924 resultados para index method


Relevância:

20.00% 20.00%

Publicador:

Resumo:

An analytical method for the detection of carbonaceous gases by a non-dispersive infrared sensor (NDIR) has been developed. The calibration plots of six carbonaceous gases including CO2, CH4, CO, C2H2, C2H4 and C2H6 were obtained and the reproducibility determined to verify the feasibility of this gas monitoring method. The results prove that squared correlation coefficients for the six gas measurements are greater than 0.999. The reproducibility is excellent, thus indicating that this analytical method is useful to determinate the concentrations of carbonaceous gases.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Throughout the Asia Pacific Economic Cooperation (APEC) and across the world, riders and passengers of motorcycles and scooters are among the most vulnerable road users. Such vulnerability is especially pertinent for nations that more often use motorcycles and scooters as a method of transportation. In developing effective countermeasures to reduce motorcycle and scooter death and injury across multiple regions, consideration is required of various situational and socio-cultural factors that vary across APEC economies. This compendium aims to facilitate implementation of best practice countermeasures to improve motorcycle safety in APEC member economies.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Transient hyperopic refractive shifts occur on a timescale of weeks in some patients after initiation of therapy for hyperglycemia, and are usually followed by recovery to the original refraction. Possible lenticular origin of these changes is considered in terms of a paraxial gradient index model. Assuming that the lens thickness and curvatures remain unchanged, as observed in practice, it appears possible to account for initial hyperopic refractive shifts of up to a few diopters by reduction in refractive index near the lens center and alteration in the rate of change between center and surface, so that most of the index change occurs closer to the lens surface. Restoration of the original refraction depends on further change in the refractive index distribution with more gradual changes in refractive index from the lens center to its surface. Modeling limitations are discussed.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background: Decreased ability to perform Activities of Daily Living (ADLs) during hospitalisation has negative consequences for patients and health service delivery. Objective: To develop an Index to stratify patients at lower and higher risk of a significant decline in ability to perform ADLs at discharge. Design: Prospective two cohort study comprising a derivation (n=389; mean age 82.3 years; SD� 7.1) and a validation cohort (n=153; mean age 81.5 years; SD� 6.1). Patients and setting: General medical patients aged = 70 years admitted to three university-affiliated acute care hospitals in Brisbane, Australia. Measurement and main results: The short ADL Scale was used to identify a significant decline in ability to perform ADLs from premorbid to discharge. In the derivation cohort, 77 patients (19.8%) experienced a significant decline. Four significant factors were identified for patients independent at baseline: 'requiring moderate assistance to being totally dependent on others with bathing'; 'difficulty understanding others (frequently or all the time)'; 'requiring moderate assistance to being totally dependent on others with performing housework'; a 'history of experiencing at least one fall in the previous 90 days prior to hospital admission' in addition to 'independent at baseline', which was protective against decline at discharge. 'Difficulty understanding others (frequently or all the time)' and 'requiring moderate assistance to being totally dependent on others with performing housework' were also predictors for patients dependent in ADLs at baseline. Sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of the DADLD dichotomised risk scores were: 83.1% (95% CI 72.8; 90.7); 60.5% (95% CI 54.8; 65.9); 34.2% (95% CI 27.5; 41.5); 93.5% (95% CI 89.2; 96.5). In the validation cohort, 47 patients (30.7%) experienced a significant decline. Sensitivity, specificity, PPV and NPV of the DADLD were: 78.7% (95% CI 64.3; 89.3); 69.8% (95% CI 60.1, 78.3); 53.6% (95% CI 41.2; 65.7); 88.1% (95% CI 79.2; 94.1). Conclusions: The DADLD Index is a useful tool for identifying patients at higher risk of decline in ability to perform ADLs at discharge.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Purpose. The purpose of this article was to present methods capable of estimating the size and shape of the human eye lens without resorting to phakometry or magnetic resonance imaging (MRI). Methods. Previously published biometry and phakometry data of 66 emmetropic eyes of 66 subjects (age range [18, 63] years, spherical equivalent range [−0.75, +0.75] D) were used to define multiple linear regressions for the radii of curvature and thickness of the lens, from which the lens refractive index could be derived. MRI biometry was also available for a subset of 30 subjects, from which regressions could be determined for the vertex radii of curvature, conic constants, equatorial diameter, volume, and surface area. All regressions were compared with the phakometry and MRI data; the radii of curvature regressions were also compared with a method proposed by Bennett and Royston et al. Results. The regressions were in good agreement with the original measurements. This was especially the case for the regressions of lens thickness, volume, and surface area, which each had an R2 > 0.6. The regression for the posterior radius of curvature had an R2 < 0.2, making this regression unreliable. For all other regressions we found 0.25 < R2 < 0.6. The Bennett-Royston method also produced a good estimation of the radii of curvature, provided its parameters were adjusted appropriately. Conclusions. The regressions presented in this article offer a valuable alternative in case no measured lens biometry values are available; however care must be taken for possible outliers.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Restoring a large-scale power system has always been a complicated and important issue. A lot of research work has been done on different aspects of the whole power system restoration procedure. However, more time will be required to complete the power system restoration process in an actual situation if accurate and real-time system data cannot be obtained. With the development of the wide area monitoring system (WAMS), power system operators are capable of accessing to more accurate data in the restoration stage after a major outage. The ultimate goal of the system restoration is to restore as much load as possible while in the shortest period of time after a blackout, and the restorable load can be estimated by employing WAMS. Moreover, discrete restorable loads are employed considering the limited number of circuit-breaker operations and the practical topology of distribution systems. In this work, a restorable load estimation method is proposed employing WAMS data after the network frame has been reenergized, and WAMS is also employed to monitor the system parameters in case the newly recovered system becomes unstable again. The proposed method has been validated with the New England 39-Bus system and an actual power system in Guangzhou, China.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper presents the direct strength method (DSM) equations for cold-formed steel beams subject to shear. Light gauge cold-formed steel sections have been developed as more economical building solutions to the alternative heavier hot-rolled sections in the commercial and residential markets. Cold-formed lipped channel beams (LCB), LiteSteel beams (LSB) and hollow flange beams (HFB) are commonly used as flexural members such as floor joists and bearers. However, their shear capacities are determined based on conservative design rules. For the shear design of cold-formed web panels, their elastic shear buckling strength must be determined accurately including the potential post-buckling strength. Currently the elastic shear buckling coefficients of web panels are determined by assuming conservatively that the web panels are simply supported at the junction between the flange and web elements and ignore the post-buckling strength. Hence experimental and numerical studies were conducted to investigate the shear behaviour and strength of LSBs, LCBs and HFBs. New direct strength method (DSM) based design equations were proposed to determine the ultimate shear capacities of cold-formed steel beams. An improved equation for the higher elastic shear buckling coefficient of cold-formed steel beams was proposed based on finite element analysis results and included in the DSM design equations. A new post-buckling coefficient was also introduced in the DSM equation to include the available post-buckling strength of cold-formed steel beams.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Objective: Menopause is the consequence of exhaustion of the ovarian follicular pool. AMH, an indirect hormonal marker of ovarian reserve, has been recently proposed as a predictor for age at menopause. Since BMI and smoking status are relevant independent factors associated with age at menopause we evaluated whether a model including all three of these variables could improve AMH-based prediction of age at menopause. Methods: In the present cohort study, participants were 375 eumenorrheic women aged 19–44 years and a sample of 2,635 Italian menopausal women. AMH values were obtained from the eumenorrheic women. Results: Regression analysis of the AMH data showed that a quadratic function of age provided a good description of these data plotted on a logarithmic scale, with a distribution of residual deviates that was not normal but showed significant leftskewness. Under the hypothesis that menopause can be predicted by AMH dropping below a critical threshold, a model predicting menopausal age was constructed from the AMH regression model and applied to the data on menopause. With the AMH threshold dependent on the covariates BMI and smoking status, the effects of these covariates were shown to be highly significant. Conclusions: In the present study we confirmed the good level of conformity between the distributions of observed and AMH-predicted ages at menopause, and showed that using BMI and smoking status as additional variables improves AMH-based prediction of age at menopause.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

An online secondary path modelling method using a white noise as a training signal is required in many applications of active noise control (ANC) to ensure convergence of the system. Not continually injection of white noise during system operation makes the system more desirable. The purposes of the proposed method are two folds: controlling white noise by preventing continually injection, and benefiting white noise with a larger variance. The modelling accuracy and the convergence rate increase when a white noise with larger variance is used, however larger the variance increases the residual noise, which decreases performance of the system. This paper proposes a new approach for online secondary path modelling in feedfoward ANC systems. The proposed algorithm uses the advantages of the white noise with larger variance to model the secondary path, but the injection is stopped at the optimum point to increase performance of the system. Comparative simulation results shown in this paper indicate effectiveness of the proposed approach in controlling active noise.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this study is to develop a disclosure guide for climate-change-related corporate governance (CCCG) practices. Drawing from existing climate change policy guidelines together with content analysis of leading Australian companies’ disclosure practices, we develop a best practice index for the disclosure of CCCG practises. The best practice index is further informed, validated and refined by the contribution of experts from a range of stakeholder groups. Our index represents the most comprehensive list generated to date, utilising experts’ opinions, in relation to CCCG disclosure practices. This CCCG disclosure index would be useful for companies seeking to provide information in relation their CCCG practices

Relevância:

20.00% 20.00%

Publicador:

Resumo:

An investigation on hydrogen and methane sensing performance of hydrothermally formed niobium tungsten oxide nanorods employed in a Schottky diode structure is presented herein. By implementing tungsten into the surface of the niobium lattice, we create Nb5+ and W5+ oxide states and an abundant number of surface traps, which can collect and hold the adsorbate charge to reinforce a greater bending of the energy bands at the metal/oxide interface. We show experimentally, that extremely large voltage shifts can be achieved by these nanorods under exposure to gas at both room and high temperatures and attribute this to the strong accumulation of the dipolar charges at the interface via the surface traps. Thus, our results demonstrate that niobium tungsten oxide nanorods can be implemented for gas sensing applications, showing ultra-high sensitivities.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Bird communities were studied in two subregional areas of Cravens Peak, the Toko Plains and the Simpson-Strzelecki Dunefields, using the point counts method. A total of 42 2ha 20 minute surveys, 46 five-hundred metre radius area surveys and 170 5km drive through area surveys were conducted and observations made. Bird species were identified, counted and recorded. The data were compared in the two subregions and, as a whole, considering species groups according to land system on which the ecosystem occurs, the specific ecosystem and according to their general feeding habits (insectivore, omnivore, frugivore, granivore, nectarivore and carnivore). Species richness and species relative abundance were compared using Simpson’s Diversity Index and the data revealed that species are distributed largely on the basis of habitat. In general, areas with a greater number of vegetation strata recorded greater species diversity. Overall, the Tall Open Acacia georginae Shrubland on alluvial floodplains has a greater diversity of birds in a 2ha area (0.87, Simpson’s Index of Diversity 1-D) compared to the other survey sites.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper proposes a new method for online secondary path modeling in feedback active noise control (ANC) systems. In practical cases, the secondary path is usually time varying. For these cases, online modeling of secondary path is required to ensure convergence of the system. In literature the secondary path estimation is usually performed offline, prior to online modeling, where in the proposed system there is no need for using offline estimation. The proposed method consists of two steps: a noise controller which is based on an FxLMS algorithm, and a variable step size (VSS) LMS algorithm which is used to adapt the modeling filter with the secondary path. In order to increase performance of the algorithm in a faster convergence and accurate performance, we stop the VSS-LMS algorithm at the optimum point. The results of computer simulation shown in this paper indicate effectiveness of the proposed method.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

We directly constructed reduced graphene oxide–titanium oxide nanotube (RGO–TNT) film using a single-step, combined electrophoretic deposition–anodization (CEPDA) method. This method, based on the simultaneous anodic growth of tubular TiO2 and the electrophoretic-driven motion of RGO, allowed the formation of an effective interface between the two components, thus improving the electron transfer kinetics. Composites of these graphitic carbons with different levels of oxygen-containing groups, electron conductivity and interface reaction time were investigated; a fine balance of these parameters was achieved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper reports the results of a mixed method approach to answer: To what extent do cultural values impact on e-service use in Saudi Arabia, and if so how? This paper will firstly, introduce the importance of culture and define the aspects of Saudi culture with focus on our scope: the fear of a lack of Interaction with other Humans. It will then describe the method used and present the qualitative and quantitative findings related to the need for Interactions with other Humans. Much of the written literature about human interaction aims at Information Systems design or design improvement. Yet, this is different to what is being investigated in this study. One of the factors this study will consider is the perceived lack of interaction with other humans or the anxiety people may feel in missing the physical interaction with other people by fully moving business interaction to the virtual world. The review of the literature indicates that the impact of such factor on Information and Communication Technologies (ICT) use has not been studied. This research aims to cover this gap by investigating to what extent the fear of a lack of Interaction with other Humans, as one of Saudi Arabia’s cultural values, impacts on e-service use in Saudi Arabia. The tested hypothesis was found consistent with its predicted outcome: the fear of a lack of Interaction with other Humans is a negative predictor of intention to use e-services in Saudi Arabia. It is evidenced that consideration of the impact of the cultural values will mainly contribute to the enhancement of ICTs implementation and use.