Landing Position Research Articles

Biomechanical Analysis of Injury Risk in Two High-Altitude Landing Positions Using Xsens Inertial Units and EMG Sensors

Biomechanical Analysis of Injury Risk in Two High-Altitude Landing Positions Using Xsens Inertial Units and EMG Sensors

Table tennis ball landing control in a robotic system by cameras

Abstract Controlling the landing position of a spinning ball is difficult when using a table tennis robot. A complete physical model requires the factoring in of aerodynamic elements and object collisions, and inaccurate environmental coefficients would increase the landing position error. This study proposed a landing position control method based on a cascade neural network (CNN) that consists of forward and recurrent neural networks (RNNs). The forward NNs are used to estimate the velocity of the outgoing ball according to the velocity and acceleration of the incoming ball captured by cameras and the desired velocity of the outgoing ball. The RNN is employed to reverse-predict ball displacement based on the state of the incoming ball, desired landing point, and ball flight duration. The experiments verified that the method proposed in this study achieved control of differently spinning balls more effectively than the locally weighted regression (LWR)-based model did. The success rate of the CNN at two of six desired landing points was 25.9% and 32.9% higher, respectively, compared with use of the LWR-based model.

Dynamic collaborative truck-drone delivery with en-route synchronization and random requests

Coordinated truck and drone delivery is gaining popularity in logistics as it can greatly reduce operation costs. However, existing studies on related operations management problems typically ignore the following important features: (i) the random appearance of requests, which require operators to dynamically respond to the requests; and (ii) the decisions of optimal launch and retrieval locations for trucks and drones instead of fixed to customer locations, which can significantly impact the overall time costs. To tackle these challenges, this study investigates the dynamic collaborative truck-drone routing problem with randomly arriving requests and synchronization on routes. We model the problem as a Markov Decision Process (MDP) and solve the MDP via a reinforcement learning (RL) approach. The proposed RL approach determines: (i) whether each request should be serviced upon arrival, (ii) which truck or drone should be assigned for the request, and (iii) the optimal en-route take-off and landing positions for paired trucks and drones. We further employ a framework of decentralized learning and centralized dispatching in RL to increase performance. Numerical experiments are conducted to assess the proposed solution approach on instances generated based on both the Solomon dataset and real-world operational data of a logistics operator in Singapore over several benchmark algorithms under various battery endurance levels of drones and distinct transportation scenarios including node-based dynamic collaborative truck-drone routing problem, dynamic non-collaborative truck and drone routing problem, and dynamic vehicle routing problem. The results show that our RL solution outperforms the benchmark algorithm in total profit by an average of 28.03 %, and our en-route takeoff and landing scenario outperforms the benchmark scenarios in total profit by an average of 8.43 % in multi-day instances. Additionally, compared to the traditional node-based landing scenario, employing our en-route takeoff and landing strategy can save 0.9 h/(drone*day) of waiting time on average.

Analyses of sea turtle landing behavior based on frequently observed coastal profile data - A case study in Enshu Coast, Japan

This study analyses sea turtle landing behavior along a 10 km sandy beach on the Enshu Coast, Japan, facing the Pacific Ocean. Data for the analysis are sea turtles' landing positions and crawl tracks recorded by a handheld GNSS device from May to September (2011–2016), noting spawning or no-spawning activity simultaneously, supplemented by weekly cross-shore beach profiles surveyed at four locations, satellite images, and other geographical data. At the onset, landing positions on the beach are visualized to determine local concentrations along the beach. Subsequently, we estimate the distance of spawning and no-spawning positions from the waterline during landing and evaluate beach stability through the temporal elevation change standard deviation. The study found that preferred spawning locations are 40–70 m from the waterline, above the intertidal zone, on bare sand, with a standard deviation of 0.1–0.6 m. This study also highlights the impact of beach infrastructure on sea turtle spawning failures and the influence of significant wave height on sea turtle landing.

Mechanisms of speed-accuracy trade-off in tennis topspin forehand of college players

ABSTRACT This study aimed to elucidate the mechanisms underlying the speed-accuracy relationship in a tennis topspin single-handed forehand groundstroke. Groundstrokes at three different speeds by nine college players were captured, with the variability of the ball landing position evaluated as indices of accuracy. Variabilities of ball launch variables (speed, launch angle, spin, etc.) and conversion ratios from these variabilities to the variability of the ball landing position were quantified. These variabilities and their conversion ratios could be influenced by different efforts exerted to generate ball speeds and different ball trajectories required to hit a target at each speed, respectively. The speed-accuracy trade-off was observed only in the hitting direction. While the variability of the spin axis increased, it had minimal influence on the ball landing position. Conversely, the conversion ratio in the hitting direction of the velocity elevation angle significantly increased, while its variability remained unchanged. Consequently, the geometrical requirements of ball trajectories can be responsible for the speed-accuracy trade-off. Therefore, even skilled players capable of maintaining consistent ball launch variables regardless of the shot speed should deliberately choose a moderately slower ball speed to avoid an inevitable increase in the variability of the ball landing position due to geometrical requirements.

The Validity of Land Sale and Purchase in Depok City: A Case Study of the District Court Decision No. 87/Pdt.G/2018/Pn.Dpk

**The Sale and Purchase of Land According to Customary Law** refers to the transfer of rights, characterized by being *cash*, *real*, and *clear*. However, in practice, there are still instances where land sales do not fulfill the requirement of *clarity*, as in the case of District Court Decision No. 87/Pdt.G/2018/PN.Dpk. In this case, the land sale conducted between Agus Ariyanto and Sunaryo was not formalized through a deed before a Land Deed Official (PPAT), but was only evidenced by a receipt and a statement of sale and purchase. The issues raised are whether the land sale based only on a receipt constitutes a valid legal act, and whether the legal considerations and decision of the judge in case No. 87/Pdt.G/2018/PN.Dpk regarding the land sale, supported only by a receipt, align with Government Regulation No. 24 of 1997 on Land Registration. This research is a type of normative legal research and descriptive in nature. The data used are secondary data supported by primary data and analyzed qualitatively. The method of conclusion in this study employs deductive logic. Based on the results of the research, the sale and purchase of land between Agus Ariyanto (Buyer) and Sunaryo (Seller) can be considered valid under the provisions of the Civil Code (KUHPerdata) and meets the material requirements. However, the legal considerations and the judge's decision do not comply with the provisions of Government Regulation No. 37 of 1998 concerning the Regulations on the Position of Land Deed Officials.

Adjustment of segmental rotations to achieve both racket speed and accuracy at various impact heights during a two-handed backhand stroke

ABSTRACT This study investigated the influence of impact height and competitive level on racket speed and stroke accuracy by analysing segmental angular kinematics under a random ball condition. High- (HQ, n = 7) and low-quality (LQ, n = 7) groups were determined by k-means clustering of the ratio of ball landing in the target (accuracy) and racket speed decrease. HQ showed higher accuracy (48.3% vs. 32.4%), less speed decrease at lower impact heights (−4.4% vs. −10.3%) and better competitive level ranking [median (1st–3rd quartiles); 4 (2–7)] than LQ [10 (8–13)]. HQ produced greater racket speed (24.4 vs. 21.6 m/s), especially with a notable horizontal velocity (23.8 vs. 20.8 m/s) of the racket at lower impact height, which was attributed to the central role of greater angular velocity of pelvis and thorax in the hitting direction. Both groups showed similar adjustment mechanisms that due to the decrease in angular velocity of pelvis, players increased the relative rotation angle between pelvis and thorax to maintain angular velocity of thorax when transitioning from low to high impact heights. Our findings suggest that players should emphasise the coordination between pelvic and thoracic rotations according to impact heights to maintain racket speed while controlling ball landing position.

Reliability and validity of the fulltrack AI application to determine cricket bowling line and length compared to 3D motion capture

ABSTRACT This study examined reliability and validity of the Fulltrack AI application to identify cricket ball landing position (line, length). Nine hundred and thirty-two deliveries were compared to 3D motion capture, the criterion measure, with 836 included in analysis (516 bowled (pace = 420, spin = 96), 320 SidearmTM; 301 facing a batter). Agreement analysis indicated an intraclass correlation coefficient of >0.96 for raw and filter 3D line and length data, compared to Fulltrack AI. The coefficient of variation was acceptable for length (<10%) and larger for line (23.82%), albeit with a smaller standard error of measurement (SEM = 0.05 m), improving with outliers removed. Bland−Altman plots confirmed good statistical agreement between devices, with limits of agreement largely within maximal allowable difference values. There are potential practical application considerations, given SEM = 0.47 m for length (diameter of seven cricket balls); with greater variability detecting length closer to the batters-end, and line closer to the bowlers-end. Validity, using a generalised additive model, showed no significant differences between devices (p > 0.05), with no condition-based interaction effects. The Fulltrack AI application enables ecologically valid assessment of bowling performance. Considering the trade-off between this and the accuracy of information is warranted when deciding how best to apply it to coaching environments to support augmented feedback.

LIABILITY OF TEMPORARY LAND DEED OFFICIALS FOR NEGLIGENCE IN READING DEEDS DURING SALE AND PURCHASE TRANSACTIONS

Land Deed Officials (PPATs) play a crucial role in ensuring the legal certainty of the authentic deeds they prepare. Temporary PPATs share the same primary duties and authorities as regular PPATs and are required to comply with relevant regulations. The issue arises when a Temporary PPAT fails to read the authentic deed in front of the parties, leading to questions about responsibility and legal consequences. This research examines these concerns in light of Government Regulation Number 24 of 2016, which amends Government Regulation Number 37 of 1998 concerning the Position of Land Deed Officials. Employing a normative juridical research method, the research analyzes secondary data from legal materials, complemented by primary data gathered through interviews. The research is descriptive-analytical, using qualitative juridical data analysis. The findings reveal that a Temporary PPAT’s failure to read the authentic deed before the parties, as required by Article 22 of the Government Regulation on the Position of PPAT, results in the deed being classified as an underhand deed or null and void. This negligence has legal ramifications, including administrative, civil, and criminal liability. The Temporary PPAT can be held accountable if it is proven that their failure caused harm to the parties, leading to potential sanctions if the Temporary PPAT’s unlawful actions are substantiated.

Accurate model development for predicting sprinkler water distribution on undulating and mountainous terrain

The hilly terrain modifies the droplet landing positions in comparison to flat ground, complicating the prediction of sprinkler water distribution on such uneven regions. Utilizing a digital elevation model combined with droplet dynamics and evaporation models, droplet landing positions were calculated on both flat and uneven terrains. From the droplet landing positions and the corresponding water application rates on flat terrain, the water application rate on hilly terrains was deduced using the principle of water volume conservation. Subsequently, a software application was developed to assist in this prediction. Using the radial water distribution data from an individual sprinkler under various operating pressures and the elevation data of a hill, the software predicts the water distribution for either an individual sprinkler or an entire solid-set sprinkler irrigation system on the hill. This allows for the calculation of the average water application rate (h¯) and distribution uniformity (UCS) for combined sprinklers. The simulated water application rate on hilly terrains was validated using an experimental platform that replicates the sprinkler arrangement on a hill, devoid of plant canopy. Our findings indicate that the simulated water application rate for a sprinkler on hilly terrain aligns closely with the observed values, achieving a confidence coefficient (c) of 0.96. The developed software reliably predicts sprinkler water distribution on hilly terrains with significant accuracy for the conditions studied. We compared the UCS of the flat, hilly slope, and homogeneous slope terrains and found that the hilly slope better reflects the uneven water distribution owing to the undulating characteristics of the hilly terrain.

Dual-stage control method for continuous hopping on the surface of small celestial bodies

Surface movement exploration techniques are an important approach to further the understanding of small celestial bodies. Hopping movement is employed to take advantage of the weak gravitational field of small celestial bodies, facilitating long-distance mobility of the rover. The rover exhibits a strong attitude-orbit coupling characteristic during the hopping movement. Different contact attitudes contribute to the challenge of determining the rebound trajectory, rendering it difficult for the rover to maintain continuous movement towards the target position along the nominal trajectory. In this paper, a dual-stage control method for continuous surface hopping movement is developed, wherein the control is applied separately during the flight stage and the collision stage. During the flight stage, applying attitude control enables the rover to establish contact with the surface in a specific attitude, ensuring accuracy in movement direction and creating favorable conditions for the control process in the collision stage. The flywheel is controlled in the collision stage to correct the state change and energy loss due to the collision, enabling the rover to attain the desired hopping state. Considering the energy consumption of the rover, the minimum hopping velocity sequence and angular velocity sequence are designed based on the hopping angle and heading angle. The intricacies and uncertainties inherent in the surface environment of small celestial bodies pose challenges for the rover during hopping and flying. In response to the issue, a finite-time adaptive sliding-mode control law is devised. The control law facilitates the rapid adjustment of the rover to the target attitude in flight, demonstrating strong robustness. In addition, by integrating the changes in contact point velocity with the impulse contact model, the accuracy of the rover's rebound state updates is enhanced. Finally, a set of simulations is performed, and simulation results indicate that the dual-stage control method can achieve a final landing position error of less than 0.2 m for a continuously hopping. The finite-time adaptive sliding-mode control law can stabilize the rover's attitude within 10 s. Conducting 500 Monte Carlo simulations of the continuously hopping rover in three small celestial body surface simulation environments shows that the position endpoint error is within 0.3 m.

THE VALIDITY OF USING THE FULLTRACK AI APP TO DETERMINE CRICKET BOWLING LINE AND LENGTH COMPARED TO 3D MOTION CAPTURE

INTRODUCTION A bowler’s ability to manipulate line and length of a delivery is a key performance attribute in cricket. 3D-motion capture (3DMocap), the gold standard in quantifying ball trajectories1 lacks ecological validity2. Fulltrack AI app may provide a feasible alternative to quantify and provide immediate ball trajectory feedback. This study explored the validity of Fulltrack AI to measure ball landing position compared with 3DMocap. METHODS 836 deliveries under various conditions (pace, spin; bowled, thrown (SidearmTM); batter, no batter), were recorded using a Qualisys 8-camera 3DMocap system and iPad running Fulltrack AI (version 1.13.1). Line and length were extracted from Quintic Spline filtered 3DMocap data and tabulated with Fulltrack AI data. Statistical analyses were conducted in R Statistical Software following removal of outliers. Bland Altman’s, 95% limits of agreement (LOA)3 were calculated, with line and length interaction further explored using 95% confidence ellipse area (CEA) to assess practical difference between 3DMocap and Fulltrack AI relative to ball landing position. Validity between Fulltrack AI and 3DMocap, and the interaction of conditions, were assessed with generalised additive models (GAMs). RESULTS Whilst LOA (line= -0.15 to 0.10; length= -0.88 to 0.27) demonstrated good agreement, CEA ranged from 0.17m2 to 0.42m2 depending on ball landing location relative to the stumps (2-4m or &amp;gt;8m, respectively). GAMs ‘average model’ established no significant (p&amp;gt;0.05) difference between 3DMocap and Fulltrack AI, or the interaction effects of training conditions. CONCLUSION Although Fulltrack AI appears statistically and ecologically valid in identifying cricket ball landing position, practitioners should be cognisant that practically, error varies relative to where on the wicket a ball lands. Thus, hindering the accuracy of feedback if needing to precisely quantify ball landing position when using Fulltrack AI app.

Effects of Land uses on Soils Quality in Rwandan Central Plateau Agro-Ecological Zone

Conversion of land use from forest to agricultural uses modifies soil quality through physiochemical soil properties changes. This study was conducted in Rwanda’s central plateau agro-ecological zone to evaluate the effect of forest and agricultural land uses on soil quality. The study was conducted in 2020. Soil samples were collected at the top, middle and bottom positions of each of the two land uses. We analyzed soil bulk density, soil moisture content, soil pH, soil organic matter (SOM), total nitrogen (TN), available phosphorus (Av P), and CEC for each position of the land uses. Data were analyzed using ANOVA in GENSTAT version 13. The results revealed that soil properties were significantly affected by land use change. Analysis of variances (LSD&lt;0.05) results showed, however, that treatments were not significantly different within the same land use. The results showed that treatments from top position of forest lands had the highest mean values for soil organic matter and total N parameters with the respective mean values of 6.58 %, and 0.37 %. Treatments from middle position of forest lands had the highest mean values for soil moisture content and Av P parameters respectively with 23.60 % and 29.56 ppm. But, soil bulk density was high on top position of agricultural land with a mean value of 1.49 g/cm3. Land users are advised to apply crop and soil management techniques which maintain soil quality and productivity on agricultural lands.

The Position of Ulayat Rights in Land Provision in the Implementation of National Development Viewed from the Perspective of Positive Law and Islamic Law

Customary rights often face problems when connected with national development due to the legal status of customary land. In connection this matter, research is needed in order to understand the position of customary land in relation to national development. of customary land when it is connected with national development. In order to to examine this, the research in this case uses normative juridical research because an in-depth understanding is needed with regard to regulations that discuss regarding customary rights. The result of this research is the position of of customary rights in land acquisition in the context of national development is still very weak, which is due to the absence of regulation on customary rights. very weak, which is due to the absence of a more detailed regulation of customary rights. so that the customary rights community lacks supporting evidence and legality to obtain compensation. supporting evidence and legality to obtain compensation for the utilisation of customary rights for national development. for national development.

Lingering on distraction: Examining distractor rejection in adults with ADHD

ABSTRACT Effective visual search relies on reactively disengaging from distractors when the features of the distractors are unpredictable. Does this ability differ between adults with and without Attention-Deficit/Hyperactivity Disorder (ADHD)?. Participants (36 with ADHD, 46 non-ADHD) completed the additional-singleton task, in which they searched for a unique shape while a uniquely coloured distractor unpredictably appeared on half of the trials. The distractor delayed manual response times in both groups, with no significant group difference. Both groups also demonstrated similar oculomotor capture effects, as indicated by the landing position of initial fixations. However, when initial fixations did land on the distractor, participants with ADHD tended to “linger” on the distractor with additional fixations and longer duration before disengaging from it, compared to those without ADHD. These results suggest that ADHD is associated with deficits in reactively disengaging from distractions rather than deficits in avoiding being captured in the first place.

LAND AS THE SOUL OF THE NATION: IMPLICATIONS OF THE TRANSITION OF LAND STATUS IN THE TALANG MAMAK CUSTOMARY LAW COMMUNITY

The land reflects the identity and spirit of the nation that are ingrained in the life of the Talang Mamak indigenous community, in addition to serving as an economic resource. Change in land status has several implications for their relationship with the land and its management. The purpose of this study is to examine the position of land for the Talang Mamak indigenous people. In addition, it analyses the implications of changing the status of land from customary forest to national park forest. This qualitative study employs the sociological law research approach by looking into the legal facts of the indigenous society of Talang Mamak in light of their relationship, ownership, and management of land. The main finding of this study is that the value of that land, due to its significant meaning and position, cannot be isolated from the Talang Mamak indigenous people. Nevertheless, the change in land status has created gaps and limited rights in forest management, highlighting several implications for the identity of the Talang Mamak indigenous people.

Mechanism for High-Precision Control of Movement at Maximum Output in the Vertical Jump Task.

Human movements are governed by a tradeoff between speed and accuracy. Previous studies that have investigated the tradeoff relationship in sports movements involving whole-body movements have been limited to examining the relationship from the perspective of competition-specific movements, and the findings on whether the relationship is valid have not been unified. Therefore, this study incorporated a vertical jump task with the introduction of a condition in which landing position control was added to evaluate the essence of a sports movement that requires both speed and accuracy. Accuracy was examined using a method that quantifies the coordinates of the landing and takeoff positions using entropy. The mechanism of that tradeoff was then examined by confirming the phenomenon and analyzing the 3D vector trajectories. An increase in accuracy and a decrease in speed were observed when the landing position was the control target, even in the vertical jumping task normally performed at maximum effort, and the 3D velocity vector was characterized by the following: a reduced scalar and a more vertical direction. While the entropy from the takeoff to the landing position seemed to decrease when the accuracy of the landing position improved, the following noteworthy results were obtained given the characteristics of the vertical jump. Unlike traditional feedback control in the entropy reduction in hand movements, the trajectory is predetermined in a feedforward-like manner by controlling the initial velocity vector at takeoff, which allows the landing point to be adjusted.

Saccades to partially occluded objects: Perceptual completion mediates oculomotor control.

Oculomotor behavior typically consists of directing gaze to objects in complex scenes for the purpose of extracting detailed perceptual information. Here, we probed the nature of the visual representations over which saccades to objects are computed. We contrasted an image-based oculomotor control hypothesis, holding that saccades are computed solely over information explicit in the retinal image, and an object-based oculomotor control hypothesis, holding that saccades are computed over object representations reflecting the three-dimensional structure of the scene. We recorded saccade landing positions to partially occluded objects in a naturalistic search task. In Experiment 1, saccade landing positions were biased toward the center of the perceptually completed object. Experiment 2 demonstrated that the bias held even when it would have been strategically advantageous to avoid it. Experiment 3 demonstrated that the bias was not due to image-level differences generated by the presence of occluders. The results indicate that saccade motor programs are computed, at least in part, over object-level representations reflecting the completion of occluded surfaces.

Quantitative comparison of ocean soundscape model and measurements in the Atlantic outer continental shelf

For 4 years, the Atlantic Deep Water Ecosystem Observing Network (ADEON), measured the acoustic soundscape using 7 bottom mounted landers off the coast of the South East United States (from Florida to Virginia). A shipping and noise model was built to generate regional sound maps, as well as to perform site-specific modeling for frequencies ranging from 20 Hz to 3150 Hz. The regional sound maps reveal that water depth is the key driver to local sound levels followed by the local geo-acoustic properties. It is predicted that the sound can be as much as 10 dB higher on the seafloor than at depths of 10 m. The site specific (where landers were deployed) model was run with a wide range of sediment uncertainty in the model, given our lack of knowledge of the sediment structure in water depths of 200 to 800 m deep, far from shore. A simple qualitative comparison of the soundscape measurements with the model provides immediate insight into the type of sediment at each lander position. Using this estimated sediment type, quantitative comparisons between the model and the data are made.

Monsoon Planet: Bimodal Rainfall Distribution due to Barrier Structure in Pressure Fields

Abstract Monsoon systems transport water and energy across the globe, making them a central component of the global circulation system. Changes in different forcing parameters have the potential to fundamentally change the monsoon characteristics as indicated in various paleoclimatic records. Here, we use the Atmosphere Model developed at the Geophysical Fluid Dynamics Laboratory (GFDL-AM2) and couple it with a slab ocean in order to analyze the monsoon’s sensitivity to changes in different parameters on a planet with idealized topography (varying land position, slab depth, atmospheric CO2 concentration, solar radiation, sulfate aerosol concentration, and surface albedo). This Monsoon Planet concept of an aquaplanet with a broad zonal land stripe allows us to reduce the influence of topography and to access the relevant meridional monsoon dynamics. In simulations with monsoon dynamics, a bimodal rainfall distribution develops during the monsoon months with one maximum over the tropical ocean and the other one over land. The intensity and extent of the monsoon depend on the relative height of a local maximum in the surface pressure field that is acting as a barrier and is determining the coastward moisture transport. Changes in the barrier height occur during the course of one year but can also be induced when varying different parameters in the sensitivity analysis (e.g., the increase of atmospheric CO2 reduces the barrier height, resulting in an increase of rainfall, while aerosols have the opposing effect). This bimodal rainfall structure separated by a pressure barrier is also present in reanalysis data of the West African monsoon. Significance Statement Monsoon rainfall directly impacts the livelihood of millions of individuals in the tropics. Because monsoons transport energy and water around the globe, their influence reaches far beyond the tropics, and changes in their dynamics affect the climate both locally and globally. The individual monsoon systems are subject to various forcing factors that determine the monsoon characteristics in partly opposing ways. Here, we implement a model setup of the Monsoon Planet to study the monsoon’s sensitivity to various forcings in a simplified design, allowing us to gain new insights into monsoon dynamics. We find that a local maximum in the pressure field is acting as a barrier for moisture transport and thus determines the monsoon characteristics over land.