970 resultados para Error in essence


Relevância:

90.00% 90.00%

Publicador:

Resumo:

Building designs regularly fail to achieve the anticipated levels of in-use energy consumption. The interaction of occupants with building controls is often cited as a key factor behind this discrepancy. This paper examines whether one factor in inadvertent energy consumption might be the appearance of post-completion errors (when an intended action is not taken because a primary goal has already been accomplished) in occupants’ interactions with building controls. Post-completion errors have been widely studied in human-computer interaction but the concept has not previously been applied to the interaction of occupants with building controls. Two experiments were carried out to examine the effect of incorporating two different types of simple prompt to reduce post-completion error in the use of light switches in office meeting rooms. Results showed that the prompts were effective and that occupants switched off lights when leaving the room more often when presented with a normative prompt than with a standard injunction. Additionally, an over reliance on PIR sensors to turn off lights after meetings was observed, which reduced their intended energy savings. We conclude that achieving low carbon buildings in practice is not solely a technological issue and that application of user-models from human-computer interaction will encourage appropriate occupant interaction with building controls and help reduce inadvertent energy consumption.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

For certain observing types, such as those that are remotely sensed, the observation errors are correlated and these correlations are state- and time-dependent. In this work, we develop a method for diagnosing and incorporating spatially correlated and time-dependent observation error in an ensemble data assimilation system. The method combines an ensemble transform Kalman filter with a method that uses statistical averages of background and analysis innovations to provide an estimate of the observation error covariance matrix. To evaluate the performance of the method, we perform identical twin experiments using the Lorenz ’96 and Kuramoto-Sivashinsky models. Using our approach, a good approximation to the true observation error covariance can be recovered in cases where the initial estimate of the error covariance is incorrect. Spatial observation error covariances where the length scale of the true covariance changes slowly in time can also be captured. We find that using the estimated correlated observation error in the assimilation improves the analysis.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

We present a novel method for retrieving high-resolution, three-dimensional (3-D) nonprecipitating cloud fields in both overcast and broken-cloud situations. The method uses scanning cloud radar and multiwavelength zenith radiances to obtain gridded 3-D liquid water content (LWC) and effective radius (re) and 2-D column mean droplet number concentration (Nd). By using an adaption of the ensemble Kalman filter, radiances are used to constrain the optical properties of the clouds using a forward model that employs full 3-D radiative transfer while also providing full error statistics given the uncertainty in the observations. To evaluate the new method, we first perform retrievals using synthetic measurements from a challenging cumulus cloud field produced by a large-eddy simulation snapshot. Uncertainty due to measurement error in overhead clouds is estimated at 20% in LWC and 6% in re, but the true error can be greater due to uncertainties in the assumed droplet size distribution and radiative transfer. Over the entire domain, LWC and re are retrieved with average error 0.05–0.08 g m-3 and ~2 μm, respectively, depending on the number of radiance channels used. The method is then evaluated using real data from the Atmospheric Radiation Measurement program Mobile Facility at the Azores. Two case studies are considered, one stratocumulus and one cumulus. Where available, the liquid water path retrieved directly above the observation site was found to be in good agreement with independent values obtained from microwave radiometer measurements, with an error of 20 g m-2.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

We use the elliptic reconstruction technique in combination with a duality approach to prove a posteriori error estimates for fully discrete backward Euler scheme for linear parabolic equations. As an application, we combine our result with the residual based estimators from the a posteriori estimation for elliptic problems to derive space-error indicators and thus a fully practical version of the estimators bounding the error in the $ \mathrm {L}_{\infty }(0,T;\mathrm {L}_2(\varOmega ))$ norm. These estimators, which are of optimal order, extend those introduced by Eriksson and Johnson in 1991 by taking into account the error induced by the mesh changes and allowing for a more flexible use of the elliptic estimators. For comparison with previous results we derive also an energy-based a posteriori estimate for the $ \mathrm {L}_{\infty }(0,T;\mathrm {L}_2(\varOmega ))$-error which simplifies a previous one given by Lakkis and Makridakis in 2006. We then compare both estimators (duality vs. energy) in practical situations and draw conclusions.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Ruminant production is a vital part of food industry but it raises environmental concerns, partly due to the associated methane outputs. Efficient methane mitigation and estimation of emissions from ruminants requires accurate prediction tools. Equations recommended by international organizations or scientific studies have been developed with animals fed conserved forages and concentrates and may be used with caution for grazing cattle. The aim of the current study was to develop prediction equations with animals fed fresh grass in order to be more suitable to pasture-based systems and for animals at lower feeding levels. A study with 25 nonpregnant nonlactating cows fed solely fresh-cut grass at maintenance energy level was performed over two consecutive grazing seasons. Grass of broad feeding quality, due to contrasting harvest dates, maturity, fertilisation and grass varieties, from eight swards was offered. Cows were offered the experimental diets for at least 2 weeks before housed in calorimetric chambers over 3 consecutive days with feed intake measurements and total urine and faeces collections performed daily. Methane emissions were measured over the last 2 days. Prediction models were developed from 100 3-day averaged records. Internal validation of these equations, and those recommended in literature, was performed. The existing in greenhouse gas inventories models under-estimated methane emissions from animals fed fresh-cut grass at maintenance while the new models, using the same predictors, improved prediction accuracy. Error in methane outputs prediction was decreased when grass nutrient, metabolisable energy and digestible organic matter concentrations were added as predictors to equations already containing dry matter or energy intakes, possibly because they explain feed digestibility and the type of energy-supplying nutrients more efficiently. Predictions based on readily available farm-level data, such as liveweight and grass nutrient concentrations were also generated and performed satisfactorily. New models may be recommended for predictions of methane emissions from grazing cattle at maintenance or low feeding levels.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Phylogenetic comparative methods are increasingly used to give new insights into the dynamics of trait evolution in deep time. For continuous traits the core of these methods is a suite of models that attempt to capture evolutionary patterns by extending the Brownian constant variance model. However, the properties of these models are often poorly understood, which can lead to the misinterpretation of results. Here we focus on one of these models – the Ornstein Uhlenbeck (OU) model. We show that the OU model is frequently incorrectly favoured over simpler models when using Likelihood ratio tests, and that many studies fitting this model use datasets that are small and prone to this problem. We also show that very small amounts of error in datasets can have profound effects on the inferences derived from OU models. Our results suggest that simulating fitted models and comparing with empirical results is critical when fitting OU and other extensions of the Brownian model. We conclude by making recommendations for best practice in fitting OU models in phylogenetic comparative analyses, and for interpreting the parameters of the OU model.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Objective Underreporting of energy intake is prevalent in food surveys, but there is controversy about which dietary assessment method provides greater underreporting rates. Our objective is to compare validity of self-reported energy intake obtained by three dietary assessment methods with total energy expenditure (TEE) obtained by doubly labeled water (DLW) among Brazilian women. Design We used a cross-sectional study. Subjects/setting Sixty-five females aged 18 to 57 years (28 normal-weight, 10 over-weight, and 27 obese) were recruited from two universities to participate. Main outcome measures TEE determined by DLW, energy intake estimated by three 24-hour recalls, 3-day food record, and a food frequency questionnaire (FFQ). Statistical analyses performed Regression and analysis of variance with repeated measures compared TEE and energy intake values, and energy intake-to-TEE ratios and energy intake-TEE values between dietary assessment methods. Bland and Altman plots were provided for each method. chi(2) test compared proportion of underreporters between the methods. Results Mean TEE was 2,622 kcal (standard deviation [SD] =490 kcal), while mean energy intake was 2,078 kcal (SD=430 kcal) for the diet recalls; 2,044 kcal (SD=479 kcal) for the food record and 1,984 kcal (SD=832 kcal) for the FFQ (all energy intake values significantly differed from TEE; P<0.0001). Bland and Altman plots indicated great dispersion, negative mean differences between measurements, and wide limits of agreement. Obese subjects underreported more than normal-weight subjects in the diet recalls and in the food records, but not in the FFQ. Years of education, income and ethnicity were associated with reporting accuracy. Conclusions The FFQ produced greater under- and overestimation of energy intake. Underreporting of energy intake is a serious and prevalent error in dietary self-reports provided by Brazilian women, as has been described in studies conducted in developed countries.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Skew-normal distribution is a class of distributions that includes the normal distributions as a special case. In this paper, we explore the use of Markov Chain Monte Carlo (MCMC) methods to develop a Bayesian analysis in a multivariate, null intercept, measurement error model [R. Aoki, H. Bolfarine, J.A. Achcar, and D. Leao Pinto Jr, Bayesian analysis of a multivariate null intercept error-in -variables regression model, J. Biopharm. Stat. 13(4) (2003b), pp. 763-771] where the unobserved value of the covariate (latent variable) follows a skew-normal distribution. The results and methods are applied to a real dental clinical trial presented in [A. Hadgu and G. Koch, Application of generalized estimating equations to a dental randomized clinical trial, J. Biopharm. Stat. 9 (1999), pp. 161-178].

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Purpose: To examine whether physical activity logbooks influence estimates of validity of 7-d recall physical activity questionnaires. Methods: A  convenience sample of 551 adults aged 18–75 yr wore an MTI  accelerometer for seven consecutive days and were then randomly administered two of four 7-d recall physical activity questionnaires that varied in length and format (Active Australia Survey (AAS), long and short  International Physical Activity Questionnaires (IPAQ-L and IPAQ-S), and Behavioral Risk Factor Surveillance System (BRFSS)). A subsample of 75% concurrently completed a physical activity logbook. Results: Correlations (rho) between self-reported and measured duration of moderate- and vigorous-intensity activity and total activity were similar among participants who received a logbook and those who did not for each of the four instruments. There was also no interaction between assessment method (survey, accelerometer) and the assignment of a logbook. For the IPAQ-L, however, variability in the difference between accelerometer data and responses to the vigorous items was smaller among those assigned a logbook (F = 4.128, df = 260, P = 0.043). Overall, there were no differences in percent agreement or kappa for participation in sufficient levels of physical activity according to receipt of a logbook for any of the surveys. Conclusion: The process of self-monitoring through completion of a logbook does not appear to influence estimates of validity for brief or long questionnaires with global questions. Whereas the magnitude of error in accuracy of recall of particular types of activity may be reduced by completion of a logbook that is similar in structure to the survey being validated, this does not appear to influence overall estimates of validity.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

A major issue confronting educators is the extent to which they wish to conform to so-called paradigm shifts in teaching and learning. In the contemporary world of tertiary education these shifts embrace both pedagogy (from instructivist to constructivist) and technology (classroom to online). As teachers and learners are faced with the potential of these new learning environments, the extent to which the learning outcomes are achieved remains a high priority and subject to a wide range of evaluation strategies. Conventionally, evaluation is often conceptualised as occurring at the end of the development process, to assess first (formatively) whether or not the creative effort has achieved the original product goals and second (summatively) whether or not the desired learning outcomes were achieved. However, in the context of imperatives to implement online learning paradigms, the level of understanding teachers and developers have of the medium can impact the effectiveness of the product. This paper presents an additional perspective to the post-development, reactive evaluation processes in proposing the concept of proactive evaluation, a framework that identifies critical online learning factors and influences to better inform the development of learning resources. In essence, the proposal advocates an approach where development is undertaken within an environment where all activities are assessed using the evaluation criteria that would be applied when the product is assessed reactively. By performing these checks proactively, online learning resources will, in principle, work first time as all relevant factors and issues will have been considered and resolved.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

We, as librarians, are adept at challenging academics, students and administrators about the crucial role of information literacy in higher education and lifelong learning. Consequently, the push for strategic partnerships with academics is frequently in the foreground of our thinking. Concomitantly, the push for academic status for librarians is raised occasionally, particularly as a pay and equity issue. Yet, our purposes may appear somewhat misguided or rhetorical when contrasted to the nominal prerequisites required for professional practice, especially when compared with those of academics. The issues of information literacy and knowledge production within a knowledge economy compound such debate. This paper argues that ‘credential creep’ is catching up with librarians in the university sector. In order to be regarded as integral to academic endeavour, those of us who ‘teach’ information literacy may need to match the qualifications normally required by academics. Consonant with this proposal is the Australian and New Zealand Information Literacy Framework: Principles, Standards and Practice (Bundy, 2004) of the Australian and New Zealand Institute for Information Literacy (ANZIIL) and the Council of Australian University Librarians (CAUL). The Framework mirrors many of the desired outcomes of a doctoral degree, a degree possessed by approximately one per cent of Australian librarians but, in comparison, by more than fi fty-four per cent of Australian academics. This paper challenges—not academics—but librarians, to embrace the notion of undertaking doctoral study to enhance our professional (or amateur) practice and our information literacy. The recommendation is derived in essence from my study on doctoral research and information literacy (Macauley, 2001). It also incorporates the current discourse on these issues and uses personal narrative to articulate the findings. It seeks also to explore those tensions and contradictions commensurate with practising what we preach.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

In 1998, Maafahi Island was leased by the Maldives government to a private company for development as a multi-faceted primary production value-adding project. The project included boat building, agriculture and fish processing. As part of the agriculture project, a hydroponics facility was commenced in 2001, using a novel zero-runoff nutrient system. Virtually no information was available for using this system in tropical conditions; however Deakin University had been undertaking research on the system for tomato production. In 2004, two Deakin scientists visited the island with the specific purpose of assisting the project operators to ‘improve the greenhouse conditions’ and optimise the production from the greenhouse. In essence, the transition to successful production from ‘book learning’ and ‘no practical experience’ was found to be limited by a range of constraints, and demonstrated that a little knowledge is no substitute for a multidisciplinary approach. Progress had come to a standstill, not because of lack of horticultural expertise, but because of lack of understanding of fundamental science, and lack of understanding by equipment suppliers of the requirements imposed by the conditions.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

The lack of attention to quality control by house builders in the Australian State of Victoria has been a contentious issue for more than two decades. Ina an attempt to improve the quality of housing, various mechanisms such as voluntary and compulsory registration schemes have been adopted and discarded by industry-based organisations and government. While builders are encouraged to improve construction quality, little is known and published about the quality of housing produced by owner builders specifically during the seven year warranty period after construction is completed. With this in mind, this thesis presents research findings that compare the latent defects in houses built by owner builders with those of registered builders. Using inspection reports provided by Archicentre Institute of Architects> a sample of 1772 houses, of which 1002 were owner builders and 770 were registered builders


was used to determine the severity, the incidence, and location of defects within each house type. Houses less than a year old were found to contain a siginificant proportion of defects for both types of builder. In addition, it was found that HO builders had a mean of 2.74 defects per house and HR builders mean of 2.30 defects per house for the seven-year warranty period. To determine whether there was a significant difference between the quality of housing produced by HO and HR the statistical technique of Chi-squared analysis was undertaken at a 5% level of significance. The analysis revealed that there was a significant difference between the quality of housing procured by owner and registered
builders. In particular, it was found that the important category of workmanship for HO builders had significantly less defects that HR builders, which suggests that HR builders need to improve their managerial practices and the quality of on-site supervision. In essence, this thesis has provided a series of benchmark metrics for latent defects against which current and future legislative programs con be compared for new housing in the State of Victoria. It is recommended that future research focus on the methods for improving the role of the on-site supervisor as they are considered to be the important link in the quality chain.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Use of New Product Development (NPD) methods may benefit New Zealand SMEs and entrepreneurial firms in gaining greater market share. In this paper we review the literature on New Product Development, NPD theory and methods for early stage product design and development. Our reading suggests that product design has greater success when the customer is involved in the design effort. It also recommends methods of approach to new markets in the (NPD) life cycle. The literature further elucidates methods for identification of product design criteria based on customer needs identification. In essence, customer-product interaction in the early stages of product development is important to product success in new markets for entrepreneurial firms and SMEs. Of particular interest are early-stage NPD research methods and their influence on the company’s marketing strategy.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

It is only in recent times that the magnitude of Ancient Mesopotamia’s contribution to language, agriculture, modern thought and urbane society has begun to be understood. Most relevant to this study is the governance of Mesopotamia’s early city-states by a political system that Jacobsen has termed ‘Primitive Democracy’ where “…ultimate political power rested with a general assembly of all adult freemen” (Jacobsen, 1977; 128). Yet, despite this, the coverage of Iraq in the Western media since its creation at the end of the First World War and particularly since the first Gulf War, has tended towards Orientalism (Said, 1978) by trivialising this nation and thereby reinforcing the hegemony of the West over the ‘backward, barbaric’ East.

This paper examines this issue further by comparing and contrasting the representations of the Iraqi election of January 30, 2005 in four of Australia’s leading daily newspapers (The Australian, The Courier-Mail, The Age and The Sydney Morning Herald) with four Middle Eastern English language papers (The Daily Star from Lebanon, Andolu Agency and Dunya both based in Turkey, and the eponymous Kuwait Times). In essence, it finds that while the Australian media posits democracy as a Western concept and asserts a discourse of US hegemony, the Middle Eastern papers are more contemplative, focusing on the impact that this election could have throughout the region.