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RobotTeamSim – 3D visualization of cooperative mobile robot missions in gazebo virtual environment

Augusto, Gonçalo Nuno dos Santos
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Dissertação de Mestrado
Português
Relevância na Pesquisa
65.86%
This dissertation intends to create a simulation of search and rescue (SaR) missions using Gazebo virtual world and Robot Operating System (ROS). The simulator is evaluated with multiple robots search using the Robotic Darwinian Particle Swarm Optimization (RDPSO) exploration algorithm, considering several real-world phenomena, such as radio frequency (RF) and voice. Although the RDPSO algorithm has already been developed and evaluated in Matlab environment, it cannot be directly implemented in real platforms. To address this disadvantage, ROS was chosen to implement the algorithm and, due to its compatibility with ROS, Gazebo was chosen as the simulation platform to evaluate multi-robot systems in SaR scenarios. For the RDPSO to be fully implemented, the RF signal and voice propagation models were equally implemented in ROS. For that matter, mathematic models, previously proposed in the literature, are analyzed and a study about the environment noise influence in missions of SaR based on voice localization is conducted. The RF model was simulated using the multi-wall method, which does not only consider the free space signal loss but also the loss of walls with different properties (e.g., thickness and type). The voice model is based on the RF model by adjusting the parameters to better adapt to the voice properties. The RDPSO algorithm...

MRsensing: environmental monitoring and context recognition with cooperative mobile robots in catastrophic incidents

Ferreira, Nuno Filipe Loureiro
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Dissertação de Mestrado
Português
Relevância na Pesquisa
75.7%
Multi-sensor information fusion theory concerns the environmental perception activities to combine data from multiple sensory resources. Humans, as any other animals, gather information from the environment around them using different biological sensors. Combining them allows structuring the decisions and actions when interacting with the environment. Under disaster conditions, effective mult-robot information sensor fusion can yield a better situation awareness to support the collective decision-making. Mobile robots can gather information from the environment by combining data from different sensors as a way to organize decisions and augment human perception. The is especially useful to retrieve contextual environmental information in catastrophic incidents where human perception may be limited (e.g., lack of visibility). To that end, this work proposes a specific configuration of sensors assembled in a mobile robot, which can be used as a proof of concept to measure important environmental variables in an urban search and rescue (USAR) mission, such as toxic gas density, temperature gradient and smoke particles density. This data is processed through a support vector machine classifier with the purpose of detecting relevant contexts in the course of the mission. The outcome provided by the experiments conducted with TraxBot and Pioneer-3DX robots under the Robot Operating System framework opens the door for new multi-robot applications on USAR scenarios. This work was developed within the CHOPIN research project1 which aims at exploiting the cooperation between human and robotic teams in catastrophic accidents.; O tema da fusão sensorial abrange a perceção ambiental para combinar dados de vários recursos naturais. Os seres humanos...

Proposta de modelo de veículos aéreos não tripulados (VANTs) cooperativos aplicados a operações de busca.; Proposal of cooperative unmanned aerial vehicles (UAVs) model applied to search operations.

Chaves, Áquila Neves
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 18/12/2012 Português
Relevância na Pesquisa
75.82%
Os Veículos Aéreos Não Tripulados (VANTs) são ideais para operações de risco e estressante para o ser humano são as chamadas dull, dirty and dangerous missions. Portanto, uma importante aplicação desse tipo de robô aéreo diz respeito a operações de busca envolvendo múltiplos VANTs cooperativos, em que há risco de colisões entre aeronaves e o tempo de um voo é limitado, entre outros fatores, pela capacidade de um piloto trabalhar sem descanso. Entretanto, apesar de atualmente verificar-se um crescente número de pesquisas envolvendo VANTs e do grande potencial existente na utilização de VANTs, operações de busca cooperativas ainda não estão ocorrendo. Esse assunto é uma área de estudo multidisciplinar e nascente, que possui diversas linhas de pesquisa. Diferentes algoritmos de navegação e padrões de busca foram estudados visando selecionar o(s) mais adequado(s). Além disso, apresenta-se, neste trabalho, uma visão geral sobre os mecanismos de coordenação multiagente e avalia a adequação de cada uma delas à coordenação distribuída de agentes (VANTs), visando cooperação. Assim, com o objetivo de melhorar o desempenho de uma operação de busca, esta pesquisa de mestrado propõe um modelo de VANTs cooperativos que combina mecanismos de coordenação multiagente...

Emergency Communication

Shaw, Rajib; Peary, Brett; Ideta, Ai; Takeuchi, Yukiko
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Português
Relevância na Pesquisa
65.83%
The Great East Japan Earthquake (GEJE) caused immense damage and congestion in telephone infrastructure, including 1.9 million fixed-line services and 29,000 mobile phone base stations. Government radio communication infrastructure was also seriously damaged. Voice messages were widely used to confirm whether family members and relatives were safe, and satellite phones played a crucial role in emergency communication during the response stage. Social media was extensively used for search and rescue, as well as for fundraising. Social media and community radio reach two distinct age groups: social media for the younger generation and community radio for the older generation. Communication infrastructure is indispensable in securing government functions and protecting lives and property during disasters. Communication systems are used to disseminate warnings to the public, to enable search and rescue organizations to communicate among themselves, and to confirm the safety of family members and relatives. Community radios can provide local information such as times and locations where emergency water and food supplies or relief goods will be delivered.

Finding the "sweet spot" for catastrophic incident search and rescue

Bleakney, Eric M.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
65.86%
CHDS State/Local; This thesis examines the national preparedness to conduct catastrophic incident search and rescue (SAR) using organization-specific doctrine, concept plans, congressional research reports and testimonies, after action reviews, periodicals, federal government plans, interviews, a focus group and two benchmark studies. The research indicates that individual organizations conduct SAR activities well, but combined, joint and interagency catastrophic search and rescue preparations are lacking. Should another catastrophic incident occur tomorrow, the SAR results will likely exhibit the same unacceptable inefficiency as was found in Hurricane Katrina. Finding the sweet spot for response to catastrophic incidents is needed. There are three major findings: First, a national strategy for SAR is needed. This epic effort will help to improve the interagency coordination between equity holders of the search and rescue megacommunity and set the conditions to improve catastrophic incident SAR. Secondly, a Joint Air Ground Coordination Center (JAGCC) is critical to effective response operations. Two benchmark studies suggest a framework for developing a SAR coordination center using experiences of the wildland firefighting community and the United States Secret Service. Finally...

Cost and operational effectiveness analysis of alternative force structures for fulfillment of the United States Marine Corps operational support airlift and search and rescue missions

Chase, Eric T.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
65.86%
This thesis provides a preliminary cost and operational effectiveness analysis of alternative force structures for the United States Marine Corps operational support airlift and search and rescue missions. The four alternative force structures include C-12s and CH-46Es, C-35s and CH-46Es and HV-609s. Lifecycle cost analysis of the alternative force structures using Crystal Bali forecasting provides a 90% upper confidence level lifecycle cost estimate that identifies a mix of C-35s for operational support airlift and CH-46Es for search and rescue as the least expensive alternative. Operational effectiveness analysis provides a measure of overall utility for each of the four alternative force structures based on five measures of effectiveness. The measures of effectiveness examined are air travel time, total travel time, landing site requirements, range versus time on station, and payload versus range. Analytical hierarchy process rankings indicate that the HV-609 is the preferred alternative considering these measures of effectiveness. Analysis of cost versus operational effectiveness identifies the HV-609 as the most cost and operationally effective alternative for fulfilling the Marine Corps operational support airlift and search and rescue missions.

FEMA Urban Search and Rescue Teams : Considering an Improved Strategy for an Evolving Homeland Security Enterprise

Poirier, Alfred
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
65.86%
CHDS State/Local; The United States governments role in preparing for, preventing, responding to, and recovering from all domestic disasters is coordinated by the Federal Emergency Management Agency (FEMA). Further, FEMA is designated as the primary agency responsible for coordinating Structural Collapse (Urban) Search and Rescue (US and R) situations in the National Response Framework. Since the inception of FEMA resources intended for response to US and R missions, the national search and rescue system has evolved, along with the numbers and types of other resources available to assist in US and R missions. Nonetheless, a disconnect remains, with no common national US and R strategy that effectively brings together available federal resources from FEMA, the Department of Defense, and other partner agencies. FEMA states that urban search and rescue is considered a multi-hazard discipline, as the teams can hypothetically be utilized for response to a wide variety of natural and man-made emergencies or disasters. Although the present FEMA US and R task force model has worked well for certain types of disasters, this thesis explores responses to past events and considers a new strategy that could allow the US and R teams to be used more effectively and efficiently in an evolving Homeland Security enterprise.

A capability-based approach to analyzing the effectiveness and robustness of an offshore patrol vessel in the search and rescue mission

Ashpari, Mohammad
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
65.96%
In this thesis, a model of effectiveness for an offshore patrol vessel conducting search and rescue missions is developed and described. Beginning with a brief overview of work done by colleagues from the University of Genoa, Italy, as well as documents currently in use by the United States Navy and Coast Guard for search and rescue, this thesis provides a link between physical ship design factors and the operational effectiveness of a search and rescue mission. The methodology involved developing a search model, then using an enhanced experimental design to explore how operational noise factors, along with physical ship characteristics, impact the effectiveness of search and rescue. Those characteristics include the ships maximum speed, the number of helicopters onboard, and the number of unmanned aerial vehicles onboard. Operational noise factors include the visibility, the direction of the wind, the maximum speeds as well as the search speeds of the other search entities, the distance to the last known datum, the uncertainty radius of the last known datum, and other environmental factors. Four metamodels are then developed to express which factors have the greatest impact on the performance of the ship as a function of cumulative probability detection threshold in a search and rescue mission.

An instructional design reference mission for search and rescue operations

Giammarco, Kristin; Hunt, Spencer; Whitcomb, Clifford
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Relatório
Português
Relevância na Pesquisa
95.8%
Approved for public release; distribution in unlimited.; The objective of this instructional guide is to help learners gain practice with the proper framing of a problem for analysis, the first and most critical step in systems architecture and design. A Design Reference Mission (DRM) is outlined and populated with example content for a notional Search and Rescue (SAR) mission. The DRM establishes an operational context, description(s) of the environment and situations in which a system of interest is expected to operate, an operational narrative containing enough detail to generate multiple operational scenario variants, a sequence of operational activities and interactions between each system and other systems in its environment, and measures for establishing goals for mission success. The DRM is to be used to derive specific scenarios for use in making design decisions concerning candidate operational and solution architectures aimed at satisfying the mission success requirements.; The Consortium for Robotics and Unmanned Systems Education and Research (CRUSER)

Evaluating Florida's urban search and rescue system : its current structure and future direction; Evaluating the Florida urban search and rescue system: its future structure and direction.

DeIorio, John J.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: xii, 65 p. ;
Português
Relevância na Pesquisa
95.95%
CHDS State/Local; Since September 12, 2001, The Florida Urban Search and Rescue System (FLUSAR) in Florida has grown from a nascent system to a full-fledged, multi-tiered, statewide search and rescue system. Through an urgent need for Urban Search and Rescue (US and R) capabilities, good planning and a unity of purpose after September 11, 2001, Florida was able to establish a system that is emulated by other states. However, due to a lack of state control, sustainable funding, a strategic plan and policies to protect integral members from professional liability, the system is in jeopardy of ceasing to exist. If this were to occur, Florida could not adequately protect its citizens during emergencies that cause structural collapse. By examining the qualitative information gleaned from the literature review, a survey of state US and R systems, interviews with personnel who were involved with the establishment of FLUSAR, or have a role in other state's US and R systems, and the author's experience with the FLUSAR system with state and local governments, this thesis will also evaluate the present capability of the US and R system within the state of Florida and provide a description of where FLUSAR has been, where it is today and to recommend changes for the future. In order to ensure the highest degree of performance and accountability to the citizens of Florida...

Persistent vision-based search and track using multiple UAVs

Bethke, Brett (Brett M.)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 98 leaves
Português
Relevância na Pesquisa
75.62%
Unmanned aerial vehicles (UAVs) have attracted interest for their ability to carry out missions such as border patrol, urban traffic monitoring, persistent surveillance, and search and rescue operations. Most of these missions require the ability to detect and track objects of interest on or near the ground. In addition, most of the missions are inherently long-duration, requiring multiple UAVs to cooperate over time periods longer than the endurance of a single vehicle. This thesis presents a framework to enable such missions to be carried out autonomously and robustly. First, a technique for vision-based target detection and bearing determination that utilizes a video camera onboard each UAV is presented. The technique is designed to detect the presence of targets of interest in the camera video stream and determine the bearing from the UAV to the target even when the video data is noisy. Next, a cooperative, bearings-only target estimation algorithm is presented. The algorithm is shown to provide better estimates of a target's position and velocity in three dimensions than could be achieved by a single vehicle, while being computationally efficient and naturally distributable among multiple UAVs.; (cont. )Next, a task assignment algorithm that incorporates closed-loop feedback on the performance of individual UAVs and sensor suites is developed...

Unifying model-based programming and randomized path planning through optimal search

Walcott, Aisha, 1978-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 122 p.; 7312414 bytes; 7327793 bytes; application/pdf; application/pdf
Português
Relevância na Pesquisa
65.84%
The deployment of robots at the World Trade Center (WTC) site after September 11, 2001, highlighted the potential for robots to aid in search and rescue missions that pose great threats and challenges to humans. However, robots that are tele-operated and tethered for power and communication are restricted in terms of their operational area. Thus, rescue robots must be equipped with onboard autonomy that enables them to select feasible plans on their own, within their physical and computational limitations. There are three main characteristics that a rescue robot's onboard system must posses. First, the system must be able to generate plans for mobile systems, that is, plans with activities and paths. Second, in order to operate as efficiently as possible, particularly in emergency situations, the system must be globally optimal. Third, the system must be able to generate plans quickly. This thesis introduces a novel autonomous control system that interleaves methods for spatial and activity planning, by merging model-based programming with roadmap-based path planning. The primary contributions are threefold. The first contribution is a model that represents possible mission strategies with activities that have cost and are constrained to a location. The second is an optimal pre-planner that reasons through the possible mission strategies in order to quickly find the optimal feasible strategy. The third contribution is a unified...

The Race to Save Lives: Demonstrating the Use of Social Media for Search and Rescue Operations

Simon, Tomer; Adini, Bruria; El-Hadid, Mohammed; Goldberg, Avishay; Aharonson-Daniel, Limor
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 06/11/2014 Português
Relevância na Pesquisa
65.91%
Importance: Utilizing social media in an emergency can enhance abilities to locate and evacuate casualties more rapidly and effectively, and can contribute towards saving lives following a disaster, through better coordination and collaboration between search and rescue teams. Objective: An exercise was conducted in order to test a standard operating procedure (SOP) designed to leverage social media use in response to an earthquake, and study whether social media can improve joint Israeli-Jordanian search and rescue operations following a regional earthquake. Design: First responders from both Jordan and Israel were divided into two mixed groups of eight people each, representing joint (Israeli-Jordanian) EMS teams. Simulated patients were dispersed throughout the Ben-Gurion University Campus. The first search and rescue team used conventional methods, while the second team also used social media channels (Facebook and Twitter) to leverage search and rescue operations. Participants: Eighteen EMS and medical professionals from Israel and Jordan, which are members of the Emergency Response Development and Strategy Forum working group, participated in the exercise. Results: The social media team found significantly more mock casualties...

Advances in Search and Rescue at Sea

Breivik, Øyvind; Allen, Arthur Addoms; Maisondieu, Christophe; Olagnon, Michel
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/11/2012 Português
Relevância na Pesquisa
75.91%
A topical collection on "Advances in Search and Rescue at Sea" has appeared in recent issues of Ocean Dynamics following the latest in a series of workshops on "Technologies for Search and Rescue and other Emergency Marine Operations" (2004, 2006, 2008 and 2011), hosted by IFREMER in Brest, France. Here we give a brief overview of the history of search and rescue at sea before we summarize the main results of the papers that have appeared in the topical collection. Keywords: Search and rescue (SAR), Trajectory modelling, Stochastic Lagrangian ocean models, Lagrangian measurement methods, ocean surface currents.; Comment: 11 pages; Ocean Dynamics (2012)

An Operational Search and Rescue Model for the Norwegian Sea and the North Sea

Breivik, Øyvind; Allen, Arthur A
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 04/11/2011 Português
Relevância na Pesquisa
75.89%
A new operational, ensemble-based search and rescue model for the Norwegian Sea and the North Sea is presented. The stochastic trajectory model computes the net motion of a range of search and rescue objects. A new, robust formulation for the relation between the wind and the motion of the drifting object (termed the leeway of the object) is employed. Empirically derived coefficients for 63 categories of search objects compiled by the US Coast Guard are ingested to estimate the leeway of the drifting objects. A Monte Carlo technique is employed to generate an ensemble that accounts for the uncertainties in forcing fields (wind and current), leeway drift properties, and the initial position of the search object. The ensemble yields an estimate of the time-evolving probability density function of the location of the search object, and its envelope defines the search area. Forcing fields from the operational oceanic and atmospheric forecast system of The Norwegian Meteorological Institute are used as input to the trajectory model. This allows for the first time high-resolution wind and current fields to be used to forecast search areas up to 60 hours into the future. A limited set of field exercises show good agreement between model trajectories...

Automated Synthesis of Controllers for Search and Rescue from Temporal Logic Specifications

Wiltsche, Clemens
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 25/04/2013 Português
Relevância na Pesquisa
75.83%
In this thesis, the synthesis of correct-by-construction controllers for robots assisting in Search and Rescue (SAR) is considered. In recent years, the development of robots assisting in disaster mitigation in urban environments has been actively encouraged, since robots can be deployed in dangerous and hazardous areas where human SAR operations would not be possible. In order to meet the reliability requirements in SAR, the specifications of the robots are stated in Linear Temporal Logic and synthesized into finite state machines that can be executed as controllers. The resulting controllers are purely discrete and maintain an ongoing interaction with their environment by changing their internal state according to the inputs they receive from sensors or other robots. Since SAR robots have to cooperate in order to complete the required tasks, the synthesis of controllers that together achieve a common goal is considered. This distributed synthesis problem is provably undecidable, hence it cannot be solved in full generality, but a set of design principles is introduced in order to develop specialized synthesizable specifications. In particular, communication and cooperation are resolved by introducing a verified standardized communication protocol and preempting negotiations between robots. The robots move on a graph on which we consider the search for stationary and moving targets. Searching for moving targets is cast into a game of cops and robbers...

Strategic Control of Proximity Relationships in Heterogeneous Search and Rescue Teams

Flushing, Eduardo Feo; Gambardella, Luca M.; Di Caro, Gianni A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 16/12/2013 Português
Relevância na Pesquisa
65.87%
In the context of search and rescue, we consider the problem of mission planning for heterogeneous teams that can include human, robotic, and animal agents. The problem is tackled using a mixed integer mathematical programming formulation that jointly determines the path and the activity scheduling of each agent in the team. Based on the mathematical formulation, we propose the use of soft constraints and penalties that allow the flexible strategic control of spatio-temporal relations among the search trajectories of the agents. In this way, we can enable the mission planner to obtain solutions that maximize the area coverage and, at the same time, control the spatial proximity among the agents (e.g., to minimize mutual task interference, or to promote local cooperation and data sharing). Through simulation experiments, we show the application of the strategic framework considering a number of scenarios of interest for real-world search and rescue missions.; Comment: In Proceedings of the 3rd IROS Workshop on Robots and Sensors integration in future rescue INformation system (ROSIN), Tokyo, Japan, November 7, 2013

A Brief Summary of Search and Rescue Literature: A Report to COT Netherlands

Trainor, Joseph; Aguirre, Benigno E.; McNeil, Sue
Fonte: Disaster Research Center Publicador: Disaster Research Center
Tipo: Relatório
Português
Relevância na Pesquisa
75.86%
The accumulated of research on search and rescue (SAR) allows us to identify repeating patterns that should be considered in the development of an effective plan for national emergency response: (1) SAR is not simply an organizational activity, it necessarily includes the social and collective behavior of volunteers; (2) Preexisting and emergent organizations, social statuses and social identities, such as neighborhood and work place relationships and family and neighborhood social identities, serve as a basis for the emergence of new SAR groups and constitute the fundamental concepts and categories that are needed to understand and improve SAR activities; (3) SAR activities do not emerge from a vacuum; as an example of the principle of continuity advocated by Quarantelli and Dynes (1977), there are always elements of the traditional social structure embedded within collective behavior entities, and their emergent division of labor, role structure, and activities are also dependent on prior social relationships and forms of social organization in the community or region; (4) Breakdown models of social organizational patterns in disaster are not useful to understand SAR. Television reports and misinformed reporters often misinterpret throngs of people moving seemingly at random at the sites destroyed by various hazards...

Local Search and Rescue Teams in the United States

Denver, Megan; Perez, Jaime; Aguirre, Benigno E.
Fonte: Disaster Research Center Publicador: Disaster Research Center
Tipo: Outros Formato: 12697659 bytes; application/pdf
Português
Relevância na Pesquisa
95.86%
Arguably one of the least appreciated actors in disaster response is local search and rescue (SAR) teams, despite their importance in saving lives. In contrast to fire and police departments, federal Urban Search and Rescue (US&R) taskforces, the Red Cross, the Salvation Army, and other well known disaster response organizations, local SAR teams have not received much recognition or support at the national level. This is the case even in the contemporary context in which "homeland security" and "improvements of resiliency" in American institutions are buzzwords. Their "invisibility" is also reflected in the dearth of research literature about them in the field of emergency management and the social sciences of disasters. An exception to this is the work by Lois (1999), who looked at the dynamics of a local SAR team and provided an in-depth view of the authority structure and the slow advancement of new members in the hierarchy of the group. Earlier, Drabek (1981) also provided insights by surveying local SAR teams in Washington and Wyoming to better understand attitudes towards regulations, agency jurisdictions, SAR funding, and issues of legal liability. While these efforts begin to explore important questions in this understudied field...

Busca e resgate no mar; Ocean search and rescue

Teixeira, Marcelo
Fonte: Universidade de São Paulo. Faculdade de Medicina Publicador: Universidade de São Paulo. Faculdade de Medicina
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; Formato: application/pdf
Publicado em 18/03/2012 Português
Relevância na Pesquisa
65.81%
Os atendimentos a vítimas que estão no mar principalmente em regiões distantes da costa exigem uma equipe extremamente especializada e equipada, podendo envolver aeronaves e embarcações. Algumas têm duração de dias. A adaptação do ser humano para o ambiente aquático é frágil, reduzindo o tempo de sobrevivência, principalmente nos acidentes em que as vítimas não contam com apoio de balsas ou kits de sobrevivência.