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Path Planning methods for the autonomous control of Unmanned Aerial Vehicle (UAV) swarms are on the rise due to the numerous advantages they bring. There are increasingly more scenarios where autonomous control of multiple UAVs is required. Most of these scenarios involve a large number of obstacles, such as power lines or trees. Despite these challenges, there are also several advantages; if all UAVs can operate autonomously, personnel expenses can be reduced. Additionally, if their flight paths are optimized, energy consumption is reduced, leaving more battery time for other operations. In this paper, a Reinforcement Learning-based system is proposed to solve this problem in environments with obstacles by utilizing Q-Learning. This method allows a model, in this case, an Artificial Neural Network, to self-adjust by learning from its mistakes and successes. Regardless of the map's size or the number of UAVs in the swarm, the goal of these paths is to ensure complete coverage of an area with fixed obstacles for tasks like field prospecting. Setting goals or having any prior information apart from the provided map is not required. During the experimentation phase, five maps of varying sizes were used, each with different obstacles and a varying number of UAVs. To evaluate the quality of the results, the number of actions taken by each UAV to complete the task in each experiment was considered. The results indicate that the system achieves solutions with fewer movements as the number of UAVs increases. An increasing number of UAVs on a map lead to solutions in fewer moves. The results have been compared, and a statistical significance analysis has been conducted on the proposed model's outcomes, demonstrating its capabilities. Thus, it is shown that a two-layer Artificial Neural Network used to implement a Q-Learning algorithm is sufficient to operate on maps with obstacles. • Q-Learning for UAV swarm to determine the best flight path to cover the most area. • Estimate the flight paths on any size map with obstacles and without map information. • A system capable of calculating paths without the need for a smoothing stage. • Statistical comparison of a single ANN for each UAV against a global ANN for all UAVs. • An aircraI architecture-independent path optimization criterion. [ABSTRACT FROM AUTHOR]

The present study investigated the adaptations of specific power bursts during the combined contexts of the proximity (lead vs. trail limb) and height of an obstruction in relation to limb elevation versus progression. Ten young, adult, male subjects walked at their natural speed during unobstructed walking and the bilateral avoidance of moderate and high obstacles. Hip flexor generation power was unaffected by obstacle height for the leading limb and always delayed for the trailing limb. The knee extensor absorption power burst at toe-off was also eliminated for the trailing limb and was found to reappear in mid-swing. Few differences were seen for ankle push-off power. The results suggest that the hip joint is dedicated to limb advancement only, while the knee joint is directly involved in limb elevation and the control of multiarticular effects. [ABSTRACT FROM AUTHOR]

Magnetic resonant wireless power transmission (MRWPT) is a method of transmitting power over a long distance at a specific frequency. Because this system uses an alternating magnetic field, if an object with electrical/magnetic properties is placed between the transmit and receive coils, this will have a significant impact on the power transfer. In this paper, the effect of an obstacle located between two coils on the resonance frequency and transmission power is analyzed. A wireless power transmission system with a resonant frequency of 20 kHz was designed, and ferrite, aluminum, and carbon steel were selected as obstacles with permeability or conductivity. After simulating the system with finite element analysis (FEA) with these obstacles, the results were verified through actual experiments. The results show that the permeability of the obstacle decreases the resonant frequency, and the conductivity increases the resonant frequency and greatly reduces the output power. In addition, part of reduced output could be recovered by adjusting the frequency.

Introduction Stereo vision means the capability of extracting the depth based on analysis of two images taken from different angles of one scene. The result of stereo vision is a collection of three-dimensional points which describes the details of scene proportional to the resolution of the obtained images. Vehicle automatic steering and crop growth monitoring are two important operations in agricultural precision. The essential aspects of an automated steering are position and orientation of the agricultural equipment in relation to crop row, detection of obstacles and design of path planning between the crop rows. The developed map can provide this information in the real time. Machine vision has the capabilities to perform these tasks in order to execute some operations such as cultivation, spraying and harvesting. In greenhouse environment, it is possible to develop a map and perform an automatic control by detecting and localizing the cultivation platforms as the main moving obstacle. The current work was performed to meet a method based on the stereo vision for detecting and localizing platforms, and then, providing a two-dimensional map for cultivation platforms in the greenhouse environment. Materials and Methods In this research, two webcams, made by Microsoft Corporation with the resolution of 960×544, are connected to the computer via USB2 in order to produce a stereo parallel camera. Due to the structure of cultivation platforms, the number of points in the point cloud will be decreased by extracting the only upper and lower edges of the platform. The proposed method in this work aims at extracting the edges based on depth discontinuous features in the region of platform edge. By getting the disparity image of the platform edges from the rectified stereo images and translating its data to 3D-space, the point cloud model of the environments is constructed. Then by projecting the points to XZ plane and putting local maps together based on the visual odometry, global map of the environment is constructed. To evaluate the accuracy of the obtained algorithm in estimation of the position of the corners, Euclidian distances of coordinates of the corners achieved by Leica Total Station and coordinates and resulted from local maps, were computed. Results and Discussion Results showed that the lower edges have been detected with better accuracy than the upper ones. Upper edges were not desirably extracted because of being close to the pots. In contrast, due to the distance between lower edge and the ground surface, lower edges were extracted with a higher quality. Since the upper and lower edges of the platform are in the same direction, the lower edges of the platform have been only used for producing an integrated map of the greenhouse environment. The total length of the edge of the cultivation platforms was 106.6 meter, that 94.79% of which, was detected by the proposed algorithm. Some regions of the edge of the platforms were not detected, since they were not located in the view angle of the stereo camera. By the proposed algorithm, 83.33% of cultivation platforms’ corners, were detected with the average error of 0.07309 meter and mean squared error of 0.0076. Non- detected corners are due the fact that they were not located in the camera view angle. The maximum and minimum errors in the localization, according to the Euclidian distance, were 0.169 and 0.0001 meters, respectively. Conclusions Stereo vision is the perception of the depth of 3D with the disparity of the two images. In navigation, stereo vision is used for localizing the obstacles of movement. Cultivation platforms are the main obstacle of movement in greenhouses. Therefore, it is possible to design an integrated map of greenhouse environment and perform automatic control by localization of the cultivation platforms. In this research, the depth discontinuity feature in the locations of the edges, was used for the localization of the cultivation platforms’ edges. Using this feature, the size of the points required for establishing the point cloud model and also the associated processing time decreased, resulting improvement in the accuracy of determining coordination of the platforms’ corners.

The potential of tourism in West Sumatra continues to squirm. By having natural attractions (Lake, Valley, Mountains, Coast, Sea) also has a wide range of cultures that accompanied the various attractions and specific local knowledge. However, with the myriad of potentials and with a number of marketing strategies that have been carried out, West Sumatra tourism to flourish and far behind other regions such as Bali, Yogyakarta, Bandung, even North Sumatra. Of course there are obstacles in the development of tourism. To that end, in addition to reviewing the aspects that become obstacles for tourism development of West Sumatra, more concretely also examined aspects of the constraints in the tourist area of Lake Above and Below Lake which is one of the attractions in West Sumatra. This study used mixed methods (Mixed Method) with sequential exploratory strategy. The analytical method used is the Delphi method which is supported by the identification of constraints through the mass media, deskirptif analysis of qualitative and descriptive statistical analysis. The study shows that the main obstacle aspects of tourism development of West Sumatra is the mindset aspect of society, aspects of planning, financing support aspect. Another aspect is the economic society, marketing and infrastructure support. In contrast to the constraints of development of tourist areas of Lake Above and Below Lake, the results showed the obstacles in the form of people who think that mindset, tourism is less promising as a source of income, while the farm will get pengasilan great. The different thing is revealed when analyzing public perception of the response. It turned out that people do not know what exactly are the benefits of tourism, the public does not know which part they should play an active role, which means that people do not know its position in the tourism sector.

Turbidity currents are the main process for the transport and deposit of sediments in reservoir, especially in the deepest part near the dam, where vital structures such as power intakes and bottom outlets are located. The existence of an obstacle in such current can cause a decrease in the velocity and thickness of the second turbidity current which, occurs after the obstacle. In this study that was carried out as a two-dimensional experimental study, the effect of a solid obstacle, its height on the vertical distribution profiles of the velocity, when there is an abrupt decreasing in the bottom slope, was investigated. Separate non-dimensional equations for the vertical distribution of velocity in different cases were developed. The coefficient of the non-dimensional equations were compared with each other. Results indicated that the existence of an obstacle can reduce the velocity of the turbidity current, which passes the obstacle, about 20%-50%, and also can reduce the discharge of the current by increasing the relative height of the obstacle from 0.0091 to 0.273 by about 20% -60%, respectively. This effect on turbidity current’s velocity and discharge would be increased by the increasing the height of the obstacle. The results also indicate that the highest change in the current discharge occurred in the jet region of the velocity profile.

The importance of navigation support for people with disability has been demonstrated by convention on the Rights of Persons with Disabilities. This paper presents the navigation infrastructure for people with disabilities. The infrastructure includes map generation service, web interface, mobile services. Also we purpose method of target area examination by volunteers. Using a modified Openstreetmap road graph allows you to build more precise routes. Introduced classification of obstacles types allows you to identify problems in the path of a person with disabilities. Application of Dijkstra's-based algorithm with modified edge weights allows you to find safe traffic routes. The results of testing on the pilot region allow us to estimate the amount of work required to improve the quality of people's live with disabilities.

Background: Web-based learning has transformed education. Its ability to overcome physical barriers and deliver knowledge at the click of a button has made web-based learning popular and ensured that it will continue to be used in the future. The involvement of parents in web-based learning is fundamental to the success of the educational process, but limited attention has been paid to the impact of web-based learning on parents., Objective: This study examined parental experiences with school-aged children receiving web-based learning in Jeddah, Saudi Arabia., Methods: We sent cross-sectional, anonymous web-based questionnaires to school-aged children's parents. A total of 184 parents completed the survey., Results: Parents' negative experiences of web-based learning (mean 4.13, SD 0.62) exceeded their positive experiences (mean 3.52, SD 0.65). The most negative experience reported by parents was their child's boredom due to prolonged sitting in front of a device (mean 4.56, SD 0.69). The most positive experience was their child's technological skill enhancement (mean 3.98, SD 88). Their child's lack of social interaction and friendship building promoted stress among parents (r=-0.190; P=.01). At the same time, their child's technological skill enhancement reduced stress among parents (r=0.261; P=.001). The most reported (63/184, 34.2%) obstacle to web-based learning was having multiple learners in the same household., Conclusions: Web-based learning is a fundamental learning method and will continue to be used in the future because of its ability to overcome many barriers to education. Parental involvement in the continuity and success of the web-based learning process is crucial. However, the findings of this study illustrated that parents' experiences of web-based learning were more negative than positive. Parents who reported negative experiences reported an increase in stress and faced more obstacles due to web-based learning. Thus, more attention and intervention are needed to promote positive web-based learning experiences among parents., (© Samaa Al Anazi, Eman Bajamal, Neama Hantira, Ola Esheaba. Originally published in JMIR Pediatrics and Parenting (https://pediatrics.jmir.org).)

La présente étude visait à documenter l'implantation de l'Accompagnement-citoyen personnalisé d'intégration communautaire (APIC), lors duquel des bénévoles soutiennent la participation sociale d'aînés, dans des organismes communautaires en identifiant les facteurs favorables et défavorables ainsi que ses conditions essentielles. Soutenu par un devis qualitatif descriptif de type recherche clinique, une rencontre et six entretiens semi-dirigés ont été réalisés afin de documenter cette implantation dans six organismes communautaires œuvrant en milieu urbain au Québec (Canada). Selon les six coordonnatrices de l'APIC, les cinq directeurs généraux et l'agente de recherche, le principal facteur favorable est la conviction des responsables de l'implantation en la valeur ajoutée de l'intervention, incluant sa concordance avec la mission et les valeurs des organismes et les besoins de la population qu'ils desservent. Les facteurs défavorables sont principalement la répartition aléatoire et le temps accordé pour l'implantation. Ces résultats permettront de mieux guider l'implantation de l'APIC à plus grande échelle.

Within the last decade, a number of crowd accidents have attracted the interest of scientists to study the movement of crowd under high levels of competition. An interesting finding in crowd dynamics is that the presence of an obstacle at an appropriate distance in front of an exit can improve flow rate. A numerical simulation based on the discrete element method (DEM) and social force model was adopted in this paper in order to study the impact of obstacles on flow rate during competitive evacuation in two typical Settings with a single 0.8 m-wide exit. Setting I is a 15 m-wide room and Setting II is a 3 m wide corridor formed by the same room with lateral constrains. Numerical simulation in Setting I showed that a 1 m-obstacle at 1-m away from the exit can reduce evacuation time by approximately 49%. However, a contrasting increase of evacuation time by approximately 64% is observed in Setting II for the obstacle at the same location. To verify the findings, a number of experiments were conducted by compelling mice to escape under high competition in two similar settings. The general limitations of such experiments were accepted and described. These results were consistent with numerical simulations. This study demonstrates that whether an obstacle can improve the flow rate passing through an exit is dependent on the surrounding geometry. [ABSTRACT FROM AUTHOR]

The combustible and explosive characteristics of corn starch dust pose a significant safety risk in its production and processing. To reveal the influence of obstacle opening sizes on the flame propagation characteristics, a self-designed vertical experimental platform of a dust combustion pipeline was implemented. Specifically, the flame temperature and pressure changes in the pipeline were collected by micro-thermocouples and pressure sensors, and dust flame images under different conditions were recorded by a high-speed photography system. The results demonstrate that, after being set in the pipeline, the obstacle destroys the flame structure and causes the flame to exist in a strong turbulent and irregular state. Meanwhile, owing to the blocking of the obstacle, the flame may disappear under certain conditions and brightness is reduced. The obstacles have an incentive effect on the flame temperature, and the obstacle opening size is inversely proportional to the peak temperature of the corn dust flame. With an increasing obstacle opening size, the combustion pressure first increases and then decreases. At an opening size of 50 × 50 mm2, the combustion pressure reaches its highest value. Although the obstacles exert an incentive increase on the combustion pressure wave at large opening sizes, obstacles with a sufficiently small opening size significantly inhibit the pressure wave propagation. [ABSTRACT FROM AUTHOR]

The proposed study presents an original concept for the design of a walking robot with a minimum number of motors. The robot has a simple design and control system, successfully moves by walking, avoids or overcomes obstacles using only two independently controlled motors. Described are basic geometric and kinematic dependencies related to its movement. It is proposed optimization of basic dimensions of the robot in order to reduce energy losses when moving on flat terrain. Developed and produced is a 3-D printed prototype of the robot. Simulation and experiments for overcoming an obstacle are presented. Trajectories and instantaneous velocities centers of links from the robot are experimentally determined. The phases of walking and the stages of overcoming an obstacle are described. The theoretical and experimental results are compared. The suggested dimensional optimization approaches to reduce energy loss and experimental determination of the instant center of rotation are also applicable to other walking robots. [ABSTRACT FROM AUTHOR]

A steady laminar two-dimensional magneto-hydrodynamics mixed convection flow in a square inclined cavity filled with Cu–water nanofluid is investigated numerically by using the finite difference method. The left and right vertical sidewalls of the cavity are considered adiabatic and move upward, while a partial slip flow condition is imposed on these walls. The horizontal top wall is considered cold and stationary, while a part of the stationary bottom wall is subjected to a uniform heat source and the remaining parts of it are considered adiabatic. An adiabatic obstacle is located in the center of the cavity and an external magnetic field is applied parallel to the horizontal x-axis. Parametric studies of the influence of various parameters such as Hartmann number, inclination angle of the cavity, dimensionless heat generation/absorption coefficient, obstacle aspect ratio, dimensionless length and location of the heat source, and solid volume fraction on the fluid flow and heat transfer have been performed. Comparisons with previously published numerical work are performed, and good agreements between the results are observed. It is found that the nanofluid was better than water to enhance the heat transfer when the effect of the magnetic field is weak, while the water is better than the nanofluid when its effect is strong. Moreover, the results indicated that the partial slip has a significant effect on the above-mentioned parameters. [ABSTRACT FROM AUTHOR]

In this study, the mixing performance and pressure drop characteristics have been numerically analyzed for flow through rectangular microchannel with obstacles in the walls arranged in a staggered manner. Three different aspect ratios (AR) of the obstacles are considered, namely 4:1, 1:1, and 1:4. The effects of aspect ratio of the obstacles on the mixing efficiency and the pressure drop are analyzed and compared with that of the channel without obstacle. The results are presented in terms of Reynolds number (Re) and Schmidt number (Sc) in the following range: 0.2 ≤ Re ≤ 1 and 500 ≤ Sc ≤ 1500. Enhanced mixing efficiency is achieved for the case of microchannel with obstacles and the corresponding pressure drop is also found to be higher. The mixing efficiency as well as the pressure drop is maximum for AR = 1:4 among all the geometries considered in the analysis in same flow condition. Furthermore, for a given configuration of the microchannel the mixing efficiency is governed by the mass Peclet number and, accordingly, the mixing efficiency increases with the decrease in Schmidt number for a given Reynolds number. [ABSTRACT FROM AUTHOR]

• The experiments by using various obstacles submerged in the liquid-metal film-flow were conducted in the range of Re = 487–1583 and N=0–149. • With increasing the strength of magnetic field, heat flux increased and peak heat flux location moved toward the upstream of test section. • Efficiency of heat transport increased suddenly at lower N region and saturated at higher N. • The surface temperature without any obstacle showed the highest. • It was concluded that thermal mixing performance of the delta-wing is higher than the cubic, hemisphere and plane. Heat removal techniques of various liquid divertor concepts have been widely studied. In this study, thermal mixing characteristics of the liquid metal film-flow with locally heated on the surface under the vertical magnetic field were experimentally investigated by using various types of obstacles as a vortex generator. Especially, the efficiency of heat transport was investigated by the thermocouples installed on the bottom-wall. The velocity distributions were measured using the electric potential probe rake on the downstream of the channel. A delta-wing, a hemisphere or a cubic obstacle was used as a vortex generator installed at the center of the bottom-wall. The experiments were conducted for laminar flow region where Re = 487–1583 and in the range of N (=Ha2/Re) = 0–149 in the vertical magnetic field in the acrylic rectangular duct. GaInSn alloy was used as a working fluid. According to the comparison of heat flux distributions on the bottom-wall, the entire distributions moved towards the upstream with increasing of the strength of the vertical magnetic field for all cases. This tendency means the heat removal from the free-surface of liquid metal film-flow to the bottom-wall can be shortly achieved in case of the relatively high vertical magnetic field. [ABSTRACT FROM AUTHOR]

The span-wise obstacle on the suction surface of a hydrofoil has been verified to be an effective passive control method for cloud cavitation. The position of obstacle significantly influences the performance of cavitation control. In this research, we investigated the effect of obstacle position on attached cavitation control on the suction surface of a NACA0015 hydrofoil through response surface methodology. The cavitation types covered from sheet cavitation to partial and transitional cavity oscillations. We derived regression equations and built response surfaces to illustrate the quantitative relationship between individual factors (obstacle position, cavitation number, and angle of attack) and cavitation dynamic response parameters (cavity length, acoustic intensity, and energy flux). Sheet cavitation was effectively suppressed because the obstacle increased the pressure at the near-wall region. However, the obstacle would induce a shear cavitation when its position was too close to the leading edge of the hydrofoil. Under partial cavity oscillation conditions, the obstacle was consistently performed well in cloud cavitation control. The cavitation dynamic response parameters significantly decreased. Under transitional cavity oscillation conditions, the obstacle cannot suppress the cavitation because the transitional cavity oscillation was likely a system-inherent instability. This research is beneficial for a comprehensive understanding of cavitation control mechanism using an obstacle and for further industrial application of obstacle in hydraulic machinery to control cavitation. [ABSTRACT FROM AUTHOR]

Background: Asymmetrical load-carrying while walking requires modifications in joint forces to compensate the extra mass and ensure body stability, particularly when the environment is uneven, such as with a curb. Carrying a bag with one hand (dominant or non-dominant) may constrain the movement of the arm, altering the interlimb coordination of the upper limbs. Prior studies did not show changes in interlimb coordination when a light load was attached to the wrist, but the use of a bag to carry the load can be potentially disturbing since exaggerated movements of the bags may compromise balance. In this case, changes in interlimb coordination would be expected to minimize bag movements. However, it is not clear if these changes in interlimb coordination would be sufficient to affect the curb negotiation task.Research Question: We investigated the effect of asymmetric load-carrying using different bag types with the dominant and non-dominant hands on upper limb coordination and walking adaptations in a curb negotiation task in young adults.Methods: Seventeen young adults walked and stepped down a curb while carrying a bag with 7% of their body mass. The experimental conditions were to walk without the bag, carrying the bag (with and without strap) using the dominant and non-dominant hand.Results: Carrying the bag reduced the anti-phase pattern and increased the right or left shoulder phases, depending on the side used to carry the bag. It means that the limb that carried the load almost did not move while stepping down the curb. Load transportation did not influence foot-curb negotiation variables.Significance: Our study indicates that a mild load and the bag influenced the interlimb coordination of the upper limbs. Despite that, young adults compensated for the disturbance caused by the load carriage and did not compromise the curb negotiation task. [ABSTRACT FROM AUTHOR]

Background: In ambulatory stroke survivors, outdoor walking is important for participation, so adapting to heightened levels (e.g. curbs) is essential. This needs precise step regulation and foot positioning and has to be achieved despite impaired balance and motor regulation.Research Question: How do stroke patients approach and cross elevated surfaces?Methods: Gait of 12 hemiparetic stroke patients (62.8 ± 10.3 years; Functional Ambulatory Category 3-5) and 13 controls (60.0 ± 12.4 years) was compared using a sensor carpet and 3D motion capturing to collect tempo-spatial parameters and foot trajectories in two conditions: flat walking vs. approaching to and stepping onto an elevated surface (height 15 cm) in a self-selected manner (6 trials each). Tempo-spatial adaptations were normalized to flat walking while trajectory analysis focused on foot clearance and placement. Complementary assessments included the Dynamic-Gait-Index, the Berg-Balance-Test and the Falls Efficacy Scale.Results: Patients showed significantly worse Dynamic-Gait-Indices, less balance and more fear of falling. During the approach phase, patients slowed down, partly accompanied by shorter steps which controls did not. During crossing, no preference for a specific leading leg was detected. Clearance of the leading leg on average was not reduced but patients landed closer to the edge. Still clearance of the paretic leg was less than that of the non-paretic leg and the minimal clearance across all trials suggested an increased tripping risk, most evident for the trailing leg. In particular slower approaching caused difficulties to ensure sufficient leg clearance and to place the foot safely. Independent from that, better balance correlated with safer clearance.Significance: When managing elevated levels, leading with the paretic leg causes more difficulties to safely clear the legs which is considerably dependent upon speed. Therapists should consider that slow walking may not increase safety while faster gait and aspects of postural control potentially facilitate crossing a curb. [ABSTRACT FROM AUTHOR]

• The maximum overpressure increased when more obstacles were added. • Low and high frequency spectra of vessel vibration were observed. • A close relation between the pressure oscillation and vessel vibration was found. Experiments were conducted in a 1-m3 rectangular vessel with a 700 mm × 400 mm top vent to investigate the effects of cylinders placed parallel to the venting direction on vented hydrogen-air deflagrations and the structural response of the vessel wall to an explosion. Three pressure peaks, which corresponded to the opening of the vent cover, venting of the burnt gas mixtures, and the occurrence of the external explosion, respectively, were observed. The pressure peak corresponding to the external explosion always dominated the pressure-time histories, and the maximum internal overpressure was reached at the bottom of the vessel. The presence of cylinders in the vessel affected the explosion venting significantly. When more cylinders were placed, the maximum internal and external overpressure increased, whereas the amplitude of pressure oscillation and the time needed to reach the maximum overpressure decreased. A close relation between the pressure oscillation and vessel vibration was found. Low and high dominant frequency spectra of vessel vibration were observed in all tests. The former resulted from the acoustic oscillation of the internal pressure, and the latter corresponded to the resonance of the vessel, which may react against the flame and result in pressure oscillation with a frequency comparable with the natural frequency of the vessel. [ABSTRACT FROM AUTHOR]