987 resultados para Obstacles


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Mission and path planning for multiple robots in dynamic environments is required when multiple mobile robots or unmanned vehicles are used for geographically distributed tasks. Assigning tasks and paths for robots for cooperatively accomplishing a mission of reaching to number of target points are addressed in this paper. The methodology that is proposed is based on using an adjustable force field which is suitable for dynamic environment. From the force field analysis, the decisions to assign tasks for each robot are then made. The force field is also used to plan a collision free path for each robot. Adjustable weights for the force field model are proposed to satisfy the constraints of the motion. In this research, the constraints are the cooperation of the robots, the precedence between the targets and between robots, and the discrimination between different obstacles. Two simulations for mission and path planning in 2D and 3D dynamic spaces with multiple robots are presented based on the proposed adjustable force filed. The result of the mission and path planning for three robots cooperatively doing eight target points are shown.

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In the last decade RFID technology has become a major contender for managing large scale logistics operations and generating and distributing the massive amount of data involved in such operations. One of the main obstacles to the widespread deployment and adoption of RFID systems is the security issues inherent in them. This is compounded by a noticeable lack of literature on how to identify the vulnerabilities of a RFID system and then effectively identify and develop counter measures to combat the threats posed by those vulnerabilities. In this chapter, the authors develop a conceptual framework for analysing the threats, attacks, and security requirements pertaining to networked RFID systems. The vulnerabilities of, and the threats to, the system are identified using the threat model. The security framework itself consists of two main concepts: (1) the attack model, which identifies and classifies the possible attacks, and (2) the system model, which identifies the security requirements. The framework gives readers a method with which to analyse the threats any given system faces. Those threats can then be used to identify the attacks possible on that system and get a better understanding of those attacks. It also allows the reader to easily identify all the security requirements of that system and identify how those requirements can be met.

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In this paper, we present a real-time obstacle detection system for the mobility improvement for the visually impaired using a handheld Smartphone. Though there are many existing assistants for the visually impaired, there is not a single one that is low cost, ultra-portable, non-intrusive and able to detect the low-height objects on the floor. This paper proposes a system to detect any objects attached to the floor regardless of their height. Unlike some existing systems where only histogram or edge information is used, the proposed system combines both cues and overcomes some limitations of existing systems. The obstacles on the floor in front of the user can be reliably detected in real time using the proposed system implemented on a Smartphone. The proposed system has been tested in different types of floor conditions and a field trial on five blind participants has been conducted. The experimental results demonstrate its reliability in comparison to existing systems.

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Giving robots the ability to autonomously move around in various real-world environments has been a major goal of AI (artificial intelligence) for quite some time. To this end it is vital for robots to be able to perceive their surroundings in 3D; they must be able to estimate the range of obstacles in their path.

Animals navigate through various uncontrolled environments with seemingly little effort. Flying insects, especially, are quite adept at manoeuvring in complex, unpredictable and possibly hostile and hazardous environments.

In this paper it is shown that very simple motion cues, inspired by the visual navigation of flying insects, can be used to provide a mobile robot with the ability to successfully traverse a corridor environment. Equipping an autonomous mobile robot with the ability to successfully navigate real-word environments (in real-time) constitutes a major challenge for AI and robotics. It is in this area that insect based navigation has something to offer.

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Fire is an important natural disturbance process within the Australian landscape, but the complex and hazardous nature of fire creates a conservation management dilemma. For landholders of private conservation lands, management for conservation of biodiversity and risk reduction is complicated. Private conservation landholders in eastern Australia directed far less effort towards fire management than other conservation management actions, despite clearly acknowledging the risk and associated responsibilities of fire management on their lands. Nonetheless, landholders did undertake actions to reduce fuel hazards and prepare for wildfire events on their land. Despite the established role and benefits of fire to many ecosystems in the region, landholder understanding of the ecological role of fire was generally poor. Few landholders were aware of ecologically appropriate fire regimes for the vegetation types on their property, and few undertook fire management actions to achieve ecological outcomes. Site-specific obstacles, lack of fire management knowledge and experience, and legal and containment concerns contributed to the low level of fire management observed. There is a need for property-specific fire management planning across all private conservation lands, to further integrate ecological fire requirements into biodiversity management, and prioritise actions that aim to improve conservation outcomes while safeguarding life and property.

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PURPOSE. To investigate the on-road driving performance of patients with glaucoma.

METHODS. The sample comprised 20 patients with glaucoma and 20 subjects with normal vision, all licensed drivers, matched for age and sex. Driving performance was tested over a 10-km route incorporating 55 standardized maneuvers and skills through residential and business districts of Halifax, Nova Scotia, Canada. Testing was conducted by a professional driving instructor and assessed by an occupational therapist certified in driver rehabilitation, masked to participant group membership and level of vision. Main outcome measures were total number of satisfactory maneuvers and skills, overall rating, and incidence of at-fault critical interventions (application of the dual brake and/or steering override by the driving instructor to prevent a potentially unsafe maneuver). Measures of visual function included visual acuity, contrast sensitivity, and visual fields (Humphrey Field Analyzer; Carl Zeiss Meditec, Inc., Dublin, CA; mean deviation [MD] and binocular Esterman points).

RESULTS. There was no significant difference between patients with glaucoma (mean MD = −1.7 dB [SD 2.2] and −6.5 dB [SD 4.9], better and worse eyes, respectively) and control subjects in total satisfactory maneuvers and skills (P = 0.65), or overall rating (P = 0.60). However, 12 (60%) patients with glaucoma had one or more at-fault critical interventions, compared with 4 (20%) control subjects (odds ratio = 6.00, 95% CI, 1.46–24.69; higher still after adjustment for age, sex, medications and driving exposure), the predominant reason being failure to see and yield to a pedestrian. In the glaucoma group, worse-eye MD was associated with the overall rating of driving (r = 0.66, P = 0.002).

CONCLUSIONS. This sample of patients with glaucoma with slight to moderate visual field impairment performed many real-world driving maneuvers safely. However, they were six times as likely as subjects with normal vision to have a driving instructor intervene for reasons suggesting difficulty with detection of peripheral obstacles and hazards and reaction to unexpected events.

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Indian firms are major global producers of relatively affordable generic medicines. Access to such drugs makes the difference between life and death for billions of people in the Global South. The Economist noted recently that ‘America should not use trade deals to swaddle drugmakers in excessive patent protections’. Nor should the European Union (EU) impose obstacles to the supply of generic drugs by Indian firms beyond those already mandated by the Trade Related Aspects of Intellectual Property Rights (TRIPS) Agreement. Free trade negotiations between the EU (reported to be close to completion) constitute a clear threat to the role of India as the ‘pharmacy of the developing world’.

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Complex capital programs require specialized management techniques, in order to address the volatility, cost overruns, significant delays in completion, and failures with which such programs are typically associated. The need is greater than ever for careful oversight, especially for programs that expend public monies.

Audit is commonly a statutory or governance requirement on such programs, but traditional performance audit techniques and standards may be insufficient for certain types of programs and industries, providing a mere illusion of oversight adequacy instead of the assurance that is needed. In order to most appropriately define the performance audit scope, phrase the solicitation for services, select the audit team, and provide support to the auditors during the engagement, public and private sector entity auditees need to understand the factors that impact performance audit results and effectiveness. The question becomes one of how performance audit can be improved, and stakeholders satisfied regarding program achievements, accountability for resource use, transparency in operations, and risk management.

The author considered program complexity, governance, project controls, the history and evolution of the audit function, stakeholder expectations, assurance, and obstacles to audit, and used this information in conjunction with data from a large sample of 775 audit reports from complex construction programs, to derive questions and conclusions about performance audit results and effectiveness, and comparisons to expenditure audit results. The ultimate goal was to define key components in the execution of performance audits, based on theconclusions of the analysis, in order to improve performance audit findings and thus their applicability and usefulness.

While this study focused on program performance audit, it was also related to the field of program management. Although the data population was concentrated in the area of construction programs, conclusions from this research may also be applied to other complex, multifaceted or phased activities such as projects and programs in other industries (manufacturing, information technology), and also pursuits such as major event planning, company launch, mergers, and large program implementations or rollouts.

The research results clearly demonstrated that different types of findings were generated by different audit scopes. The author observed that typical audit findings focused on routine procedural, accounting, and controls errors. On average, contract expenditure audits questioned only 2.65% of expenditures, and performance audits of large complex programs questioned only 0.03% of expenditures. The majority (72.56%) of the performance audits in the sample yielded no findings or questioned costs.

There were significant positive correlations between: the number of expenditures tested and the number of qualitative findings, inclusion of construction experts on the audit team and the percentage of expenditures questioned, inclusion of construction experts on the audit team and the number of qualitative findings, broader audit scope and the percentage of expenditures questioned, and broader audit scope and the number of qualitative findings. Of these, auditor expertise and audit scope were the driving factors.

There were significant negative correlations between the application of agreed-upon procedures and the percentage of expenditures questioned, and the application of agreed upon-procedures and the number of qualitative findings. It was determined that the significant negative correlation between the application of audit standards and the number of qualitative findings was due to other factors, such as the application of agreed-upon procedures and the lack of construction experts on the audit team.

Other findings, resulting from review of the data, were unrelated to the research questions yet of considerable importance to industry. An extremely high percentage (81%) of the “performance audits” instead applied a very limited set of agreed-upon-procedures (AUP) in the engagement, According to the American Institute of Certified Public Accountants (CPAs), AUP engagements could not be classified as audits. Thus, it was inappropriate for the accounting firms to apply AUP engagements in lieu of a performance audit, and it was especially egregious for them to state in their report that the engagements were conducted in accordance with audit standards, as AUP engagements and the specific audit standards were by their very nature mutually exclusive.

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The G20 forum has acted to crystallise important changes in the architecture of global governance emerging since the 1970s. This has seen the locus of power shift away from the United Nations (UN) System as smaller and poorer states become increasingly adept at exercising their power within UN structures. Yet it is too simple to set the G20 against the UN, for example as minilateralism versus multilateralism. While the UN seems increasingly constrained and less relevant, it is not about to disappear. Moreover, we argue there are two significant obstacles to the G20 claiming the mantle of dominant global governance institution. First, that minilateralism is still a form of multilateralism, and ultimately subject to the same problems with the generation of consensus if extended, as in the G20, to include sufficiently diverse state members for a claim of legitimacy. Second, its emergence from the Global Financial Crisis and historical focus on financial governance means its agenda is excessively narrow at a time when food and environmental crises command similar global political significance. We conclude by considering some of the different elements of the emerging G20/UN dynamic, and whether this emerging dialectic can enhance prospects for wide ranging reforms to global trade, finance and economic structures that are currently incapable of functioning sustainably or preventing wide scale famine.

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Although this book has a specific focus on Australian firms doing business in China, the important and unique contribution this book makes will help you and anyone in an organization that is considering doing business in China. China maintains a high growth economy and is currently the second largest in the world. This book, which includes results from research interviews conducted with business executives from 40 organizations, will assist in preparing to do business in China. This book takes you through the various elements associated with doing business in China, including the opportunities that are available and the obstacles that organizations can face, supported by data from real businesses internationalizing to China. It examines key areas including the foreign direct investment and trade framework, Chinese culture, political and legal frameworks, intellectual property regulations, motivations for internationalization, market entry strategy, and human resource management issues.

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Citizen participation, enabled by electronic means, grows, in parallel with government's apparent failure to promote it. Organisations such as Getup and Moveon flourish; the BBC announced in 2003 that 'Internet-based political activism is happening...The BBC wants to help a wider audience find their voice by tackling obstacles to greater participation' (http://www.opendemocracy.net). (Kevill, 2003). Such actions echo, perhaps, the enthusiastic adoption of the Internet by activist media groups, particularly Indymedia. This paper presents a response to this situation. It provides a richer account of the contradictory rise of e-government without e-governance, and examines the potential for media-based participatory engagement to complement e-government. It presents two models of the future of electronically mediated citizen engagement: the first involving agonistic relations between government and citizenry, with civic participation occurring outside of government-approved forums; the second involving the intimate linking of governmental transactions to participation by those citizens engaged in them. Finally it will outline mechanisms for researching the capacity of either or both models to sustain effective participation.

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This paper seeks to animate discussion around how social class operates with adolescent girls from low socio-economic status backgrounds to shape and inform their decisions about participation in physical activity (PA) inside and outside of school. Examining the instance of girls in a single secondary school in an Australian regional town, the paper questions the impact of class and how the girls experience the obstacles, impediments and interferences to participation in PA. These girls are portrayed as living multiple, complex and embodied subjectivities that shape and are informed by the relational geographies in which they are located, as they interact ‘with’, ‘to’ and ‘between’ the social, emotional and classed hierarchies that require them to access familial and other resources in making decisions about participation in PA.

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Background : The development of e-mental health interventions to treat or prevent mental illness and to enhance wellbeing has risen rapidly over the past decade. This development assists the public in sidestepping some of the obstacles that are often encountered when trying to access traditional face-to-face mental health care services. Objective : The objective of our study was to investigate the posttreatment effectiveness of five fully automated self-help cognitive behavior e-therapy programs for generalized anxiety disorder (GAD), panic disorder with or without agoraphobia (PD/A), obsessive–compulsive disorder (OCD), posttraumatic stress disorder (PTSD), and social anxiety disorder (SAD) offered to the international public via Anxiety Online, an open-access full-service virtual psychology clinic for anxiety disorders. Methods : We used a naturalistic participant choice, quasi-experimental design to evaluate each of the five Anxiety Online fully automated self-help e-therapy programs. Participants were required to have at least subclinical levels of one of the anxiety disorders to be offered the associated disorder-specific fully automated self-help e-therapy program. These programs are offered free of charge via Anxiety Online. Results : A total of 225 people self-selected one of the five e-therapy programs (GAD, n = 88; SAD, n = 50; PD/A, n = 40; PTSD, n = 30; OCD, n = 17) and completed their 12-week posttreatment assessment. Significant improvements were found on 21/25 measures across the five fully automated self-help programs. At postassessment we observed significant reductions on all five anxiety disorder clinical disorder severity ratings (Cohen d range 0.72–1.22), increased confidence in managing one’s own mental health care (Cohen d range 0.70–1.17), and decreases in the total number of clinical diagnoses (except for the PD/A program, where a positive trend was found) (Cohen d range 0.45–1.08). In addition, we found significant improvements in quality of life for the GAD, OCD, PTSD, and SAD e-therapy programs (Cohen d range 0.11–0.96) and significant reductions relating to general psychological distress levels for the GAD, PD/A, and PTSD e-therapy programs (Cohen d range 0.23–1.16). Overall, treatment satisfaction was good across all five e-therapy programs, and posttreatment assessment completers reported using their e-therapy program an average of 395.60 (SD 272.2) minutes over the 12-week treatment period. Conclusions : Overall, all five fully automated self-help e-therapy programs appear to be delivering promising high-quality outcomes; however, the results require replication.

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A complex regulatory package is likely to be necessary to effectively reduce obesity prevalence in developed countries. This study investigated the barriers and facilitators to implementing regulatory interventions to prevent obesity within the executive arm of the Australian Commonwealth Government. Policy reviews were conducted on nine government departments to understand their roles and interests in obesity. From this process we identified regulatory review carried out by the Office of Best Practice Regulation as possibly posing a barrier to law reform for obesity prevention, along with the complexity of the food policymaking structures. The policy reviews informed subsequent in-depth semi-structured interviews with senior Commonwealth government officers (n = 13) focused on refining our understanding of the barriers to enacting obesity prevention policy. In addition to the two barriers already identified, interviewees identified a lack of evidence for interventions, which would reduce obesity prevalence, and the influence of politicians on executive decisions as posing obstacles. Most interviewees believed that the barriers to regulating to prevent obesity were strong and that intervention by elected politicians would be the most likely method of implementing obesity prevention policy.

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1. Habitat heterogeneity and predator behaviour can strongly affect predator–prey interactions but these factors are rarely considered simultaneously, especially when systems encompass multiple predators and prey.

2. In the Arctic, greater snow geese Anser caerulescens atlanticus L. nest in two structurally different habitats: wetlands that form intricate networks of water channels, and mesic tundra where such obstacles are absent. In this heterogeneous environment, goose eggs are exposed to two types of predators: the arctic fox Vulpes lagopus L. and a diversity of avian predators. We hypothesized that, contrary to birds, the hunting ability of foxes would be impaired by the structurally complex wetland habitat, resulting in a lower predation risk for goose eggs.

3. In addition, lemmings, the main prey of foxes, show strong population cycles. We thus further examined how their fluctuations influenced the interaction between habitat heterogeneity and fox predation on goose eggs.

4. An experimental approach with artificial nests suggested that foxes were faster than avian predators to find unattended goose nests in mesic tundra whereas the reverse was true in wetlands. Foxes spent 3·5 times more time between consecutive attacks on real goose nests in wetlands than in mesic tundra. Their attacks on goose nests were also half as successful in wetlands than in mesic tundra whereas no difference was found for avian predators.

5. Nesting success in wetlands (65%) was higher than in mesic tundra (56%) but the difference between habitats increased during lemming crashes (15%) compared to other phases of the cycle (5%). Nests located at the edge of wetland patches were also less successful than central ones, suggesting a gradient in accessibility of goose nests in wetlands for foxes.

6. Our study shows that the structural complexity of wetlands decreases predation risk from foxes but not avian predators in arctic-nesting birds. Our results also demonstrate that cyclic lemming populations indirectly alter the spatial distribution of productive nests due to a complex interaction between habitat structure, prey-switching and foraging success of foxes.