An improved LB method for predicting dynamic characteristics of Vertical Axis Wind Turbine airfoils

One of the important challenges for Vertical Axis Wind Turbine (VAWT) is to fully understand its dynamic characteristics in different operating conditions. Meanwhile, it is necessary to seek a fast and accurate method to evaluate the dynamic characteristic of VAWT. In this study, we improve the LB model by considering the operating principle of VAWT to study the dynamic characteristics of the dedicated and commonly used VAWT airfoils in different operating conditions. The results show that the improved LB model is suitable for simulating the dynamic characteristic of VAWT with a thick airfoil. Although the asymmetric airfoil shows the higher lift coefficient, their dynamic characteristic appears huge fluctuation as the increases of tip speed ratio. Moreover, at a low tip speed ratio, the advantages of the asymmetric airfoil are not obvious. While the dynamic characteristic of the symmetric airfoil is relatively stable with the variation of tip speed ratio.

Numerical Modelling of Underground Water Pipelines exposed to Seismic Loading

The essential factor that must get the interest by the engineers during the primary design stage of underground pipes is understanding mechanism of damage during earthquakes. The attention during design period increased due to the increment of seismic catastrophes throughout the few past decades. Therefore, finite element procedure was used for studying the seismic performance of buried pipes. PLAXIS-2D program was using for simulating the seismic performance of buried pipes using earthquake motion of single frequency. The response of both seismic vertical displacement, and acceleration of the buried pipe were simulated. The experiments of shaking table for two models of buried pipe in dry case that surrounded with sand and gravel were compared with numerical simulation results. According to the obtained results, the amplification of seismic wave raised considerably from the buried pipe base to the pipe crown, the biggest amplification occurred in the highest point of the pipe model. It can be noticed that Plaxis-2D software provides an accurate method for the prediction of seismic behaviour of buried pipe due to the obvious compatibility between the results of experiments and numerical simulation.

Simplified Synthesis and Stability Assessment of Aflatoxin B1-Lysine and Aflatoxin G1-Lysine

Aflatoxins B1 (AFB1) and G1 (AFG1) are carcinogenic mycotoxins that contaminate crops such as maize and groundnuts worldwide. The broadly accepted method to assess chronic human aflatoxin exposure is by quantifying the amount of aflatoxin adducted to human serum albumin. This has been reported using ELISA, HPLC, or LC-MS/MS to measure the amount of AFB1-lysine released after proteolysis of serum albumin. LC-MS/MS is the most accurate method but requires both isotopically labelled and unlabelled AFB1-lysine standards, which are not commercially available. In this work, we report a simplified synthetic route to produce unlabelled, deuterated and 13C6 15N2 labelled aflatoxin B1-lysine and for the first-time aflatoxin G1-lysine. Additionally, we report on the stability of these compounds during storage. This simplified synthetic approach will make the production of these important standards more feasible for laboratories performing aflatoxin exposure studies.

Franz Karl Naegele (1778–1851)

The date of the expected birth is important not just for future parents but rather for obstetricians and gynecologists. Midwives and doctors of all generations know and apply the Naegele rule, based on the dates of menstruation for determining duration of pregnancy. Despite the advent of ultrasound diagnostics that provides a more accurate method to calculate an expected date of birth, up until now the Naegele rule remains relevant.

Meningitis

The term aseptic meningitis encompasses all types of inflammations of the brain meninges other than that caused by pus producing organisms. It is usually a mild illness. Etiology of aseptic meningitis is very wide and includes many infections - both viral and non viral, drugs, malignancy and systemic illness. The most common cause is viral infection and enteroviruses - Coxsackie and ECHO viruses account for more than half of all cases. Clinical manifestations include headache, fever, malaise, photophobia and meningeal signs. Convulsions, neurological deficits and severe obtundation are rare except with certain non viral infectious meningitis. Diagnostic work up includes blood and cerebrospinal fluid (CSF) examination and serology for infectious meningitis. The polymerase chain reaction is a rapid and accurate method for detection of microbial DNA in CSF. Treatment is mainly supportive, except for the nonviral infectious etiology.

A Robust Miniaturized Gas Sensor for H2 and CO2 Detection Based on the 3ω Method

Gas concentration monitoring is essential in industrial or life science areas in order to address safety-relevant or process-related questions. Many of the sensors used in this context are based on the principle of thermal conductivity. The 3ω-method is a very accurate method to determine the thermal properties of materials. It has its origin in the thermal characterization of thin solid films. To date, there have been very few scientific investigations using this method to determine the thermal properties of gases and to apply it to gas measurement technology. In this article, we use two exemplary gases (H2 and CO2) for a systematical investigation of this method in the context of gas analysis. To perform our experiments, we use a robust, reliable sensing element that is already well established in vacuum measurement technology. This helix-shaped thin wire of tungsten exhibits high robustness against chemical and mechanical influences. Our setup features a compact measurement environment, where sensor operation and data acquisition are integrated into a single device. The experimental results show a good agreement with a simplified analytical model and FEM simulations. The sensor exhibits a lower detection limit of 0.62% in the case of CO2, and only 0.062% in case the of H2 at an excitation frequency of 1Hz. This is one of the lowest values reported in literature for thermal conductivity H2 sensors.

A high accurate method for solving an inverse problem of the Laplace equation in detection of a Robin coefficient

This study This work deals with an inverse problem for the harmonic equation to recover a Robin coefficient on a non-accessible part of a circle from Cauchy data measured on an accessible part of that circle. By assuming that the available data has a Fourier expansion, we adopt the Modified Collocation Trefftz Method (MCTM) to solve this problem. We use the truncation regularization method in combination with the collocation technique to approximate the solution, and the conjugate gradient method to obtain the coefficients, thus completing the missing Cauchy data. We recommend the least squares method to achieve a better stability. Finally, we illustrate the feasibility of this method with numerical examples.

Accuracy of abdominal circumference for diagnosing overweight in six-to-seven-years-old children

Objective: To estimate the accuracy of abdominal circumference measurement as a method of diagnosing overweight in six-to-seven-years-old children. Methods: A cross-sectional study involving 1026 six-to-seven-years-old schoolchildren in southern Brazil was carried out. Children’s weight and height were collected at schools. Body mass index were calculated and categorized in z-score in eutrophy, overweight and obesity. Abdominal circumference was measured in centimeters with a tape with children in standing position at midpoint between the lower ribs margin and the iliac crest. Correlation between abdominal circumference and body mass index was performed through Pearson's correlation coefficient. Sensitivity, specificity, positive and negative predictive values of abdominal circumference were estimated. The Receiver Operating Characteristic Curve was used to measure the accuracy. Results: A positive linear correlation value of 0.582 and a determination coefficient 0.39 were observed. The accuracy value of 0.859 was observed. Sensitivity, specificity, positive and negative predictive values varied according to each value in centimeters of abdominal circumference. Conclusion: Abdominal circumference measure showed to be an accurate method for detecting overweight and obesity in six-to-seven-years-old children.