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Journal articles on the topic 'Velocity plan'
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1
Sciutti, Alessandra, Laurent Demougeot, Bastien Berret, et al. "Visual gravity influences arm movement planning." Journal of Neurophysiology 107, no. 12 (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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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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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 (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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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 (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 (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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Cui, JiaXiang, and Ke Fang. "UAV Control With Terminal Velocity Vector Constraints." Journal of Physics: Conference Series 2832, no. 1 (2024): 012011. http://dx.doi.org/10.1088/1742-6596/2832/1/012011.
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Abstract The paper focuses on the UAV(Unmanned Aerial Vehicle) control strategy with terminal velocity vector constraints. Given the constraints on the position, velocity magnitude and velocity vector of points A and B, it uses a polynomial trajectory to plan a smooth continuous way that satisfies the constraints. To resolve the problem that the traditional cascade PID cannot control the position and velocity at the same time, it improves the cascade PID structure. Finally, a case study is provided to prove the algorithmic strategy. The result shows that, it satisfies the constraints on the terminal velocity vector.
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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, et al. "Experimental and Numerical Analysis of Gas/Powder Flow for Different LMD Nozzles." Metals 10, no. 5 (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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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 (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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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 (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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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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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 (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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Eden, D. J., T. J. T. Moore, M. J. Currie, et al. "CHIMPS2: survey description and 12CO emission in the Galactic Centre." Monthly Notices of the Royal Astronomical Society 498, no. 4 (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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Shaffick, Brendan. "A Theoretical Training Plan and Facility for Ontario-Based Olympic Weightlifters." American Journal of Recreation and Sports 2, no. 1 (2023): 1–28. http://dx.doi.org/10.47672/ajrs.1450.
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Olympic Weightlifting is a sport where athletes of different weight classes utilize either the Snatch or Clean and Jerk (CJ) technique to lift the heaviest load overhead. This case study describes the training program for a team of Senior (age; 18-35 years) Olympic weightlifters during a normal competitive season. The team of Olympic weightlifters will be participating in team training 3 to 4 times a week; however, variations will occur on the training schedule for each individual athlete based on the on-going testing results. Each athlete will also participate in an additional day of training noted as the “active rest” day which prioritizes injury management for the individual based on their test results, during the training season. In conclusion, the training program in this study provided an insight on implementing velocity profiling into an Olympic weightlifting training program. The device in this study (PUSH Band) quantifies the bar movement via the force velocity curve and the coach has a clearer means in which to determine the repetitions that follow. This study is based around the theoretical idea of implementing a means in which to avoid the traditional periodization rep schema to administer training volume, but rather utilize new technologies. To conclude, methods that accommodate for velocity profiles to determine volume in conjunction with 1RM percentages and a coach’s discretion may allow for more efficient training and a reduction in excess fatigue.
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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 (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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Wu, Nengkai, Dongyao Jia, Ziqi Li, and Zihao He. "Trajectory Planning of Robotic Arm Based on Particle Swarm Optimization Algorithm." Applied Sciences 14, no. 18 (2024): 8234. http://dx.doi.org/10.3390/app14188234.
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Achieving vibration-free smooth motion of industrial robotic arms in a short period is an important research topic. Existing path planning algorithms often sacrifice smoothness in pursuit of efficient motion. A robotic trajectory planning particle swarm optimization algorithm (RTPPSO) is introduced for optimizing joint angles or paths of mechanical arm movements. The RTPPSO algorithm is enhanced through the introduction of adaptive weight strategies and random perturbation terms. Subsequently, the RTPPSO algorithm is utilized to plan selected parameters of an S-shaped velocity profile, iterating to obtain the optimal solution. Experimental results demonstrate that this velocity planning algorithm significantly improves the acceleration of the robotic arm, surpassing traditional trial-and-error velocity planning methods.
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Chen, Shengtao, Yuhan Zhang, Tianyu Su, and Yongjun Gong. "PIV Experimental Research and Numerical Simulation of the Pigging Process." Journal of Marine Science and Engineering 12, no. 4 (2024): 549. http://dx.doi.org/10.3390/jmse12040549.
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The initial running speed of the pig during gas–liquid two-phase pipeline pigging can significantly influence the velocities of both gas and liquid phases within the pipeline. However, due to the complexity and limited understanding of these velocity variations, developing an effective operational plan for pigging becomes challenging. To enhance pigging efficiency and effectively seal the pig, it is crucial to monitor the velocity variations in the gas–liquid phase within the pipeline. In this study, an experimental platform was established to facilitate precise observation of these variations. Particle image velocimetry (PIV) technology was employed for a comprehensive understanding of gas–liquid two-phase velocities during pig operation in the pipeline. The experimental results demonstrated that increasing both the velocity and the initial liquid level height of the pig resulted in a corresponding augmentation of velocity fluctuation range. Specifically, at a holdup rate of 30%, there was a 10% reduction in the maximum liquid-phase velocity, while at a holdup rate of 25%, this reduction amounted to 16% compared to the pigging velocity.
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Burns, R. A., T. W. Fahringer, Jr., and P. M. Danehy. "Hybrid Pulse-Burst / Cross-Correlation DGV For High-Speed Flow Measurements At 100 KHz." Proceedings of the International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics 20 (July 11, 2022): 1–20. http://dx.doi.org/10.55037/lxlaser.20th.26.
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Hybrid pulse-burst Doppler global velocimetry (PB-DGV)/pulse-burst, cross-correlation DGV (PB-CC-DGV) was demonstrated for the first time in the NASA Langley 4-foot Supersonic Unitary Plan Wind Tunnel, allowing simultaneous acquisition of mean and instantaneous high-repetition-rate velocity fields. The technique was used to make planar velocity measurements across an oblique shockwave generated by a large splitter plate set at a -2° angle of attack in a Mach 2.4 flow. Sequences of >100 consecutive instantaneous velocity images were obtained at a rate of 100 kHz. Velocity fields from both aspects of the hybrid measurement indicated errors less than 1-percent of anticipated velocities. Likewise, all assessments of measurement precision were approximately 1.6-percent of the local velocities. Additional demonstrations in different flowfields including a subsonic axi-symmetric jet and a supersonic Mars reentry vehicle model further illustrate the utility of the new hybrid method.
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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 (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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Li, Yuting, Zhiyao Song, Guoqiang Peng, et al. "Modeling Hydro-Dynamics in a Harbor Area in the Daishan Island, China." Water 11, no. 2 (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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Tan, Sirui, Gboyega Ayeni, Jaewoo Park, et al. "Integrated velocity and attenuation model building: Sakhalin case study." Leading Edge 41, no. 3 (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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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 (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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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 (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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Reno Arief Rachman, Haryo Dwito Armono, Dinar Catur istiyanto, Khusnul Setia Wardani, Hanah Khoirunnisa, and Reni Wijayanti. "Study of Hydrodynamic Patterns of Tanjung Pasir Banten Waters to Support the NCICD Sea Wall Development Plan." Journal of Geoscience, Engineering, Environment, and Technology 8, no. 1 (2023): 1–9. http://dx.doi.org/10.25299/jgeet.2023.8.1.10801.
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Numerical modeling of hydrodynamics (HD) around the Tanjung Pasir Waters was carried out using MIKE 21 HD Flexible Mesh software to get the current velocity pattern conditions during the west and east monsoons. This activity is to support the NCICD sea wall construction plan. In addition, the results that will be obtained in this modeling are the conditions of the speed and direction of the current in various tidal conditions during spring and neap. The data used in this modeling include wind speed and direction, wave height, wave period, and wave direction. Based on the research that has been done, the validation value of Naotide tidal data on tidal field data is 93.8 %. HD MIKE 21 modeling results on field data have a validation value of 93.4 %. Extract points 4 and 5 which are the northernmost, have the highest current velocity values compared to the other points. In addition, when heading to the high tide phase, both spring and neap conditions, the current velocity value has the highest value.
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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 (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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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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Wendt, Anke S., Monzurul Alam, and Joao Paulo Castagnoli. "Sand injectite mapping using a resistivity-velocity transform function." Leading Edge 40, no. 3 (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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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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Galyaev, A. A., V. P. Yakhno, P. V. Lysenko, L. M. Berlin, and M. E. Buzikov. "Optimization of Interception Plan for Rectilinearly Moving Targets." Avtomatika i telemehanika, no. 10 (December 15, 2023): 18–36. http://dx.doi.org/10.31857/s0005231023100033.
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The article considers the problem of combinatorial optimization of interception of rectilinearly moving targets as a modification of the traveling salesman problem. New macro characteristics and definitions for this problem are introduced and used to classify the obtained solutions. Vector criteria composed of several important for applications functionals are described. The principles of nowaitingand maximum velocity are proved for two types of criteria. An intelligent brute-force algorithm with dynamic programming elements for finding optimal plans according to the introduced intercept criteria is proposed and implemented. Statistics of solutions of the developed algorithm is collected for a set of different initial parameters and the proposed macro characteristics are investigated. The conclusions about their applicability as local rules for the greedy algorithm for finding a suboptimal intercept plan are drawn.
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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 (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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Nusantara, Danayanti Azmi Dewi, Feriza Nadiar, and Nastasia Festy Margini. "Drainage Analysis of the West Outer Ring Road Surabaya." Civilla : Jurnal Teknik Sipil Universitas Islam Lamongan 8, no. 1 (2023): 73–86. http://dx.doi.org/10.30736/cvl.v8i1.1050.
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The development of West Outer Ring Road, abbreviated as JLLB, to improve the quality of infrastructure in the City of Surabaya. A breakthrough is needed by opening a new existing road section to break down traffic jams that lead to the main corridor section of the central city. The JLLB area, originally a green open area, was converted into a road area. This condition will cause changes in the sum of rainwater runoff that occur. The JLLB also intersects with the railroad tracks. A drainage system plan to ensure no puddles on the road, even through the railroad tracks. The method of this study follows hydrological and hydraulics analysis of the drainage systems. The results of drainage analysis on West Outer Ring Road, abbreviated as JLLB, there are several typical canal dimensions needed. All velocities can be controlled in the range of permissible velocity. The minimum velocity is 0,4 m/sec, and the maximum is 0,873 m/sec. The maximum planned discharge is 1,381 m3/sec. The capacity of boezem is planned to suit 5,104 hr of rain duration. Based on all that results, the drainage analysis of JLLB would be great if implemented according to plan.
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Guo, Songling, Lijun Song, Shicheng Wang, Jinfu Li, and Yuanyuan Tian. "Thin reservoir prediction technology with sensitive parameters of tight gas in southwest Ordos Basin." Advances in Computer and Engineering Technology Research 1, no. 2 (2024): 12. http://dx.doi.org/10.61935/acetr.2.1.2024.p12.
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In the southwest of Ordos Basin, the loess layer is very thick, the surface elevation changes rapidly, and the near-surface low-velocity zone velocity changes greatly in vertical and horizontal directions, resulting in prominent static correction problems. Affected by the strong absorption of the loess layer, the effective frequency band of the original data is narrow, the apparent main frequency is low, and the "double high" processing is difficult. The reservoirs of He-8 and Shan-1 are deep-buried, thin and dense, and their lateral changes are fast. In this paper, the sensitive data of "two widths and one height" 3D seismic is optimized to obtain high-quality sensitive data. The sensitive orientation is optimized by combining drilling data, and the sensitive parameter based on pre-stack inversion technology is adopted to improve the prediction accuracy of thin reservoirs. The new Chengtan-3-Long19 He-8 sand belt was discovered, the well location deployment plan was optimized, the efficient drilling of horizontal Wells was supported and the fracturing plan was optimized. 26 well locations were deployed using 3D seismic, 11 were completed drilling, and 9 were class I + II, an increase of 30% compared with 2D seismic.
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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 (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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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 (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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Poletto, Flavio, José M. Carcione, Massimo Lovo, and Francesco Miranda. "Acoustic velocity of seismic‐while‐drilling (SWD) borehole guided waves." GEOPHYSICS 67, no. 3 (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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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 (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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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 (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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Zaki, Sheikh Ahmad, Saidatul Sharin Shuhaimi, Ahmad Faiz Mohammad, Mohamed Sukri Mat Ali, Khairur Rijal Jamaludin, and Mardiana Idayu Ahmad. "Development of a Prediction Model of the Pedestrian Mean Velocity Based on LES of Random Building Arrays." Buildings 12, no. 9 (2022): 1362. http://dx.doi.org/10.3390/buildings12091362.
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Wind speed in urban areas is influenced by the interaction between wind flow and building geometry; at the pedestrian level, the interaction is more complex, particularly with high building density. This study investigated the wind velocity distribution and the mean velocity ratio at the pedestrian level using the large-eddy simulation (LES) database based on random building arrays of several plan area densities, λp. The heights of random buildings are between 0.36 h and 3.76 h where h = 0.025 m. Mean streamwise velocity profiles were obtained at the pedestrian level for all arrays and were found to decrease as λp increased. Wind flow patterns at the pedestrian level were highly influenced by adjacent buildings, especially in denser conditions, λp > 0.17. The pedestrian-level mean velocity was obtained around each building, and the relationship between the local mean velocity ratio, Vp(t) and the local frontal area density, λf(t) was analyzed. Subsequently, a prediction model was formulated based on the building’s aspect ratio, αp; the correlation for high-rise buildings with 2.64 h ≤ αp ≤ 3.76 h was high at 0.8, while a lower correlation was obtained for lower buildings due to random positioning and surrounding geometric effects. Therefore, the impact of high-rise buildings on pedestrian wind velocity can be estimated more accurately using the formulated model.
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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 (2016): 1673–83. http://dx.doi.org/10.1152/jn.00616.2015.
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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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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 (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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Gao, Wei, Mengxue Han, Zhao Wang, Lihui Deng, Hongjian Wang, and Jingfei Ren. "Research on Method of Collision Avoidance Planning for UUV Based on Deep Reinforcement Learning." Journal of Marine Science and Engineering 11, no. 12 (2023): 2245. http://dx.doi.org/10.3390/jmse11122245.
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A UUV can perform tasks such as underwater surveillance, reconnaissance, surveillance, and tracking by being equipped with sensors and different task modules. Due to the complex underwater environment, the UUV must have good collision avoidance planning algorithms to avoid various underwater obstacles when performing tasks. The existing path planning algorithms take a long time to plan and have poor adaptability to the environment. Some collision-avoidance planning algorithms do not take into account the kinematic limitations of the UUV, thus placing high demands on the performance and control algorithms of UUV. This article proposes a PPO−DWA collision avoidance planning algorithm for the UUV under static unknown obstacles, which is based on the proximal policy optimization (PPO) algorithm and the dynamic window approach (DWA). This algorithm acquires the obstacle information from forward-looking sonar as input and outputs the corresponding continuous actions. The PPO−DWA collision avoidance planning algorithm consists of the PPO algorithm and the modified DWA. The PPO collision avoidance planning algorithm is only responsible for outputting the continuous angular velocity, aiming to reduce the difficulty of training neural networks. The modified DWA acquires obstacle information and the optimal angular velocity from the PPO algorithm as input, and outputs of the linear velocity. The collision avoidance actions output by this algorithm meet the kinematic constraints of UUV, and the algorithm execution time is relatively short. The experimental data demonstrates that the PPO−DWA algorithm can effectively plan smooth collision-free paths in complex obstacle environments, and the execution time of the algorithm is acceptable.
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Lanzarone, Peter, Xukai Shen, Andrew Brenders, et al. "Innovative application of full-waveform inversion applied to extended wide-azimuth marine streamer seismic data in a complex salt environment." GEOPHYSICS 87, no. 3 (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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Ferri-Caruana, Ana, Elena Muñoz-Gómez, Sara Mollà-Casanova, Pablo Camarón-Mallén, and Pilar Serra-Añó. "impact of velocity-based movement on electromyography activity in standard lower-limb strength exercises." Scientific Journal of Sport and Performance 2, no. 3 (2023): 314–25. http://dx.doi.org/10.55860/mxqo3997.
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Previous research has shown that the velocity of movement can influence muscle activation. However, no studies have investigated the impact of movement velocity under the same load conditions on electromyography (EMG) activity in knee and hip extensors. This study aims to compare the mean muscle activation of gluteus maximus [GM], biceps femoris [BF], semitendinosus [ST] and rectus femoris [RF] in three hip extension exercises (i.e., squat [SQ], hip thrust [HT] and Bulgarian squat [BS]) with two different movement velocities (i.e., maximum velocity [MV] and controlled velocity [CV]). Fifteen physically active students participated. The mean EMG activity of all targeted muscles was measured. Maximum Voluntary Isometric Contraction was used to normalize EMG muscle activation. All muscles were activated to a greater extent in BS at MV than in the same exercise performed at CV. However, during the SQ exercise, EMG differences between velocities were only obtained for BF and GM, and in HT, only for GM (p < .05). In conclusion, higher velocity involves higher activation of the lower-limb muscles, depending on the physical test, and this can be used to better plan the functional recovery of injury, taking it into consideration for intensity progression and avoiding the risks of overly strenuous exercises.
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Hoenig, Wolfgang, T. K. Kumar, Liron Cohen, et al. "Multi-Agent Path Finding with Kinematic Constraints." Proceedings of the International Conference on Automated Planning and Scheduling 26 (March 30, 2016): 477–85. http://dx.doi.org/10.1609/icaps.v26i1.13796.
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Multi-Agent Path Finding (MAPF) is well studied in both AI and robotics. Given a discretized environment and agents with assigned start and goal locations, MAPF solvers from AI find collision-free paths for hundreds of agents with user-provided sub-optimality guarantees. However, they ignore that actual robots are subject to kinematic constraints (such as finite maximum velocity limits) and suffer from imperfect plan-execution capabilities. We therefore introduce MAPF-POST, a novel approach that makes use of a simple temporal network to postprocess the output of a MAPF solver in polynomial time to create a plan-execution schedule that can be executed on robots. This schedule works on non-holonomic robots, takes their maximum translational and rotational velocities into account, provides a guaranteed safety distance between them, and exploits slack to absorb imperfect plan executions and avoid time-intensive replanning in many cases. We evaluate MAPF-POST in simulation and on differential-drive robots, showcasing the practicality of our approach.
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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 (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.
Full textAbstract:
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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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 (2018): 1127–35. http://dx.doi.org/10.1177/0954405418774589.
Full textAbstract:
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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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.
Full textAbstract:
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.