems below the grunge zone.
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Yu, Fu, Yan Jin, Kang Ping Chen, and Mian Chen. "Pore-pressure prediction in carbonate rock using wavelet transformation." GEOPHYSICS 79, no. 4 (July 1, 2014): D243—D252. http://dx.doi.org/10.1190/geo2013-0277.1.
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Accurate prediction of pore pressure can assist engineers to better work out and optimize an oilfield development plan. Because the P-wave velocity only experiences small-scale fluctuations for pore-pressure change in carbonate rocks, existing well-known pore-pressure prediction methods are incapable of predicting pore pressure in carbonate rocks with field-required accuracy. We evaluated a new method based on the P-wave velocity decomposition and wavelet transformation to predict pore pressure in carbonate rocks. The P-wave velocity was decomposed into contributions from the pore fluid and the rock framework using Biot’s theory. The effect of lithology, pore structure, porosity, and pore pressure on P-wave velocity was studied by theoretical analysis and experiments. Rapid triaxial rock-system tests were carried out to measure the P- and S-wave velocities when pore pressure, pore structure, and porosity were changed, and X-ray diffraction tests were used to measure mineral components. The small-scale fluctuations of the P-wave velocity can be extracted and amplified using wavelet transformation. We found that the small-scale fluctuations of the P-wave velocity were caused by pore-pressure change in carbonate rocks and the large-scale fluctuations of the P-wave velocity depended on the rock framework. Overpressure formation can be identified by the high-frequency detail of wavelet transformation of P-wave velocity. A pore-pressure prediction model relating the contribution from the pore fluid to the P-wave velocity was developed. This model is an improvement over existing pore-pressure prediction methods that mainly rely on empirical relations between the P-wave velocity and the pore pressure. This new method was successfully applied to carbonate rocks in Tazhong Block, Tarim oilfield, demonstrating the feasibility of the proposed pore-pressure prediction method.
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Pirkovic, I., and O. Atanackovic. "FBILI method for the two-level atom line formation in media with low velocity fields." Serbian Astronomical Journal, no. 189 (2014): 53–67. http://dx.doi.org/10.2298/saj1489053p.
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In this paper we generalized the fast convergent Forth-and-Back Implicit Lambda Iteration (FBILI) method to the solution of the two-level atom line transfer problems in media with low velocity fields using the observer?s reference frame. In order to test the accuracy and the convergence properties of the method we solved several astrophysically important benchmark problems of the NLTE line formation: in a plan-parallel differentially expanding medium of finite thickness, and in spherically symmetric stellar atmospheres, both static and expanding. We compared our solutions with those obtained by other authors using different numerical methods.
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Lazaridis, Georgios Theodoros, Kyriaki Fellachidou, and Maria-Nefeli Georgaki. "Paleohydrology of the Stefanina Cave (Greece)." Bulletin of the Geological Society of Greece 57, no. 1 (July 8, 2021): 52. http://dx.doi.org/10.12681/bgsg.26168.
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The development of hypergene Stefanina Cave, the hydrological conditions, and the maximum discharge of the paleo-flow are studied, based on its pattern in ground-plan, the geometry of the passage, and the peak flow velocity from the dimensions of the scallops. The village of Stefanina is located East of Thessaloniki and the cave NE of the village. A study was conducted measuring the orientation of the discontinuities of the rocks inside and outside the cave, the scallops in various sites to estimate the flow velocities, and in addition, were taken photographs for the full analysis of its cross-section. The cave-in ground-plan has a pattern of branches, which is often associated with recharging through karstic depressions. The shape of the passages is both curvilinear and angular, depending on the foliage and the fractures. The symmetrical phreatic passage shape has been evolved to a vadose canyon, forming a keyhole passage in cross-section. This is indicative of a water table drop. The scallops are visible in a meandering channel, where the discharge of the paleo-flow is estimated. The estimated peak flow velocity ranges from 0.4 to 2.7 m / s, while the area-specific peak flow discharge is estimated to be 2.2 m3/s. On the one hand, the scallops represent the peak flow velocity, on the other hand, the karst springs have a limited maximum discharge, regardless of the size of the catchment, making it impossible to use the calculated paleo-discharge to estimate the respective catchment area.
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Rai, Ajay Kumar, and Ritu Tiwari. "Collision Avoidance in Dynamic Environment by Estimation of Velocity and Location of Object by Robot using Parallax." International Journal of Robotics Applications and Technologies 3, no. 2 (July 2015): 63–75. http://dx.doi.org/10.4018/ijrat.2015070104.
Full textAbstract:
Collision avoidance is a challenging problem in robot navigation. There are two type of collision avoidance approach i.e. path planning algorithm and control algorithm. Control algorithm proven very useful for dynamic environment. In control method robot use sensing to close a feedback path and interact with the environment. This sensing feedback loop can be completed by using Camera in robot.Visual parallax is very useful for generation of 3D information of environment for robotic system. Here the authors describe the use of visual parallax in humanoid robotic system for estimation of velocity and location of object that present in environment. The location and velocity of object gives the useful information to plan a collision free path by robot in that environment. Accuracy, robustness, and applicability of this method wastest by simulation. The authors show that this approach gives an accurate and robust estimation of velocity and a distance of object. This information simplifies the difficult task of collision avoidance in dynamic environment.
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Hindmarsh, Richard C. A. "An observationally validated theory of viscous flow dynamics at the ice-shelf calving front." Journal of Glaciology 58, no. 208 (2012): 375–87. http://dx.doi.org/10.3189/2012jog11j206.
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AbstractAn analytical theory is developed for ice flow velocity in a boundary layer couplet at the calving front. The theory has simple quantitative characteristics that relate ice front velocity to thickness, strain rate and shelf width, matching one set of empirically derived relationships (Alley and others, 2008) and implying that these relationships predict ice velocity rather than calving rate. The two boundary layers are where longitudinal and transverse flow fields change from the interior flow to patterns consistent with the calving-front stress condition. Numerical simulations confirm the analytical theory. The quantitative predictions of the theory have low sensitivity to unmeasured parameters and to shelf plan aspect ratio, while its robustness arises from its dependence on the scale invariance of the governing equations. The theory provides insights into calving, the stability of ice-shelf calving fronts, the stability of the grounding line of laterally resisted ice streams, and also suggests that the calving front is an instructive dynamical analogue to the grounding line.
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Yu, Yingjie, and Yong Li. "An Improved Clutter Suppression Method for Weather Radars Using Multiple Pulse Repetition Time Technique." Advances in Meteorology 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/8173643.
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This paper describes the implementation of an improved clutter suppression method for the multiple pulse repetition time (PRT) technique based on simulated radar data. The suppression method is constructed using maximum likelihood methodology in time domain and is called parametric time domain method (PTDM). The procedure relies on the assumption that precipitation and clutter signal spectra follow a Gaussian functional form. The multiple interleaved pulse repetition frequencies (PRFs) that are used in this work are set to four PRFs (952, 833, 667, and 513 Hz). Based on radar simulation, it is shown that the new method can provide accurate retrieval of Doppler velocity even in the case of strong clutter contamination. The obtained velocity is nearly unbiased for all the range of Nyquist velocity interval. Also, the performance of the method is illustrated on simulated radar data for plan position indicator (PPI) scan. Compared with staggered 2-PRT transmission schemes with PTDM, the proposed method presents better estimation accuracy under certain clutter situations.
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Rousseau, Célia, Charalambos Papaxanthis, Jérémie Gaveau, Thierry Pozzo, and Olivier White. "Initial information prior to movement onset influences kinematics of upward arm pointing movements." Journal of Neurophysiology 116, no. 4 (October 1, 2016): 1673–83. http://dx.doi.org/10.1152/jn.00616.2015.
Full textAbstract:
To elaborate a motor plan and perform online control in the gravity field, the brain relies on priors and multisensory integration of information. In particular, afferent and efferent inputs related to the initial state are thought to convey sensorimotor information to plan the upcoming action. Yet it is still unclear to what extent these cues impact motor planning. Here we examined the role of initial information on the planning and execution of arm movements. Participants performed upward arm movements around the shoulder at three speeds and in two arm conditions. In the first condition, the arm was outstretched horizontally and required a significant muscular command to compensate for the gravitational shoulder torque before movement onset. In contrast, in the second condition the arm was passively maintained in the same position with a cushioned support and did not require any muscle contraction before movement execution. We quantified differences in motor performance by comparing shoulder velocity profiles. Previous studies showed that asymmetric velocity profiles reflect an optimal integration of the effects of gravity on upward movements. Consistent with this, we found decreased acceleration durations in both arm conditions. However, early differences in kinematic asymmetries and EMG patterns between the two conditions signaled a change of the motor plan. This different behavior carried on through trials when the arm was at rest before movement onset and may reveal a distinct motor strategy chosen in the context of uncertainty. Altogether, we suggest that the information available online must be complemented by accurate initial information.
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Leclercq, Guillaume, Gunnar Blohm, and Philippe Lefèvre. "Accounting for direction and speed of eye motion in planning visually guided manual tracking." Journal of Neurophysiology 110, no. 8 (October 15, 2013): 1945–57. http://dx.doi.org/10.1152/jn.00130.2013.
Full textAbstract:
Accurate motor planning in a dynamic environment is a critical skill for humans because we are often required to react quickly and adequately to the visual motion of objects. Moreover, we are often in motion ourselves, and this complicates motor planning. Indeed, the retinal and spatial motions of an object are different because of the retinal motion component induced by self-motion. Many studies have investigated motion perception during smooth pursuit and concluded that eye velocity is partially taken into account by the brain. Here we investigate whether the eye velocity during ongoing smooth pursuit is taken into account for the planning of visually guided manual tracking. We had 10 human participants manually track a target while in steady-state smooth pursuit toward another target such that the difference between the retinal and spatial target motion directions could be large, depending on both the direction and the speed of the eye. We used a measure of initial arm movement direction to quantify whether motor planning occurred in retinal coordinates (not accounting for eye motion) or was spatially correct (incorporating eye velocity). Results showed that the eye velocity was nearly fully taken into account by the neuronal areas involved in the visuomotor velocity transformation (between 75% and 102%). In particular, these neuronal pathways accounted for the nonlinear effects due to the relative velocity between the target and the eye. In conclusion, the brain network transforming visual motion into a motor plan for manual tracking adequately uses extraretinal signals about eye velocity.