Mechanical behavior of GFRP laminated composite pipe subjected to uniform radial patch load

Cylindrical vessels are widely used for storage and transportation of fluids. Using composites shells can improve the corrosion resistance of the product and reduce weight therefore investigation of the mechanical behavior is important. For this purpose cylinders with 6, 12 and18-ply of GFRP , with symmetric ply sequence of [90/0/90]s, [90/0/90/0/90/0]s and, [90/0/90/0/90/0/90 /0/90]s with layer thickness 1.3 mm and mean radius 250 mm, are considered under uniform radial patch load. The analysis was based on the shell theory and classical mechanics of laminated composites. A code was written using MATLAB software to compute stress and deflection of the cylinder shell. In numerical simulation, each unidirectional composite ply is treated as an equivalent elastic and orthotropic panel. Analysis is focused on the area of cylinder where the patch load is applied. The results show that the analytical prediction compares well with numerical responses of previous literature. The procedure can be used to predict maximum stress and displacement in a multi-layer shell for various types of similar loading

Mechanical behavior of composite plate under combined impact and internal pressure

This research presents results obtained from numerical analysis of a circular composite plate under impact of drop hammer and internal pressure load simultaneously. Influence of reinforced orientationangles of the multi-layer composite plate with fixed boundary conditions on displacements and axial stresses along the radius direction was studied. Employing ABAQUS software results for reinforcedorientation angles of [0/90/0]s, [0/45/60]s, [0/45/90]s, [0/30/60]s, [0/30/75]s, [0/15/30/60/75/90],[0/45/90/90/-45/0] are compared. Finding indicated that the reinforcedorientation angles have considerable effect on the axial stresses changing from compressive to tensile stresses. [0/45/90/90/-45/0]s showed the minimum displacements and axial stresses

Mechanical response of laminated composite cylindrical shell subjected to radial patch loading

Due to significant amount of applications in industries, composite materials and structures are subjected to many different types of loading. One of the most common types of these loading is radial patch loading. Due to the complexity, calculation of radial shell deflection is the main character of the cylinder behavior when subjected to patch loading. The aim of this study is to investigate the mechanical behavior of composite cylindrical shell subjected to radial patch loading. The radial deflection of the laminated shell is investigated in detail where analytical and finite element methods (FEM) are used. The results through both approaches are compared to validate the accuracy of the analytical method. This is followed by a parametric study to determine the effect of some operation parameters on radial displacement. The results show close agreement between the analytical and numerical methods

Color Doppler ultrasonography diagnostic value in detection of malignant nodules in cysts with pathologically proven thyroid malignancy: a systematic review and meta-analysis

Aims: Today, the color Doppler ultrasonography is used to further evaluate suspected malignant tumors. This study investigates the malignant thyroid nodules using color Doppler. Methods: After extracting true positive, false positive, false negative, and true negative among included studies, a quality was evaluated by the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio (with 95% confidence interval) were found using a random effect model. Summary receiver operating characteristic curves (SROC) were used to assess relationship between sensitivity and specificity. The area under the curve of the SROC was calculated to estimate the performance of color Doppler ultrasound to distinguish malignant thyroid nodules. Our registration code in PROSPERO is CRD42018111198. Results: Of 1125 articles, 288 articles were selected for the further investigation. After excluding irrelevant and poor articles, 20 studies were included for the meta-analysis. According to a random effect model, the pooled sensitivity and specificity of color Doppler ultrasound to distinguish malignant thyroid nodules were estimated as 0.74 (95% CI 0.62–0.83; I 2 = 89.94 %) and 0.70 (95% CI 0.56–0.81; I 2 = 97.79 %), respectively. The SROC curve consists of representing the paired results for sensitivity and specificity. According to SROC, AUC = 0.78 (95% CI 0.74–0.81) is between 0.75 and 0.92, so that color Doppler ultrasound has a good accuracy. Conclusion: Color Doppler is a valuable non-invasive method for evaluating thyroid nodules, and it is a high-sensitivity diagnostic tool for assessing thyroid nodules. Resistive index > 0.75 and a pattern III or more in color Doppler predicts malignant with the confidence. Due to its precision, cost-efficiency, easy access, and non-invasive nature, color Doppler should be included in the standard clinical protocol for the decision-making period and the treatment evaluatio

Status of fasciolosis among domestic ruminants in Iran based on abattoir data: a systematic review and meta-analysis

Fasciolosis is considered as an ongoing neglected zoonotic disease in tropical regions of the world, relating to notable financial and public health issues. The current systematic review and meta-analysis was planned to determine the status of fasciolosis among domestic ruminants, including cattle, buffalo, goat, and sheep at the industrial slaughterhouses in Iran, between the years 2000 and 2016. Eight databases, four English and four Persian, were searched. Our findings demonstrated that 2.6 of all inspected livers of slaughtered ruminants were infected with Fasciola spp. during 2000�2016. The mean prevalence of fasciolosis for cattle, buffalo, goat, and sheep was 21, 4.2, 2, and 2.4, respectively. Additionally, most studies were performed on cattle 25 (39.6), sheep 24 (38 ), and goat 12 (19), respectively, and just 2 (3.1) studies were performed on buffalo. The prevalence of animal fasciolosis has significantly decreased among domestic ruminants in Iran except for cattle. In addition, the prevalence of this disease in Northern and Western regions of the country has remained at hypo-endemic level. The results present updated gathered information on the epidemiology of fasciolosis in domestic ruminants in Iran, and will expand the screening strategies to improve health and reduce economic impacts among farm animals

Effect of nano-additives on the strength and durability characteristics of marl

Low bearing capacity soils may pose serious construction concerns such as reduced bearing capacity and excessive hydro-associated volume changes. Proper soil remediation techniques must be planned and implemented before commencing any construction on low bearing capacity soils. Environmentally friendly soil stabilizers are gradually replacing traditional soil stabilizers with high carbon dioxide emissions such as lime and cement. This study investigated the use of an alternative pozzolanic mix of nano-additives (i.e., nano-silica and nano-alumina) and cement to re-duce the usage of cement for achieving competent soil stabilization outcomes. A series of unconfined compressive strength (UCS), direct shear, and durability tests were conducted on marl specimens cured for 1, 7, and 28 days stabilized with nano-additives (0.1~1.5%), 3% cement, and combined 3% cement and nano-additives. The UCS and shear strength of stabilized marl increased with nano-additives up to a threshold nano-additive content of 1% which was further intensified with curing time. Nano-additive treated cemented marl specimens showed long durability under the water, while the cemented marl decomposed early. The microfabric inspection of stabilized marl specimens showed significant growth of calcium silicate hydrate (CSH) products within the micro fabric of nano-silica treated marl with reduced pore-spaces within aggregated particles. The results confirmed that nano-additives can replace cement partially to achieve multi-fold improvement in the strength characteristics of the marl

Pediculosis capitis among school-age students worldwide as an emerging public health concern: a systematic review and meta-analysis of past five decades

Pediculosis by Pediculus humanus capitis is still an important health issue in school-age students worldwide. Although pediculicidal agents effectively kill head lice, the re-infestation rate is still high. This study was conducted to provide a summary of evidence about the prevalence of pediculosis capitis among school-age students worldwide. Different databases including MEDLINE/PubMed, Scopus, and Web of Science were searched for publications related to pediculosis capitis in school-age students from 1977 to 2020. All peer-reviewed original research articles describing pediculosis capitis among school-age students were included. Statistical heterogeneity of the different years among studies was assessed using the standard chi squared and I2 tests. Due to the significant heterogeneity, a random effect model was adopted to estimate the pooled, continent, and gender-specific prevalence of pediculosis. Two hundred and one papers met the inclusion criteria of this review and entered into the meta-analysis including 1,218,351 individuals. Through a random effect model, the prevalence of pediculosis capitis among school students was estimated as 19% (CI 95% = 0.18–0.20%, I2 = 99.89%). The prevalence of pediculosis capitis among boys was 7% (CI 95% = 0.05–0.10) compared to 19% (CI 95% = 0.15–0.24) in girls. The highest prevalence was in Central and South America (33%, CI 95% = 0.22–0.44, I2 = 99.81%) and the lowest was in Europe (5%, CI 95% = 4–6, I2 = 99.28%). Relatively high pediculosis capitis prevalence among school-age students observed in this study emphasizes the need for implementing screening and prophylaxis tailored to the local context

A new analytical method for determination of discharge duration in tunnels subjected to groundwater inrush

Unexpected water inrush to tunnels is one of the most hazardous events, especially in karst terrains that could take place during mechanized shield tunneling mostly due to inappropriate site investigations. When water inrushes to tunnel front, actions like pumping out the water or grouting, for impeding or reducing the inrush and alleviating related damages, are often time-consuming, uneconomical, difficult, or sometimes even impossible. In most cases, it is sometimes necessary to wait for lowering groundwater within the tunnel to have again the possibility to excavate. Therefore, determination of the required time for the groundwater inrush to decrease to a certain level is extremely important for tunneling management plans and plays a significant role in decision-making for project managers. In this study, an assessment of the discharge time after water inrush to tunnel using the new proposed analytical approach is argued. This method is developed based on recession analysis and hydrodynamic of open channels. For this purpose, inrush rate to tunnel front and groundwater level should be measured on at least a daily basis, a feasible and practical action to be carried out on tunnel construction sites. The method is validated with available data from three tunnels with water inrush experiences. The results show that the analytically determined water inrush regime is in good accordance with the observed ones