978 resultados para Reliability management


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BACKGROUND: We investigated the psychometric properties of a short questionnaire for combined assessment of different perceived stress management skills in the general population and tested whether scores relate to physiological stress reactivity. METHODS: For psychometric evaluation, we determined the factor structure of the questionnaire and investigated its measurement invariance in the participant groups and over time in three different independent samples representing the general population (total N=332). Reliability was tested by estimating test-retest reliability, internal consistency, and item reliabilities. We examined convergent and criterion validity using selected criterion variables. For endocrine validation, 35 healthy non-smoking and medication-free men in a laboratory study and 35 male and female employees in a workplace study underwent an acute standardized psychosocial stress task. We assessed stress management skills and measured salivary cortisol before and several times up to 60 min (workplace study) and 120 min (laboratory study) after stress. Potential confounders were controlled. RESULTS: The factor structure of the questionnaire consists of five scales reflecting acceptably distinct stress management skills such as cognitive strategies, use of social support, relaxation strategies, anger regulation, and perception of bodily tension. This factor structure was stable across participant groups and over time. Internal consistencies, item reliabilities, and test-retest reliabilities met established statistical requirements. Convergent and criterion validity were also established. In both endocrine validation studies, higher stress management skills were independently associated with lower cortisol stress reactivity (p's<.029). CONCLUSIONS: Our findings suggest that the questionnaire has good psychometric properties and that it relates to subjective psychological and objective physiological stress indicators. Therefore, the instrument seems a suitable measure for differential assessment of stress management skills in the general population.

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BackgroundThe aim of the present study was to evaluate the feasibility of using a telephone survey in gaining an understanding of the possible herd and management factors influencing the performance (i.e. safety and efficacy) of a vaccine against porcine circovirus type 2 (PCV2) in a large number of herds and to estimate customers¿ satisfaction.ResultsDatasets from 227 pig herds that currently applied or have applied a PCV2 vaccine were analysed. Since 1-, 2- and 3-site production systems were surveyed, the herds were allocated in one of two subsets, where only applicable variables out of 180 were analysed. Group 1 was comprised of herds with sows, suckling pigs and nursery pigs, whereas herds in Group 2 in all cases kept fattening pigs. Overall 14 variables evaluating the subjective satisfaction with one particular PCV2 vaccine were comingled to an abstract dependent variable for further models, which was characterized by a binary outcome from a cluster analysis: good/excellent satisfaction (green cluster) and moderate satisfaction (red cluster). The other 166 variables comprised information about diagnostics, vaccination, housing, management, were considered as independent variables. In Group 1, herds using the vaccine due to recognised PCV2 related health problems (wasting, mortality or porcine dermatitis and nephropathy syndrome) had a 2.4-fold increased chance (1/OR) of belonging to the green cluster. In the final model for Group 1, the diagnosis of diseases other than PCV2, the reason for vaccine administration being other than PCV2-associated diseases and using a single injection of iron had significant influence on allocating into the green cluster (P¿<¿0.05). In Group 2, only unchanged time or delay of time of vaccination influenced the satisfaction (P¿<¿0.05).ConclusionThe methodology and statistical approach used in this study were feasible to scientifically assess ¿satisfaction¿, and to determine factors influencing farmers¿ and vets¿ opinion about the safety and efficacy of a new vaccine.

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Self-management is being promoted in cystic fibrosis (CF). However, it has not been well studied. Principal aims of this research were (1) to evaluate psychometric properties of a CF disease status measure, the NIH Clinical Score; (2) to develop and validate a measure of self-management behavior, the SMQ-CF scale, and (3) to examine the relation between self-management and disease status in CF patients over two years.^ In study 1, NIH Clinical Scores for 200 patients were used. The scale was examined for internal consistency, interrater reliability, and content validity using factor analysis. The Cronbach's alpha (.81) and interrater reliability (.90) for the total scale were high. General scale items were less reliable. Factor analysis indicated that most of the variance in disease status is accounted for by Factor 1 which consists of pulmonary disease items.^ The SMQ-CF measures the performance of CF self-management. Pilot testing was done with 98 CF primary caregivers. Internal consistency reliability, social desirability bias, and content validity using factor analysis were examined. Internal consistency was good (alpha =.95). Social desirability correlation was low (r =.095). Twelve factors identified were consistent with conceptual groupings of behaviors. Around two hundred caregivers from two CF centers were surveyed and multivariate analysis of variance was used to assess construct validity. Results confirmed expected relations between self-management, patient age, and disease status. Patient age accounted for 50% and disease status 18% of the variance in the SMQ-CF scale.^ It was hypothesized that self-management would positively affect future disease status. Data from 199 CF patients (control and education intervention groups) were examined. Models of hypothesized relations were tested using LISREL structural equation modeling. Results indicated that the relations between baseline self-management and Time 1 disease status were not significant. Significant relations were observed in self-management behaviors from time 1 to time 2 and patterns of significant relations differed between the two groups.^ This research has contributed to refinements in the ability to measure self-management behavior and disease status outcomes in cystic fibrosis. In addition, it provides the first steps in exploratory behavioral analysis with regard to self-management in this disease. ^

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The use of cloud computing is extending to all kind of systems, including the ones that are part of Critical Infrastructures, and measuring the reliability is becoming more difficult. Computing is becoming the 5th utility, in part thanks to the use of cloud services. Cloud computing is used now by all types of systems and organizations, including critical infrastructure, creating hidden inter-dependencies on both public and private cloud models. This paper investigates the use of cloud computing by critical infrastructure systems, the reliability and continuity of services risks associated with their use by critical systems. Some examples are presented of their use by different critical industries, and even when the use of cloud computing by such systems is not widely extended, there is a future risk that this paper presents. The concepts of macro and micro dependability and the model we introduce are useful for inter-dependency definition and for analyzing the resilience of systems that depend on other systems, specifically in the cloud model.

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Teamwork, is one of the abilities that today is highly valued in the professional arena with a great importance for various personal and interpersonal skills associated with it. In this context, the Technical University of Madrid, is developing a coordinated educational innovation project, which main objective is to develop methodological and assessment tools for the acquisition of personal skills necessary to improve the employability of graduates and their skills for project management. Within this context, this paper proposes a methodology composed of various activities and indicators, as well as specific assessment instruments linked to the teamwork competence. Through a series of systematic steps it was allowed the design of an instrument and construction of a scale for measuring the competence of teamwork. The practical application of the methodology has been carried out in Projects lectures from different Schools of Engineering at the Technical University of Madrid, which results are presented in this document as a pilot experience. Results show the various aspects and methods that teachers should consider in evaluating the competence of the work, including analysis of the quality of results, through reliability and construct validity. On the other hand, show the advantages of applying this methodology in the field of project management teaching.

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From the water management perspective, water scarcity is an unacceptable risk of facing water shortages to serve water demands in the near future. Water scarcity may be temporary and related to drought conditions or other accidental situation, or may be permanent and due to deeper causes such as excessive demand growth, lack of infrastructure for water storage or transport, or constraints in water management. Diagnosing the causes of water scarcity in complex water resources systems is a precondition to adopt effective drought risk management actions. In this paper we present four indices which have been developed to evaluate water scarcity. We propose a methodology for interpretation of index values that can lead to conclusions about the reliability and vulnerability of systems to water scarcity, as well as to diagnose their possible causes and to propose solutions. The described methodology was applied to the Ebro river basin, identifying existing and expected problems and possible solutions. System diagnostics, based exclusively on the analysis of index values, were compared with the known reality as perceived by system managers, validating the conclusions in all cases

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In this paper, a reliability analysis of a photovoltaic rural electrification (PVRE) programme is proposed considering the failures in the 13 000 installed Solar Home System (SHS) devices occurring over a long operating period of 5 years. A previous arrangement of the database and a brief explanation of the reliability concepts will serve to introduce the failure distribution of every component, from which the SHS lifetime operating features will be described. An application example will show the usefulness of the obtained results in the forecasting of spare parts during the maintenance period. The conclusions of this study may be useful in the scientific design of PVRE programme maintenance structures, with the goal of shedding some light on the technical management mechanisms in decentralised rural electrification.

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The main goal of this proposal is to join together the owners of the most advanced CPV technology, with respect to the state of the art, in order to research from its leading position new applications for CPV systems. In addition to opening up new markets, it will unveil possible sources of failure in new environments outside Europe, in order to assure component reliability. The proposed project will also try to improve the current technology of the industrial partners (ISOFOTON and CONCENTRIX) by accelerating the learning curve that CPV must follow in order to reach the competitive market, and lowering the cost under the current flat panel PV significantly within 3-4 years. The use of CPV systems in remote areas, together with harsher radiation, ambient and infrastructure conditions will help to increase the rate of progress of this technology. In addition, the ISFOC s contribution, which brings together seven power plants from seven CPV technologies up to 3 MWpeak, will allow creating the most complete database of components and systems performance to be generated as well as the effects of radiation and meteorology on systems operations. Finally, regarding the new applications for CPV subject, the project will use a CPV system sized 25 kWp in a stand-alone station in Egypt (NWRC) for the first time for water pumping and irrigation purposes. In a similar way ISOFOTON will connect up to 25 kWp CPV to the Moroccan ONE utility grid. From the research content point of view of this project, which is directly addressed by the scope of the call, the cooperative research between UPM, FhG-ISE and the two companies will be favoured by the fact that all are progressing in similar directions: developing two-stage optics CPV systems. In addition to these technology improvements the UPM is very interested in developing a new concept of module, recently patented, which will fulfil all required characteristics of a good CPV with less components and reducing cost.

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There is remarkable growing concern about the quality control at the time, which has led to the search for methods capable of addressing effectively the reliability analysis as part of the Statistic. Managers, researchers and Engineers must understand that 'statistical thinking' is not just a set of statistical tools. They should start considering 'statistical thinking' from a 'system', which means, developing systems that meet specific statistical tools and other methodologies for an activity. The aim of this article is to encourage them (engineers, researchers and managers) to develop a new way of thinking.

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Operalion and mainlenance (O&M) casi 01 solar home syslems (SHS) in pholovollaie rural electrification (PVRE) programmes is a key factor in the economic viability and long lerm suslainability. This paper reports on a 13000 inslalled SHSs programme carried oul in Moroceo. Il is presenled Ihe reliability analysis 01 Ihe SHSs as well as the distribution of real cests of installation, O&M and management to oblain respeclively Ihe reliability lunelions 01 Ihe SHS componenls and lo eharaclerize the overall programme cast structure.

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The aim of the paper is to discuss the use of knowledge models to formulate general applications. First, the paper presents the recent evolution of the software field where increasing attention is paid to conceptual modeling. Then, the current state of knowledge modeling techniques is described where increased reliability is available through the modern knowledge acquisition techniques and supporting tools. The KSM (Knowledge Structure Manager) tool is described next. First, the concept of knowledge area is introduced as a building block where methods to perform a collection of tasks are included together with the bodies of knowledge providing the basic methods to perform the basic tasks. Then, the CONCEL language to define vocabularies of domains and the LINK language for methods formulation are introduced. Finally, the object oriented implementation of a knowledge area is described and a general methodology for application design and maintenance supported by KSM is proposed. To illustrate the concepts and methods, an example of system for intelligent traffic management in a road network is described. This example is followed by a proposal of generalization for reuse of the resulting architecture. Finally, some concluding comments are proposed about the feasibility of using the knowledge modeling tools and methods for general application design.

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The Smartcity Málaga project is one of Europe?s largest ecoefficient city initiatives. The project has implemented a field trial in 50 households to study the effects of energy monitoring and management technologies on the residential electricity consumption. This poster presents some lessons learned on energy consumption trends, smart clamps reliability and the suitability of power contracted by users, obtained after six months of data analysis.

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Most of the modem developments with classification trees are aimed at improving their predictive capacity. This article considers a curiously neglected aspect of classification trees, namely the reliability of predictions that come from a given classification tree. In the sense that a node of a tree represents a point in the predictor space in the limit, the aim of this article is the development of localized assessment of the reliability of prediction rules. A classification tree may be used either to provide a probability forecast, where for each node the membership probabilities for each class constitutes the prediction, or a true classification where each new observation is predictively assigned to a unique class. Correspondingly, two types of reliability measure will be derived-namely, prediction reliability and classification reliability. We use bootstrapping methods as the main tool to construct these measures. We also provide a suite of graphical displays by which they may be easily appreciated. In addition to providing some estimate of the reliability of specific forecasts of each type, these measures can also be used to guide future data collection to improve the effectiveness of the tree model. The motivating example we give has a binary response, namely the presence or absence of a species of Eucalypt, Eucalyptus cloeziana, at a given sampling location in response to a suite of environmental covariates, (although the methods are not restricted to binary response data).

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Consider a network of unreliable links, modelling for example a communication network. Estimating the reliability of the network-expressed as the probability that certain nodes in the network are connected-is a computationally difficult task. In this paper we study how the Cross-Entropy method can be used to obtain more efficient network reliability estimation procedures. Three techniques of estimation are considered: Crude Monte Carlo and the more sophisticated Permutation Monte Carlo and Merge Process. We show that the Cross-Entropy method yields a speed-up over all three techniques.