50 research outputs found

    Investigate of the influence for multiple resistance welding currents in austerities nickel-chromium alloys on welded joints mechanical characteristics

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    We have studied the shear strength, with regards to 302 “austenitic stainless steel spot welds”. It is undeniable that the current for a welding within resistance spot welding development (RSW) shows a very important character. Nevertheless, these effects of this item are popular so it has been considered widely all through literature works. Our aim in this work is to show the effect of heat treatment on different joints welded at multiple currents. The experimental results demonstrate about a tensile shear strength that could be increased together along with the increasing in refer to current. Annealing treatment increases escorted by tensile shear strength as a size of grain reforms, in addition the remaining stresses removed. Refinement of grain serves to be an operative practice for a strength improvement. With that, the tensile; shear strength could be increased through having the annealed temperature of treatment reached; 750 C°. Regardless, at 850 C°, the tensile shear strength decreases

    A laboratory study of the effect of fiberglass additive on the behavioural properties of rap asphalt mixtures

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    The increase in the amount of reclaimed asphalt pavement (RAP) and environmental concerns for bitumen production have contributed to the use of RAP in road construction and maintenance. The use of higher than 15% of RAP adversely affects the physical and rheological properties of the asphalt binder and the mechanical properties of mixtures. Therefore, the use of bitumen and asphalt mixture improver were necessary to reduce the negative effects generated with the use of RAP. This paper aims to study the effect of fiberglass (FG) (0.5%, 1.0%, 1.5%, and 2%) on the mechanical properties of asphalt concrete containing 25%, 50% RAP and 9% waste engine oil. The performance of RAP asphalt mixtures incorporated with FG was evaluated using the Marshall stability test, moisture susceptibility test, and immersion wheel rutting test. The results indicated that the use of FG and RAP materials to rejuvenated asphalt mixtures resulted in an increase in the values of Marshall stability and rutting resistance. Moreover, the study revealed that increasing the content of RAP material and FG results in increased resistance of asphalt to moisture damage. This paper concluded that using 0.15% of FG and 50% RAP materials gives the best results

    Composite patch reinforcement of a cracked simply-supported beam traversed by moving mass

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    In this study dynamic analysis of a metallic beam under travelling mass was investigated. A beam with an edge crack was considered to be reinforced using composite patch. Euler-Bernoulli beam theory was applied to simulate the time-history behavior of the beam under dynamic loading. Crack in the beam was modeled using a rotational spring. Dimension of the composite patch, crack length, stress intensity factor at crack tip and beam deflection are some parameters which were studied in details. Results were validated against those which were found through Finite Element Method

    Scholarly publishing depends on peer reviewers

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    The peer-review crisis is posing a risk to the scholarly peer-reviewed journal system. Journals have to ask many potential peer reviewers to obtain a minimum acceptable number of peers accepting reviewing a manuscript. Several solutions have been suggested to overcome this shortage. From reimbursing for the job, to eliminating pre- publication reviews, one cannot predict which is more dangerous for the future of scholarly publishing. And, why not acknowledging their contribution to the final version of the article published? PubMed created two categories of contributors: authors [AU] and collaborators [IR]. Why not a third category for the peer-reviewer

    Parameters for the mathematical modelling of Clostridium difficile acquisition and transmission: a systematic review

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    INTRODUCTION: Mathematical modelling of Clostridium difficile infection dynamics could contribute to the optimisation of strategies for its prevention and control. The objective of this systematic review was to summarise the available literature specifically identifying the quantitative parameters required for a compartmental mathematical model of Clostridium difficile transmission. METHODS: Six electronic healthcare databases were searched and all screening, data extraction and study quality assessments were undertaken in duplicate. Results were synthesised using a narrative approach. RESULTS: Fifty-four studies met the inclusion criteria. Reproduction numbers for hospital based epidemics were described in two studies with a range from 0.55 to 7. Two studies provided consistent data on incubation periods. For 62% of cases, symptoms occurred in less than 4 weeks (3-28 days) after infection. Evidence on contact patterns was identified in four studies but with limited data reported for populating a mathematical model. Two studies, including one without clinically apparent donor-recipient pairs, provided information on serial intervals for household or ward contacts, showing transmission intervals of <1 week in ward based contacts compared to up to 2 months for household contacts. Eight studies reported recovery rates of between 75%-100% for patients who had been treated with either metronidazole or vancomycin. Forty-nine studies gave recurrence rates of between 3% and 49% but were limited by varying definitions of recurrence. No study was found which specifically reported force of infection or net reproduction numbers. CONCLUSIONS: There is currently scant literature overtly citing estimates of the parameters required to inform the quantitative modelling of Clostridium difficile transmission. Further high quality studies to investigate transmission parameters are required, including through review of published epidemiological studies where these quantitative estimates may not have been explicitly estimated, but that nonetheless contain the relevant data to allow their calculation

    Scholarly publishing depends on peer reviewers

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    The peer-review crisis is posing a risk to the scholarly peer-reviewed journal system. Journals have to ask many potential peer reviewers to obtain a minimum acceptable number of peers accepting reviewing a manuscript. Several solutions have been suggested to overcome this shortage. From reimbursing for the job, to eliminating pre-publication reviews, one cannot predict which is more dangerous for the future of scholarly publishing. And, why not acknowledging their contribution to the final version of the article published? PubMed created two categories of contributors: authors [AU] and collaborators [IR]. Why not a third category for the peer-reviewer?Scopu

    Genetic diversity of aromatic rice germplasm revealed by SSR markers

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    Aromatic rice cultivars constitute a small but special group of rice and are considered the best in terms of quality and aroma. Aroma is one of the most significant quality traits of rice, and variety with aroma has a higher price in the market. This research was carried out to study the genetic diversity among the 50 aromatic rice accessions from three regions (Peninsular Malaysia, Sabah, and Sarawak) with 3 released varieties as a control using the 32 simple sequence repeat (SSR) markers. The objectives of this research were to quantify the genetic divergence of aromatic rice accessions using SSR markers and to identify the potential accessions for introgression into the existing rice breeding program. Genetic diversity index among the three populations such as Shannon information index () ranged from 0.25 in control to 0.98 in Sabah population. The mean numbers of effective alleles and Shannon’s information index were 0.36 and 64.90%, respectively. Similarly, the allelic diversity was very high with mean expected heterozygosity () of 0.60 and mean Nei’s gene diversity index of 0.36. The dendrogram based on UPGMA and Nei’s genetic distance classified the 53 rice accessions into 10 clusters. Analysis of molecular variance (AMOVA) revealed that 89% of the total variation observed in this germplasm came from within the populations, while 11% of the variation emanated among the populations. These results reflect the high genetic differentiation existing in this aromatic rice germplasm. Using all these criteria and indices, seven accessions (Acc9993, Acc6288, Acc6893, Acc7580, Acc6009, Acc9956, and Acc11816) from three populations have been identified and selected for further evaluation before introgression into the existing breeding program and for future aromatic rice varietal development

    Measuring the health literacy level of Arabic speaking population in Saudi Arabia using translated health literacy instruments

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    Background: Health literacy is an essential predictor of health status, disease control and adherence to medications. Objectives: The study goals were to assess the health literacy level of the general population in Saudi Arabia using translated Gulf Arabic version of the short-version of the Test of Functional Health Literacy in Adults (S-TOFHLA) and Single Item Literacy Screener (SILS) tests and to measure the relationship between health literacy and education level. Methods: The study was a cross-sectional with a convenience sample of 123 participants from the general population in Riyadh. Data were collected using the modified (Gulf) Arabic versions of both S-TOFHLA and SILS. Fisher’s Exact test was used to measure the difference of the health literacy scores according to the education degrees and Cronbach’s alpha was used to measure the internal consistency of the S-TOFHLA items. Results: More than half (55.4%) of the participants were male, 50.4% had a middle school or less education level, and we found that 84.4% had adequate health literacy as measured by the S-TOFHLA, compared to 49.6% as measured by SILS. The Fisher’s Exact test showed a significant difference (P<.05) in the S-TOFHLA and SILS scores according to education categories. Conclusions: The level of education has a significant positive association with S-TOFHLA and SILS results. The Gulf Arabic version of S-TOFHLA is a reliable test with a good internal consistency and a significant positive correlation between the two parts of S-TOFHLA. We recommend the use of S-TOFHLA or SILS at the first patient visit.

    Damage classification in carbon fibre composites using acoustic emission: A comparison of three techniques

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    Classifying the type of damage occurring within a structure using a structural health monitoring system can allow the end user to assess what kind of repairs, if any, that a component requires. This paper investigates the use of acoustic emission (AE) to locate and classify the type of damage occurring in a composite, carbon fibre panel during buckling. The damage was first located using a bespoke location algorithm developed at Cardiff University, called delta-T mapping. Signals identified as coming from the regions of damage were then analysed using three AE classification techniques; artificial neural network (ANN) analysis, unsupervised waveform clustering (UWC) and corrected measured amplitude ratio (MAR). A comparison of results yielded by these techniques shows a strong agreement regarding the nature of the damage present in the panel, with the signals assigned to two different damage mechanisms, believed to be delamination and matrix cracking. Ultrasonic C-scan images and a digital image correlation (DIC) analysis of the buckled panel were used as validation. MAR's ability to reveal the orientation of recorded signals greatly assisted the identification of the delamination region, however, ANN and UWC have the ability to group signals into several different classes, which would prove useful in instances where several damage mechanisms were generated. Combining each technique's individual merits in a multi-technique analysis dramatically improved the reliability of the AE investigation and it is thought that this cross-correlation between techniques will also be the key to developing a reliable SHM system
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