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Traumatic brain injury is a leading cause of death and disability in the United States. Limited access to specialized medical and rehabilitation services has been linked to poor outcomes. Literature provides little guidance for as...
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Traumatic brain injury is a leading cause of death and disability in the United States. Limited access to specialized medical and rehabilitation services has been linked to poor outcomes. Literature provides little guidance for assessment of service obstacles and satisfaction with community resources. The present investigation describes the development of a specialized scale to evaluate caregivers' perceptions of brain injury services in the community. Results indicate good internal consistency and criterion-related validity of the Service Obstacles Scale. Lack of money for services and lack of adequate community resources were the greatest concerns voiced by respondents, while lack of transportation was the least problematic. Comparisons are made with regard to family needs and respondents' post-injury life quality. Implications for future research are discussed.
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An obstacle representation of a graph is a mapping of the vertices onto points in the plane and a set of connected regions of the plane (called obstacles) such that the straight-line segment connecting the points corresponding to ...
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An obstacle representation of a graph is a mapping of the vertices onto points in the plane and a set of connected regions of the plane (called obstacles) such that the straight-line segment connecting the points corresponding to two vertices does not intersect any obstacles if and only if the vertices are adjacent in the graph. The obstacle representation and its plane variant (in which the resulting representation is a plane straight-line embedding of the graph) have been extensively studied with the main objective of minimizing the number of obstacles. Recently, Biedl and Mehrabi [Therese C. Biedl and Saeed Mehrabi, 2017] studied non-blocking grid obstacle representations of graphs in which the vertices of the graph are mapped onto points in the plane while the straight-line segments representing the adjacency between the vertices is replaced by the L_1 (Manhattan) shortest paths in the plane that avoid obstacles.In this paper, we introduce the notion of geodesic obstacle representations of graphs with the main goal of providing a generalized model, which comes naturally when viewing line segments as shortest paths in the Euclidean plane. To this end, we extend the definition of obstacle representation by allowing some obstacles-avoiding shortest path between the corresponding points in the underlying metric space whenever the vertices are adjacent in the graph. We consider both general and plane variants of geodesic obstacle representations (in a similar sense to obstacle representations) under any polyhedral distance function in R^d as well as shortest path distances in graphs. Our results generalize and unify the notions of obstacle representations, plane obstacle representations and grid obstacle representations, leading to a number of questions on such representations.
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This paper is concerned with an inverse obstacle problem which employs the dynamical scattering data of an acoustic wave over a finite time interval. The unknown obstacle is assumed to be a sound-soft one. The governing equation o...
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This paper is concerned with an inverse obstacle problem which employs the dynamical scattering data of an acoustic wave over a finite time interval. The unknown obstacle is assumed to be a sound-soft one. The governing equation of the wave is given by the classical wave equation. The wave is generated by the initial data localized outside the obstacle and observed over a finite time interval at a place which is not necessary the same as the support of the initial data. The observed data are the so-called bistatic data. In this paper, an enclosure method which employs the bistatic data and is based on two main analytical formulae is developed. The first one enables us to extract the maximum spheroid with focal points at the centre of the support of the initial data and that of the observation points whose exterior encloses the unknown obstacle of general shape. The second one, under some technical assumption for the obstacle including convexity as an example, indicates the deviation of the geometry of the boundary of the obstacle and the maximum spheroid at the contact points. Several implications of those two formulae are also given. In particular, a constructive proof of the uniqueness of a spherical obstacle using the bistatic data is given.
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Unmanned surface vehicle (USV) path planning is a crucial technology for achieving USV autonomous navigation. Under global path planning, dynamic local obstacle avoidance has become the primary focus for safe USV navigation. In th...
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Unmanned surface vehicle (USV) path planning is a crucial technology for achieving USV autonomous navigation. Under global path planning, dynamic local obstacle avoidance has become the primary focus for safe USV navigation. In this study, a USV autonomous dynamic obstacle avoidance method based on the enhanced velocity obstacle method is proposed in order to achieve path replanning. Through further analysis of obstacles, the obstacle geometric model set in the conventional velocity obstacle method was redefined. A special triangular obstacle geometric model was proposed to reconstruct the velocity obstacle region. The collision time was predicted by fitting the previously gathered data to the detected obstacle’s distance, azimuth, and other relevant data. Then, it is combined with the collision risk to determine when obstacle avoidance should begin and end. In order to ensure safe driving between path points, the international maritime collision avoidance rules (COLREGs) are incorporated to ensure the accuracy of obstacle avoidance. Finally, through numerical simulations of various collision scenarios, it was determined that, under the assumption of ensuring a safe encounter distance, the maximum change rates of USV heading angle are optimized by 17.54%, 58.16%, and 28.63% when crossing, head-on, and overtaking, respectively. The results indicate that, by optimizing the heading angle, the enhanced velocity obstacle method can avoid the risk of ship rollover caused by an excessive heading angle during high-speed movement and achieve more accurate obstacle avoidance action in the event of a safety encounter.
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Advanced driver assistance systems represent considerable progress for improving the safety of vehicles on the road. One group of these systems is based on the detection of obstacles. If positive results are to be achieved these s...
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Advanced driver assistance systems represent considerable progress for improving the safety of vehicles on the road. One group of these systems is based on the detection of obstacles. If positive results are to be achieved these systems must be capable of taking a coherent decision as to which situations involve hazard, in order to avoid false alarms that lead to actions that are not only wrong but disturbing to other road users and cause the driver to lose faith in the system. This paper presents some algorithms to improve those already existing for detecting, identifying and characterising obstacles by means of a laserscanner. The major innovations are: (1) fusing the information from the laserscanner with a positioning system while taking account of the quality of the latter; (2) the criteria for locating obstacles (segmentation process), overcoming the limitations of other approaches that ignore the influence of the obstacle's orientation; (3) the method of defining the characteristic axes of the obstacles, without resorting to tolerance values that are difficult to adjust or reducing the influence of distance measurement errors of the laserscanner. The algorithms were tested with on-track tests using a Sick LRS 1000 long-range laserscanner with satisfactory results being attained that were an improvement on those provided by other methods.
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To guarantee the production of financial information that is useful for economic decision-making, most countries have a set of accounting standard used in preparing the financial statements. Indeed, the use of a common accounting ...
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To guarantee the production of financial information that is useful for economic decision-making, most countries have a set of accounting standard used in preparing the financial statements. Indeed, the use of a common accounting language by all companies operating in the same economic space allows different users to monitor the activities of these entities in time and space and, therefore, take reasonable decisions. Thereby, the international accounting standards are a necessary to clarify the financial disclosure and make reading financial statements conform to a single repository easier. This strengthens the investor's confidence, stimulates the financial market and ensures the best qualities that the financial information should be endowed. In deciding to adopt the international accounting standards IAS/IFRS, Tunisian authorities have launched a challenge to prompt a fast and adequate transition to a new accounting, financial, informational, organizational and internal control systems. However, this presents some obstacles related to the nature of the Tunisian economy which is characterized by a strong presence of small and medium companies, to the differences between the tax system and the accounting system, the conservative attitude of leaders and the high concentration of ownership. The results of our research analysis shows that the conservative attitude of managers and the lack of dynamic and efficient markets are the most important obstacles to adoption of IAS/IFRS in Tunisia according to the Tunisians Certified Public Accountants TCP As). We detailed our analysis for the accounting, tax and economic obstacles. For the accounting, we found that the application of IAS 19, IAS 36 and IFRS 4 are the standards that cause more problems at the moment of their implementation according to the TCPAs. In addition, the deferred tax, the actuarial method and the treatment financial instruments are the most complex treatments in IAS/IFRS. Finally, the differences between the Tunisian accounting system and the international system are undoubtedly an important obstacle. Concerning the tax obstacles, we found that companies prepare their financial statements first in accordance with tax rules. In fact, the differences between the tax rules of the Tunisian accounting system and the IAS/IFRS are undoubtedly an obstacle to a better adoption of them. In addition, another obstacle is the readiness of tax administration for the adoption of the IAS/IFRS. Finally, for the economic obstacles, we found that the IAS/IFRS' adoption and implementation costs and the costs related to their enforcement are the main economic obstacles.
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An obstacle representation of a graph is a mapping of the vertices onto points in the plane and a set of connected regions of the plane (called obstacles) such that the straightline segment connecting the points corresponding to t...
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An obstacle representation of a graph is a mapping of the vertices onto points in the plane and a set of connected regions of the plane (called obstacles) such that the straightline segment connecting the points corresponding to two vertices does not intersect any obstacles if and only if the vertices are adjacent in the graph. Recently, Biedl and Mehrabi (Graph Drawing 2017) studied non-blocking grid obstacle representations of graphs in which the vertices of the graph are mapped onto points in the plane while the straightline segments representing the adjacency between the vertices are replaced by the L1 (Manhattan) shortest paths in the plane that avoid obstacles.In this paper, we introduce the notion of geodesic obstacle representations of graphs with the main goal of providing a generalized model, which comes naturally when viewing line segments as shortest paths in the Euclidean plane. To this end, we extend the definition of obstacle representation by allowing some obstacles-avoiding shortest path between the corresponding points in the underlying metric space whenever the vertices are adjacent in the graph. We consider both general and plane variants of geodesic obstacle representations (in a similar sense to obstacle representations) under any polyhedral distance function in Rd as well as shortest path distances in graphs. Our results generalize and unify the notions of obstacle representations, plane obstacle representations and grid obstacle representations, leading to a number of questions on such representations. (c) 2022 Elsevier B.V. All rights reserved.
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Despite significant progress in robot hardware, the number of mobile robots deployed in public spaces remains low. One of the challenges hindering a wider deployment is that even if a robot can build a map of the environment, for ...
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Despite significant progress in robot hardware, the number of mobile robots deployed in public spaces remains low. One of the challenges hindering a wider deployment is that even if a robot can build a map of the environment, for instance through the use of LiDAR sensors, it also needs to calculate, in real time, a smooth trajectory that avoids both static and mobile obstacles. Considering this scenario, in this paper we investigate whether genetic algorithms can play a role in real-time obstacle avoidance. Historically, the typical use of genetic algorithms was in offline optimization. To investigate whether an online, real-time deployment is possible, we create a family of algorithms called GAVO that combines genetic algorithms with the velocity obstacle model. Through a series of experiments, we show that a carefully chosen chromosome representation and parametrization can achieve real-time performance on the obstacle avoidance problem.
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Home-care manipulation robot requires exploring and performing the navigation task safely to reach the grasping target and ensure human safety in the home environment. An indoor home environment has complex obstacles such as chair...
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Home-care manipulation robot requires exploring and performing the navigation task safely to reach the grasping target and ensure human safety in the home environment. An indoor home environment has complex obstacles such as chairs, tables, and sports equipment, which make it difficult for robots that rely on 2D laser rangefinders to detect. On the other hand, the conventional approaches overcome the problem by using 3D LiDAR, RGB-D camera, or fusing sensor data. The convolutional neural network has shown promising results in dealing with unseen obstacles in navigation by predicting the unseen obstacle from 2D grid maps to perform collision avoidance using 2D laser rangefinders only. Thus, this paper investigated the predicted grid map from the obstacle prediction network result for improving indoor navigation performance using only 2D LiDAR measurement. This work was evaluated by combining the configuration of the various local planners, type of static obstacles, raw map, and predicted map. Our investigation demonstrated that using the predicted grid map enabled all the local planners to achieve a better collision-free path by using the 2D laser rangefinders only rather than the RGB-D camera with 2D laser rangefinders with a raw map. This advanced investigation considers that the predicted map is potentially helpful for future work in the learning-based local navigation system.
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A new method for helping mobile robots to avoid collisions with moving obstacles is proposed. This method adopts the concept of safe sectors in the vector field histogram (VFH) method, but simplifies its description. Moreover, the...
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A new method for helping mobile robots to avoid collisions with moving obstacles is proposed. This method adopts the concept of safe sectors in the vector field histogram (VFH) method, but simplifies its description. Moreover, the new method takes the threat of moving obstacles into account when selecting the direction of motion, and a new speed control law that considers more factors is designed. Hence, it is better at avoiding moving obstacles than the VFH method. Simulation results indicate that the new method also shows many advantages over the dynamic potential field (DPF) method, which is a representative approach for avoiding moving obstacles. Experiments have further verified its applicability.
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