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1.
Yasmine El-Ashi Taha Landolsi Rached Dhaouadi 《Journal of The Franklin Institute》2011,348(7):1435-1455
In this paper, we study the accuracy of an optical vibration sensing system using Gaussian beam analysis. The proposed optical system uses a He-Ne laser source whose Gaussian beam impinges on a quad-cell photodetector array. The normalized optical power for each cell is obtained through numerical simulation based on the well-known Gaussian beam optics formulation, as the beam scans the plane of the photodetectors due to vibration. The system detection principle lies upon finding a relationship between the power distribution of the quad-cell and the position of the beam centroid, which allows us to identify the characteristics of the vibration applied, such as direction, frequency and strength. The aspects of practical implementation and experimental limitations on the power distribution accuracy are discussed and the discrepancies with the theoretical results are presented. 相似文献
2.
Mohammad Taha Jalali Abdolhosain Mosavi Honomaror Abdolkarim Rekabi Mahmod Latifi 《Indian journal of clinical biochemistry : IJCB》2013,28(3):277-282
Cardiovascular diseases (CVD) are recognized as major mortality causes and imposes tremendously heavy socio-economic burden worldwide. A vast variety of risk factors have been introduced in the literature known to enhance the incidence of CVD, such as hyperlipidemia. Therefore in order to make an accurate clinical decision it is essential to have appropriate reference ranges for lipids and lipoprotein particles in a particular population. Healthy female (n = 601) and male (n = 617) cases were randomly selected according to certain exclusion criteria from individuals visiting the major University hospital clinics situated in different part of Ahvaz city, Iran, from June 2010 to December 2010. Fasting blood samples (10 ml) were collected and analyzed for total cholesterol, total triglyceride and HDL-C employing enzymatic assays of CHOD-PAP, GPO-PAP and homogenous methods respectively. The samples were obtained such to include the ethnic populations of Persian, Arab. Lore leaving in this city. The data were analyzed statistically by SPSS-18 software. The obtained results were analyzed then age ethnic-wise and reference ranges (mean ± 1SD) were calculated. Remarkable differences between the obtained results for our population with other nations were seen. Also ethnic difference for HDL-C among our cases was noted. The observed significant differences among different nations and ethnicities emphasizes the need for nation-specific, local reference ranges for lipids and lipoproteins particles, to be established. 相似文献
3.
Mahmoud Mekadem Taha Chettibi Samir Hanchi Laurent Keirsbulck Larbi Labraga 《浙江大学学报(A卷英文版)》2012,13(2):105-120
The propulsive efficiency of a plunging NACA0012 airfoil is maximized by means of a simple numerical optimization method based
on the response surface methodology (RSM). The control parameters are the amplitude and the reduced frequency of the harmonic
sinusoidal motion. The 2D unsteady laminar flow around the plunging airfoil is computed by solving the Navier-Stokes equations
for three Reynolds number values (Re = 3.3×103, 1.1×104, and 2.2×104). The Nelder-Mead algorithm is used to find the best control parameters leading to the optimal propulsive efficiency over
the constructed response surfaces. It is found that, for a given efficiency level and regardless of the considered Re value, it is possible either to obtain high thrust by selecting a high oscillation frequency or to reduce the input power
by adopting a low plunging amplitude. 相似文献
4.
The contribution of linguistic and cognitive variables to reading processes might vary depending on the particularities of the languages studied. This view is thought to be particularly true for Arabic which is a diglossic language and has particular orthographic and morpho-syntactic systems. This cross-sectional study examined the contribution of phonological, orthographic, morphological, semantic, syntactic, visual perception, rapid automatic naming and phonological working memory abilities to decoding and fluency (the two components of reading). The results, obtained from 1305 native Arabic-speaking children in first–sixth grade, were analyzed using path models. The analysis revealed that memory and orthographic knowledge contributed to both components of reading, while phonological awareness contributed mainly to decoding and rapid automatic naming contributed to fluency. The contribution of morphology to the two components, which appeared already in the first grade, was weak and inconsistent. Finally, the results showed that visual perception, semantics, and syntax predicted neither decoding nor fluency. The data presented here suggest that reading development in Arabic differs from other languages, a finding that might explain certain difficulties in reading acquisition in Arabic. The results are discussed in the light of previous findings in the literature and the specific features of Arabic. 相似文献
5.
ABSTRACTMany older adults who lose their jobs face challenges in finding new employment due to fundamental limitations in their technology skills. While training could give them the skills they need, older workers often have less access to training programs than younger workers. This study examined the feasibility of using an e-learning training program developed for older job-seeking adults lacking the requisite technology skills to find employment. Implementation of the training program was based on a partnership established between university researchers and a community organization. Thirty-five participants aged 50–71 years provided data regarding their previous work histories and problems that they encountered while seeking employment. They completed 12 hours of training in Microsoft Excel and were given multiple-part problems to assess what they had learned. They also provided evaluations of the program. Participants who enrolled in the training had limited computer skills; after a relatively short amount of training, many were able to perform Excel functions such as entering data and using formulas. Most participants indicated that the training they received was very beneficial, and that they had a basic understanding of Excel. Overall, this project demonstrated that academic-community partnerships can provide an effective strategy for delivering training to older adults. 相似文献
6.
This study was an investigation of reading and spelling errors of dyslexic Arabic readers (n=20) compared with two groups of normal readers: a young readers group, matched with the dyslexics by reading level (n=20) and an age-matched group (n=20). They were tested on reading and spelling of texts, isolated words and pseudowords. Two research questions were the focus of this study: What are the reading and spelling profile errors of dyslexic native Arabic speakers? What is the effect of the Arabic orthography on these types of errors? The results of the reading error analysis revealed a clear contribution of the uniqueness of the Arabic orthography to the types of errors made by the three different groups. In addition, the error profiles of the dyslexic readers were similar to the error profiles made by the younger reading-level-matched group in percentages and in quality. The most prominent types of errors were morphological and semiphonetic, which highlighted the contribution of the Arabic orthography to these types of errors. Consistently, the profile of the spelling errors was similar in percentages and quality among the dyslexics and the reading-level-matched group but different from the age-matched group on the spelling measures. The analysis of the spelling errors revealed that the dominant type of error was mostly phonetic due to the limited orthographic lexicon. In addition, the Arabic orthography also contributed to these types of errors because many spelling mistakes were made due to poor knowledge of the spelling rules. The results of the reading and spelling errors are discussed from a reading development point of view. Further, two models are suggested, one for reading and one for spelling, to illustrate the cognitive processes that underlie the reading and spelling mistakes in this type of orthography. 相似文献
7.
Zahari Ishak Suet Fin Low Poh Li Lau 《Journal of Science Education and Technology》2012,21(4):487-493
Parenting styles have always been a crucial factor in influencing all aspects of a person??s development. The purpose of this study is to test the structural equation model of academic achievement among the students using parenting styles as a moderator. The sample comprised 493 students from eight schools. Parenting styles are determined using the Parental Authority Questionnaire (Buri in J Pers Assess 57:110?C119, 1991). Academic achievement is measured based on the students?? performance in the Lower Secondary Assessment. Data were analyzed using structural equation modelling. Results demonstrated that model of authoritative and model of authoritarian fit the data of this study well. Both authoritative and authoritarian parenting styles are the most common practice of the parents. Parenting styles have been found to be a moderator of this study. The results indicated that parenting styles moderated the effect of academic self-concept on academic achievement. The impact of academic self-concept on academic achievement is found to be greater for the authoritative than the authoritarian parenting style. 相似文献
8.
Zahari TAHA Hani-kumiati LELANA Hideki AOYAMA Raja Ariffin RAJA GHAZILLA Julirose GONZALES Novita SAKUNDARINI Sugoro B. SUTONO 《浙江大学学报(A卷英文版)》2010,(12):966-971
Surface roughness is an important parameter for ensuring that the dimension of geometry is within the permitted tolerance.The ideal surface roughness is determined by the feed rate and the geometry of the tool.However,several uncontrollable factors including work material factors,tool angle,and machine tool vibration,may also influence surface roughness.The objective of this study was to compare the measured surface roughness (from experiment) to the theoretical surface roughness (from theoretical calculation) and to investigate the surface roughness resulting from two types of insert,‘C’ type and ‘T’ type.The experiment was focused on the turning process,using a lathe machine Colchester 6000.The feed rate was varied within the recommended feed rate range.We found that there were large deviations between the measured and theoretical surface roughness at a low feed rate (0.05 mm/r) from the application of both inserts.A work material factor of AISI D2 steel that affects the chip character is presumably responsible for this phenomenon.Interestingly,at a high feed rate (0.4 mm/r),the ‘C’ type insert resulted in 40% lower roughness compared to the ‘T’ type due to the difference in insert geometry.This study shows that the geometry of an insert may result in a different surface quality at a particular level of feed rate. 相似文献
9.
Designing reliable flight control for an autonomous helicopter requires a high performance dynamics model.In this paper,a nonlinear autoregressive with exogenous inputs （NLARX） model is selected as the mathematical structure for identifying and controlling the flight of a small-scale helicopter.A neural network learning algorithm is combined with the NLARX model to identify the dynamic component of the rotorcraft unmanned aerial vehicle （RUAV）.This identification process is based on the well-known gradient descent learning algorithm.As a case study,the multiple-input multiple-output （MIMO） model predictive control （MPC） is applied to control the pitch motion of the helicopter.Results of the neural network output model are closely match with the real flight data.The MPC also shows good performance under various conditions. 相似文献
10.
Health literacy has emerged as an important factor related to health in older persons. The reason for the link between health literacy and health outcomes is not clear. Possible explanations include common relations among income, education, access to health care, health-promotion behaviors, frequency of reading, and perceptual impairments. In this study we investigate the relation of health literacy to self-reported health status and explore the impact of these explanatory variables on this relation in persons aged 40 years and older who participated in the 2003 U.S. National Assessment of Adult Literacy (NAAL). Using regression models, we evaluated the impact of potential explanatory variables on the relation of health literacy to self-reported health status. Regression models confirmed previously-observed relations of health literacy, age, income, and education to health. The inclusion of income and education significantly decreased the relation of health literacy to health. While other variables, such as health maintenance and preventive health behaviors, were significantly related to health, they did not change the relation of health literacy to health. Even after taking multiple explanatory variables into account, the relation between health literacy and health status remained significant, suggesting that they alone do not completely account for the observed relation. Some other factor or combination of factors may account for the relation of health literacy to health. 相似文献