953 resultados para Unbounded operators
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This is an exploratory research, with a quantitative approach, developed with the objective of analyzing the work and of life situations that can offer risks to the workers' health involved in the manual and automated cut of the sugar cane. The sample was composed by 39 sugar cane cutters and 16 operators of harvesters. The data collection occurred during the months of July and August of 2006, by the technique of direct observation of work situations and workers' homes and through interviews semi-structured. The interviews were recorded and later transcribed. Data were analyzed according to Social Ecological Theory. It was observed that the workers deal with multiple health risk situations, predominantly to the risks of occurrence of respiratory, musculoskeletal and psychological problems and work-related accidents due to the work activities. The interaction of individual, social and environmental factors can determine the workers' tendency to falling ill.
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In the past, sensors networks in cities have been limited to fixed sensors, embedded in particular locations, under centralised control. Today, new applications can leverage wireless devices and use them as sensors to create aggregated information. In this paper, we show that the emerging patterns unveiled through the analysis of large sets of aggregated digital footprints can provide novel insights into how people experience the city and into some of the drivers behind these emerging patterns. We particularly explore the capacity to quantify the evolution of the attractiveness of urban space with a case study of in the area of the New York City Waterfalls, a public art project of four man-made waterfalls rising from the New York Harbor. Methods to study the impact of an event of this nature are traditionally based on the collection of static information such as surveys and ticket-based people counts, which allow to generate estimates about visitors’ presence in specific areas over time. In contrast, our contribution makes use of the dynamic data that visitors generate, such as the density and distribution of aggregate phone calls and photos taken in different areas of interest and over time. Our analysis provides novel ways to quantify the impact of a public event on the distribution of visitors and on the evolution of the attractiveness of the points of interest in proximity. This information has potential uses for local authorities, researchers, as well as service providers such as mobile network operators.
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This final project was made for the Broadband/Implementation department of TeliaSonera Finland. The question to be examined is if the operator should replace multiple ADSL connections implemented over a leased line with Multi-Dwelling access based on an Ethernet/Optical Fibre access network. The project starts with describing the technology related to these access network solu-tions and presents the technology that is used in TeliaSonera Finland's access network. It continues from the technology to describe the problem with some of the ADSL implemen-tations of TeliaSonera. The problem is the implementations done over a leased line that can cost TeliaSonera over years as much as a possible investment to extend network when there is several lines leased to the same building. The project proposes a Multi-Dwelling access as a solution to this problem and defines the circumstances when to use it. After a satisfactory solution has found the project takes a view how implementation of the solution might alter the network and a new problem is found. When used commonly to replace need of ADSL implementation Multi-Dwelling access would significantly increase optical cable congestion near operators POP. As a final deed this project also proposes a technical change to existing way to implement multi-dwelling access with EPON technology.
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Coherent regulation of landscape as a resource is a major challenge. How can the development interests of some actors (eg cable car operators and property developers) be reconciled with those of others (agriculture, forestry) and with conservation of biodiversity and scenic value? To help understand how the newly introduced Regional Nature Parks (RNPs) can improve the coherence of the regulation regime in Switzerland, we highlight current direct mechanisms for regulation of landscape as a resource (bans, inventories, subsidies) as well as indirect mechanisms (taking place through the regulation of the physical basis of landscapes, eg forest, land, and water planning policies). We show that RNPs are fundamentally innovative because they make it possible to manage and coordinate indirect strategies for appropriate regulation of resources at a landscape scale. In other words, RNPs enable organization of governance of landscape as a resource in a perimeter that is not necessarily restricted to administrative boundaries.
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Each winter, the Iowa Department of Transportation (Iowa DOT) maintenance operators are primarily responsible for plowing snow off federal and state roads. Drivers typically work long shifts under treacherous conditions. In addition to properly navigating the vehicle, drivers are required to operate several plowing mechanisms simultaneously, such as plow controls and salt sprayers. However, operators have few opportunities during the year to practice and refine their skills. An ideal training program would provide operators with the opportunity to practice these skills under realistic yet safe conditions, as well as provide basic training to novice or less-experienced operators. Recent technological advancements have made driving simulators a desirable training and research tool. This literature review discusses much of the recent research establishing simulator fidelity and espousing its applicability. Additionally, this report provides a summary of behavioral and eye tracking research involving driving simulators. Other research topics include comparisons between novice and expert drivers’ behavioral patterns, methods for avoiding cybersickness in virtual environments, and a synopsis of current personality measures with respect to job performance and driving performance. This literature review coincides with a study designed to examine the effectiveness of virtual reality snowplow simulator training for current maintenance operators, using the TranSim VS III truck and snowplow simulator recently purchased by the Iowa DOT.
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Objective To identify the difficulties of families with children and/or adolescents with mental disorder. Method This is an integrative review. In December 2013, an electronic search was performed on Latin American Caribbean Literature on Health Sciences databases (LILACS) and on Electronic Medicus Index of the National Library of Medicine (MEDLINE) indexed in the Health Virtual Library (BVS) using a combination of descriptors and boolean operators as follows: mental disorders and child or adolescent and caregivers and/not health staff. Results 557 studies were identified, of which 15 were selected for this study. The findings indicated difficulties related to the care for or to interaction with children/adolescents with mental disorder. Conclusion The studies revealed difficulties related to everyday practices of care and feelings expressed during care practices, as well as in relationships with children or adolescents with mental disorder.
Resumo:
Each winter, Iowa Department of Transportation (Iowa DOT) maintenance operators are responsible for plowing snow off federal and state roads in Iowa. Drivers typically work long shifts under treacherous conditions. In addition to properly navigating the vehicle, drivers are required to operate several plowing mechanisms simultaneously, such as plow controls and salt spreaders. There is little opportunity for practicing these skills in real-world situations. A virtual reality training program would provide operators with the opportunity to practice these skills under realistic yet safe conditions, as well as provide basic training to novice or less-experienced operators. In order to provide such training to snowplow operators in Iowa, the Iowa DOT purchased a snowplow simulator. The Iowa DOT commissioned a study through Iowa State University designed to (1) assess the use of this simulator as a training tool and (2) examine personality and other characteristics associated with being an experienced snowplow operator. The results of this study suggest that Iowa DOT operators of all ages and levels of experience enjoyed and seemed to benefit from virtual reality snowplow simulator training. Simulator sickness ratings were relatively low, implying that the simulator is appropriate for training a wide range of Iowa DOT operators. Many reported that simulator training was the most useful aspect of training for them.
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We explain why European trucking carriers are much smaller and rely more heavily on owner-operators(as opposed to employee drivers) than their US counterparts. Our analysis begins by ruling outdifferences in technology as the source of those disparities and confirms that standard hypothesesin organizational economics, which have been shown to explain the choice of organizational form inUS industry, also apply in Europe. We then argue that the preference for subcontracting oververtical integration in Europe is the result of European institutions particularly, labor regulationand tax laws that increase the costs of vertical integration.
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Payoff heterogeneity weakens positive feedback in binary choice models intwo ways. First, heterogeneity drives individuals to corners where theyare unaffected by strategic complementarities. Second, aggregate behaviouris smoother than individual behaviour when individuals are heterogeneous.However, this smoothing does not necessarily eliminate positive feedbackor guarantee a unique equilibrium. In games with an unbounded, continuouschoice space, heterogeneity may either weaken or strengthen positive feedback,depending on a simple convexity/concavity condition. We conclude that positivefeedback phenomena derived in representative agent models will often be robustto heterogeneity.
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This work studies the organization of less-than-truckload trucking from a contractual point of view. We show that the huge number of owner-operators working in the industry hides a much less fragmented reality. Most of those owner-operators are quasi-integrated in higher organizational structures. This hybrid form is generally more efficient than vertical integration because, in the Spanish institutional environment, it lessens serious moral hazard problems, related mainly to the use of the vehicles, and makes it possible to reach economies of scale and density. Empirical evidence suggests that what leads organizations to vertically integrate is not the presence of such economies but hold-up problems, related to the existence of specific assets. Finally, an international comparison hints that institutional constraints are able to explain differences in the evolution of vertical integration across countries.
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The Drivers Scheduling Problem (DSP) consists of selecting a set of duties for vehicle drivers, for example buses, trains, plane or boat drivers or pilots, for the transportation of passengers or goods. This is a complex problem because it involves several constraints related to labour and company rules and can also present different evaluation criteria and objectives. Being able to develop an adequate model for this problem that can represent the real problem as close as possible is an important research area.The main objective of this research work is to present new mathematical models to the DSP problem that represent all the complexity of the drivers scheduling problem, and also demonstrate that the solutions of these models can be easily implemented in real situations. This issue has been recognized by several authors and as important problem in Public Transportation. The most well-known and general formulation for the DSP is a Set Partition/Set Covering Model (SPP/SCP). However, to a large extend these models simplify some of the specific business aspects and issues of real problems. This makes it difficult to use these models as automatic planning systems because the schedules obtained must be modified manually to be implemented in real situations. Based on extensive passenger transportation experience in bus companies in Portugal, we propose new alternative models to formulate the DSP problem. These models are also based on Set Partitioning/Covering Models; however, they take into account the bus operator issues and the perspective opinions and environment of the user.We follow the steps of the Operations Research Methodology which consist of: Identify the Problem; Understand the System; Formulate a Mathematical Model; Verify the Model; Select the Best Alternative; Present the Results of theAnalysis and Implement and Evaluate. All the processes are done with close participation and involvement of the final users from different transportation companies. The planner s opinion and main criticisms are used to improve the proposed model in a continuous enrichment process. The final objective is to have a model that can be incorporated into an information system to be used as an automatic tool to produce driver schedules. Therefore, the criteria for evaluating the models is the capacity to generate real and useful schedules that can be implemented without many manual adjustments or modifications. We have considered the following as measures of the quality of the model: simplicity, solution quality and applicability. We tested the alternative models with a set of real data obtained from several different transportation companies and analyzed the optimal schedules obtained with respect to the applicability of the solution to the real situation. To do this, the schedules were analyzed by the planners to determine their quality and applicability. The main result of this work is the proposition of new mathematical models for the DSP that better represent the realities of the passenger transportation operators and lead to better schedules that can be implemented directly in real situations.
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This paper extends the theory of network competition betweentelecommunications operators by allowing receivers to derive a surplusfrom receiving calls (call externality) and to affect the volume ofcommunications by hanging up (receiver sovereignty). We investigate theextent to which receiver charges can lead to an internalization of thecalling externality. When the receiver charge and the termination(access) charge are both regulated, there exists an e±cient equilibrium.Effciency requires a termination discount. When reception charges aremarket determined, it is optimal for each operator to set the prices foremission and reception at their off-net costs. For an appropriately chosentermination charge, the symmetric equilibrium is again effcient. Lastly,we show that network-based price discrimination creates strong incentivesfor connectivity breakdowns, even between equal networks.
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The objective of this study was the identification of the attributes and dimensions of service quality affecting the service performance of the five stars resort hotels located in the Cape Verde Islands. The reason boosting the initiative to do this research was the paramount role of the resort hotels in the development of the travel and tourism sector in Cape Verde, and the impact that today this sector has had in the economy of that country. The research opens with a literature review on the service quality theory in the hotel industry, starting from the middle of the 1980s with the classic model of service quality and SERVQUAL instrument to the analysis of recent models of service quality measurement in the hotel industry, as it is an example the scale of items developed in 2003 in the Lodging Quality Index (LQI). Furthermore, the study elaborates an analysis on the importance of the travel and tourism activities in the Cape Verde Islands, and it evidences the enormous importance of those activities in the performance of the Cape Verdean hotel industry. In sequence the study analyzes in details the hotel industry of Cape Verde and it identifies the market size of the five stars resort hotels and their current operators in that market. Moreover, the research develops with an online questionnaire elaborated and sent through the platforms of travel websites and communities to the guests whom have experienced the service of the five stars resort hotels located in the Cape Verde Islands. The scope of the questionnaire was to assess the attributes and dimensions of service quality in the five stars resort hotels of Cape Verde. The results of the questionnaire were in sequence analyzed through descriptive and applied statistics, using Microsoft Excel and the Statistical Package for Social Science (SPSS). Content validity analysis, factor analysis, and reliability analysis of the factors were made to purify an initial scale of 47 items of service quality. An instrument with three dimensions covering twenty four attributes of service quality assessment in the five stars resort hotels of Cape Verde was finally created. The three dimensions found were: staff competence; food and entertainment; and physical facilities. This study on the service in the five stars resort hotels of Cape Verde ends with brief comments on the status of service quality according to the identified dimensions and their attributes. In the conclusion, the study summarizes the whole work and gives some directions for future research.
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The Barge Terminal Directory has been prepared by the Iowa Department of Transportation’s Modal Division to provide quick access to information on Iowa’s river terminals and fleeting/harbor services. The information is to assist those who may need barge transportation services. The information in the directory was provided by the terminal operators. The Modal Division would appreciate any help on corrections, additions or deletions.
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Bicycling, once considered a recreational activity for the young, has suddenly become a popular means of transportation for adults. The recent rise in fuel costs, an increased interest in physical fitness and concern for the environment have resulted in a growing number of adults choosing to commute by bike. The benefits of commuting by bicycle are numerous, and include saving money, promoting good health and energy conservation. However, the combination of bicycles and motor vehicles on public roads is not always a pleasant experience. Increasing numbers of cyclists on city streets lead to increased conflicts with motor vehicles and can endanger both vehicle operators.