3,498 research outputs found

    Critical gap analysis of merging sections at Kuala Lumpur middle ring road

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    At merging sections, drivers normally slow down and sometimes need to stop while seeking a suitable gap before merging with the mainstream. Thus, there will always be several observed rejected gaps and an accepted gap which can be used to determine the smallest average gap, so-called critical gap. This study was carried out to determine critical gap values at selected merging sections at the Jalan Tun Razak and the DUKE Expressway uses the Maximum Likelihood method. Data were collected by using videotaping method and the gap acceptance data were extracted for analysis. A gap acceptance event at highway merging sections in this study was redefined due to unavailability of stopping vehicles at the ramp junction. Therefore, the gap data were estimated starting from a ramp’s vehicle passing the end of gore marking to where it merges with the mainstream. The analysis of the critical gap takes into consideration accepted gaps greater than 5 seconds to avoid forced entry due to lead impedance of successive vehicles on mainstream. The critical gap values obtained in this study, according to vehicle classification were ranged between 4.5 to 5.0 seconds, which are slightly smaller if compared to critical gap values for particularly left turn from minor movement at priority junction of the Arahan Teknik (Jalan) 11/87 and the United States Highway Capacity Manual 2000. The findings shall help to study driving behavior of local drivers, especially at priority control facilities such as merging sections

    Prediction of Water Activity Coefficient in TEG-Water System Using Diffusion Neural Network (DNN)

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    Accurate determination of activity coefficients of water in a binary triethylene glycol (TEG)-water system, is of prime concern in designing the natural gas dehydration process. In this work, a hybrid model (a combination of information diffusion theory and neural network) and a so-called diffusion neural network (DNN) have been developed for the prediction of activity coefficients of a binary TEG-water system. Owing to the insufficient experimental data available in the literature for binary mixtures, and in particular for infinite dilution, we have employed the information diffusion technique as a tool in extrapolating data points from the original data. By means of this technique, a new dataset has been trained and optimized for the DNN model with more nodes in the input and the output layers. The result of this study reveals that DNN model is superior to the conventional neural nets in predicting the activity coefficient of water in the range of temperature (293–387.6 K) and mole fractions with mean absolute error of 0.31 % (MAE = 0.31 %), and high correlation coefficient of 0.999 (r = 0.999). Furthermore, the results of this work using DNN have also been compared with Parrish’s correlation. The findings of this work demonstrate that the DNN model exhibits better results over Parrish’s correlation in predicting the activity coefficients of water in a binary triethylene glycol-water system with a mean absolute error of 5.03 percent (MAE = 5.03 %)

    Assessment of cytological and morphological variation among Iranian native Iris species

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    In order to study the morphological and cytological variation among Iranian native Irises, first, morphological traits were analyzed in order to clarify taxonomic relationships among taxa and validity of diagnostic characters. Floral and vegetative characters were measured in 54 plant samples belonging to five species during peak of the flowering season in 2008. Analysis of variance showed significant differences. Result of analysis shows that the most variation coefficient belongs to leaf width. Correlation of coefficients defined between the date of the first blooming of the flowers and the date of the least blooming of the flowers, flowers surface and diameter had the positive and significant correlation. Factor analysis showed that only three factors define almost near to 92% variance among characters. Secondly, in cytological variation each species showed different karyotypic formula such as 2n = 2sm+ 14st+4t for Iris meda, 2n = 8m + 16sm + 20st with one pair of terminal satellite chromosomes for Iris caspica, 2n = 26m + 18sm for Iris spuria, 2n= 14m + 12sm + 8st with one pair of terminal satellite chromosomes for Iris pseudacorous and 2n= 8m + 20sm + 20st for Iris germanica. This is the first karyotypic report in I. caspica, I. spuria and I. meda species in Iran. The results seemed to provide enough genetic evidence to identify each species and useful data to clarify the interspecific relationships among Iranian native Iris species.Key words: Iris, karyotype, Iranian native, chromosome analysis, genome

    Evaluation of different methods of determining the angle of attack on wind turbine blades under yawed inflow conditions

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    As part of the AVATAR and Mexnext projects, this study compares several methods used to derive lifting line variables from CFD simulations of the MEXICO rotor in yawed inflow. The results from six partners within the AVATAR/Mexnext consortium using five different methods of extraction were compared. Overall comparison of the induced velocities at the mid and tip parts of blade shows fairly good agreement between the tested methods, where the derived angle of attack differs within 1°, within the linear range this accounts to ˂ 10% uncertainty on the aerodynamic forces. The presented comparison shows inadequate agreement between the methods for application towards the root

    Efficacy and acceptability of a pilot dietary intervention focusing on self-compassion, goal-setting and self-monitoring.

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    OBJECTIVE:Overweight and obesity are universal health challenges. Recent evidence emphasises the potential benefits of addressing psychological factors associated with obesity in dietary programmes. This pilot study investigated the efficacy and acceptability of a combined online and face-to-face dietary intervention that used self-compassion, goal-setting and self-monitoring to improve dietary behaviour, as well as psychological factors associated with dietary behaviour. DESIGN:Embedded mixed methods including a 4-week before-after trial and a one-on-one interview. Quantitative outcomes of the study were the levels of self-compassion; eating pathology; depression, anxiety and stress; and dietary intake. Qualitative outcomes were participants' perceptions about the acceptability of the intervention. SETTING:UNSW Kensington campus. PARTICIPANTS:Fourteen participants with overweight and obesity aged between 18 and 55 years old. RESULTS:Results showed that the intervention significantly improved self-compassion and some aspects of dietary intake (e.g. decrease in energy intake) at Week Four compared with Week Zero. Some aspects of eating pathology also significantly decreased (e.g. Eating Concern). However, changes in self-compassion over the 4 weeks did not significantly predict Week Four study outcomes, except for level of stress. Most participants found self-compassion, goal-setting and self-monitoring to be essential for dietary behaviour change. However, participants also indicated that an online programme needed to be efficient, simple and interactive. CONCLUSIONS:In conclusion, the current study provides preliminary but promising findings of an effective and acceptable combined online and face-to-face intervention that used self-compassion, goal-setting and self-monitoring to improve dietary habits. However, the results need to be examined in future long-term randomised controlled trials

    Final results from the EU project AVATAR: aerodynamic modelling of 10 MW wind turbines

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    This paper presents final results from the EU project AVATAR in which aerodynamic models are improved and validated for wind turbines on a scale of 10 MW and more. Special attention is paid to the improvement of low fidelity engineering (BEM based) models with higher fidelity (CFD) models but also with intermediate fidelity free vortex wake (FVW) models. The latter methods were found to be a good basis for improvement of induction modelling in engineering methods amongst others for the prediction of yawed cases, which in AVATAR was found to be one of the most challenging subjects to model. FVW methods also helped to improve the prediction of tip losses. Aero-elastic calculations with BEM based and FVW based models showed that fatigue loads for normal production cases were over predicted with approximately 15% or even more. It should then be realised that the outcome of BEM based models does not only depend on the choice of engineering add-ons (as is often assumed) but it is also heavily dependent on the way the induced velocities are solved. To this end an annulus and element approach are discussed which are assessed with the aid of FVW methods. For the prediction of fatigue loads the so-called element approach is recommended but the derived yaw models rely on an annulus approach which pleads for a generalised solution method for the induced velocities

    Effect of substrate grain size on structural and corrosion properties of electrodeposited nickel layer protected with self-assembled film of stearic acid

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    In the present study, the impact of copper substrate grain size on the structure of the succeeding electrodeposited nickel film and its consequent corrosion resistance in 3.5% NaCl medium were evaluated before and after functionalization with stearic acid. Nickel layers were electrodeposited on two different copper sheets with average grain size of 12 and 25 \u3bcm, followed by deposition of stearic acid film through self-assembly. X-ray diffraction analysis of the electrodeposited nickel films revealed that the deposition of nickel film on the Cu substrate with small (12 \u3bcm) and large (25 \u3bcm) grains is predominantly governed by growth in the (220) and (111) planes, respectively. Both electrodeposited films initially exhibited a hydrophilic nature, with water-contact angles of 56\ub0 and <10\ub0, respectively. After functionalization with stearic acid, superhydrophobic films with contact angles of ~150\ub0 were obtained on both samples. In a 3.5% NaCl medium, the corrosion resistance of the nickel layer electrodeposited on the copper substrate with 25 \u3bcm grains was three times greater than that deposited on the copper substrate with 12 \u3bcm grains. After functionalization, the corrosion resistance of both films was greatly improved in both short and long immersion times in 3.5% NaCl medium

    Localization of elastic waves in heterogeneous media with off-diagonal disorder and long-range correlations

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    Using the Martin-Siggia-Rose method, we study propagation of acoustic waves in strongly heterogeneous media which are characterized by a broad distribution of the elastic constants. Gaussian-white distributed elastic constants, as well as those with long-range correlations with non-decaying power-law correlation functions, are considered. The study is motivated in part by a recent discovery that the elastic moduli of rock at large length scales may be characterized by long-range power-law correlation functions. Depending on the disorder, the renormalization group (RG) flows exhibit a transition to localized regime in {\it any} dimension. We have numerically checked the RG results using the transfer-matrix method and direct numerical simulations for one- and two-dimensional systems, respectively.Comment: 5 pages, 4 figures, to appear in Phys. Rev. Let
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