Comparison of optimizer-based and flow solver-based trimming in the context of high-fidelity aerodynamic optimization

This report compares two approaches for achieving a trimmed state of an aircraft configuration during an aerodynamic optimization. In the optimizer-based approach, balance equations are posed as direct constraints to the optimizer. In the flow solver-based approach, balance equations are satisfied within the flow solver evaluation. These approaches are applied to a flying wing case, where blended trailing edge deflection is used to control the pitching moment. The wing is treated as rigid, and lift and pitching moment balance equations are taken into account for trimming. Tests are performed with varying numbers of shape design parameters and with varying numbers of flight points. It is concluded that the flow solver-based approach performs more robustly, and thus should be preferred in general, even though it may take more time than the optimizer-based approach

Reduced order models for aerodynamic applications, loads and MDO

Reduced Order Models (ROMs) have found widespread application in fluid dynamics and aerodynamics. In their direct application to Computational Fluid Dynamics (CFD) ROMs seek to reduce the computational complexity of a problem by reducing the number of degrees of freedom rather than simplifying the physical model. Here, parametric nonlinear ROMs based on high-fidelity CFD are used to provide approximate flow solutions, but at lower evaluation time and storage than the original CFD model. ROMs for both steady and unsteady aerodynamic applications are presented. We consider ROMs combining proper orthogonal decomposition (POD) and Isomap, which is a manifold learning method, with interpolation methods as well as physics-based ROMs, where an approximate solution is found in the POD-subspace by minimizing the corresponding steady or unsteady flow-solver residual. In terms of the nonlinear unsteady least-squares ROM algorithm, we present the details of an improved accelerated greedy missing point estimation procedure which is usedin the online phase to select a subset of the unsteady residual for reasons of computational efficiency during the online prediction phase. The issue of how to best train the ROM with high-fidelity CFD data is also addressed. The goal is to train ROMs that yield a large domain of validity across all parameters and flow conditions at the expense of a relatively small number of CFD solutions. The different ROM methods are demonstrated on a wide-body transport aircraft configuration at transonic flow conditions. The steady ROMs are used to predict the static aeroelastic loads in the context of multidisciplinary optimization (MDO), where a structural model is to be sized for the (aerodynamic) loads. They are also used in a process where an a priori identification of the most critical static load cases is of interest and the sheer number of load cases to be considered does not lend itself to high-fidelity CFD. The unsteady nonlinear least-squares ROM approach is applied to modeling discrete gusts of different amplitude and length in the context of rapid evaluation of gust-induced air loads

Contamination of plants, soil, and building stones at a Roman heritage archaeological site in an urban area

Some cultural heritage sites in Jordan are in urban areas being exposed to anthropogenic pollution. Therefore, it is important to evaluate the contamination at these sites to protect them. Here, we considered a Roman archeological site (Nymphaeum) situated in Amman. The contamination in soil, plants, and building stones did not show spatial distribution within the site. The contamination was the highest in soil (heavy metals 10(4) -10(7) ppb and sulfur similar to 3.5x10(6) ppb) whereas in plants was the least for Cr (similar to 400 ppb) and in building stones it was the least for Cu (similar to 860 ppb). The highest contamination in plants and building stones was found for Al (similar to 5x10(4) and similar to 6.2x10(5) ppb respectively). The sulfur content in plants (similar to 7.6x10(5) ppb) was higher than that in the building stones (similar to 2.3x10(5) ppb). The heavy metals and sulfur contamination in the building stones were lower than what was reported elsewhere outside Jordan.Peer reviewe

Antifouling polymeric nanocomposite membrane based on interfacial polymerization of polyamide enhanced with green TiO2 nanoparticles for water desalination

In the present investigation, the preparation and characterization of polyamide/TiO2 as thin film nanocomposites (TFN) for brackish water desalination was investigated. TiO2 nanoparticles (NPs) were synthesized by a green method using thyme plant extract as a reducing and capping agent. The TiO2 NPs was successfully prepared in pure crystalline anatase phase with 15 nm size, and −33.1 mV zeta potential. The antimicrobial tests confirmed the antimicrobial activity of TiO2 against gram-positive and gram-negative bacteria. In addition, TiO2 NPs showed a good photocatalytic activity in degradation of methylene blue dye. TFN based on interfacial polymerization was enhanced by embedding 5% of the greenly synthesized TiO2 NPs within the polyamide thin film active layer. The incorporation of TiO2 NPs was confirmed by SEM, atomic force microscope (AFM), surface wettability, and FTIR. Membranes performance was investigated based on flux, salt rejection and fouling resistance. The antifouling was examined using bovine serum albumin (BSA) as protein fouling by dead-end cell filtration system at 2 bar. The results showed the TFN increased in water flux by 40.9% and a slight decrease in NaCl rejection (6.3%) was observed, with enhancement in antifouling properties. The flux recovery rate of the modified TFN membranes after fouling with BSA solution was enhanced by 21.5% (from 61.7% for TFC to 83.2% for TFN). Also, they demonstrated remarkable anti-biofouling behavior against both bacterial strains

E/Z reversible photoisomerization of methyl orange doped polyacrylic acid-based polyelectrolyte brush films

The photoswitching behavior of the polyacrylic acid (PAA) doped by methyl orange (MO) brush film was investigated using spectral analysis of UV-Vis absorbance, Fourier Transformation Infrared spectroscopy, 2D electrical conductivity mapping and Atomic Force Microscopy. The kinetics and time evolution of the photoisomerization of the PAA-MO PEBs film from E-state to Z-state by UV-light irradiation, and reverse thermal relaxation to E-state was explored. The results confirm that the photoisomerization kinetics of the overall peak is the superposition of the photoisomerization kinetics of (Formula presented.) transition, low- and high-frequency of the (Formula presented.) transition bands. The E–Z transformation led to transforming the azobenzene from flat with no dipole moment to 3.0 D dipole moment. Hence, the electrical conductivity escalated accordingly. The transformation of E-state to Z-state led to the collapse of the formed brushes because of the angular rotational momentum consequent to E–Z isomerization

The COVID-19 pandemic may force the world to reflect on the pre pandemic style of life

Introduction: The COVID-19 pandemic has caused a lot of changes on an individual and societal level. The current study was designed to investigate the impact of the isolation/ social distancing period on people’s sense of Being, Belonging and Becoming in the early stages of the COVID-19 measures. Methods: A cross sectional survey study design was employed using a researcher-developed questionnaire with items developed based on the Model of Occupational Wholeness to investigate the changes that may have happened to what people have been doing during the COVID-19 measures compared to the time before. A sample of 1206, using snowball sampling, responded to the online questionnaire. Results: Findings indicated that participants at the early stage of the COVID-19 pandemic had changed the pattern of their Doings. The change of pattern, which was considered positive, was in relation to people valuing their health, having more time to take care of themselves, and doing activities which they had never had enough time to do before. Conclusions: While these findings are not generalizable, they provide some insights into how the post-pandemic lifestyle of many people does not permit doing a lot of activities that could help with their health and well-being. While enforced isolation may have negative consequences, it is also clear that the pre COVID-19 pandemic lifestyle did not fully support healthy living. Reflecting on the COVID-19 lockdown experience provides an opportunity to review what are the essential personal and societal elements for living a healthy life

Effect of biochar modified with magnetite nanoparticles and HNO\u3csub\u3e3\u3c/sub\u3e for efficient removal of Cr(VI) from contaminated water: A batch and column scale study

© 2020 Elsevier Ltd Chromium (Cr) poses serious consequences on human and animal health due to its potential carcinogenicity. The present study aims at preparing a novel biochar derived from Chenopodium quinoa crop residues (QBC), its activation with magnetite nanoparticles (QBC/MNPs) and strong acid HNO3 (QBC/Acid) to evaluate their batch and column scale potential to remove Cr (VI) from polluted water. The QBC, QBC/MNPs and QBC/Acid were characterized with SEM, FTIR, EDX, XRD as well as point of zero charge (PZC) to get an insight into their adsorption mechanism. The impact of different process parameters including dose of the adsorbent (1–4 g/L), contact time (0–180 min), initial concentration of Cr (25–200 mg/L) as well as solution pH (2–8) was evaluated on the Cr (VI) removal from contaminated water. The results revealed that QBC/MNPs proved more effective (73.35–93.62-%) for the Cr (VI) removal with 77.35 mg/g adsorption capacity as compared with QBC/Acid (55.85–79.8%) and QBC (48.85–75.28-%) when Cr concentration was changed from 200 to 25 mg/L. The isothermal experimental results follow the Freundlich adsorption model rather than Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherm models. While kinetic adsorption results were well demonstrated by pseudo second order kinetic model. Column scale experiments conducted at steady state exhibited excellent retention of Cr (VI) by QBC, QBC/MNPs and QBC/Acid at 50 and 100 mg Cr/L. The results showed that this novel biochar (QBC) and its modified forms (QBC/Acid and QBC/MNPs) are applicable with excellent reusability and stability under acidic conditions for the practical treatment of Cr (VI) contaminated water

Epidemiology of Chlamydia trachomatis in the Middle East and north Africa: a systematic review, meta-analysis, and meta-regression.

BACKGROUND: The epidemiology of Chlamydia trachomatis in the Middle East and north Africa is poorly understood. We aimed to provide a comprehensive epidemiological assessment of C trachomatis infection in the Middle East and north Africa. METHODS: We did a systematic review of C trachomatis infection as well as a meta-analysis and meta-regression of C trachomatis prevalence. We searched PubMed and Embase, as well as regional and national databases up to March 13, 2019, using broad search terms with no language or year restrictions. Any document or report including biological measures for C trachomatis prevalence or incidence was eligible for inclusion. We extracted all measures of current (genital or rectal), recent, and ever infection with C trachomatis. We estimated pooled average prevalence in different populations using random-effects meta-analysis. Factors associated with prevalence and sources of between-study heterogeneity were determined using meta-regression. FINDINGS: We identified a total of 1531 citations, of which 255 reports contributed to 552 C trachomatis prevalence measures from 20 countries. No incidence measures were identified. Pooled prevalence of current genital infection was 3·0% (95% CI 2·3-3·8) in general populations, 2·8% (1·0-5·2) in intermediate-risk populations, 13·2% (7·2-20·7) in female sex workers, 11·3% (9·0-13·7) in infertility clinic attendees, 12·4% (7·9-17·7) in women with miscarriage, 12·4% (9·4-15·7) in symptomatic women, and 17·4% (12·5-22·8) in symptomatic men. Pooled prevalence of current rectal infection was 7·7% (4·2-12·0) in men who have sex with men. Substantial between-study heterogeneity was found. Multivariable meta-regression explained 29·0% of variation. Population type was most strongly associated with prevalence. Additional associations were found with assay type, sample size, country, and sex, but not with sampling methodology or response rate (about 90% of studies used convenience sampling and >75% had unclear response rate). There was no evidence for temporal variation in prevalence between 1982 and 2018. INTERPRETATION: C trachomatis prevalence in the Middle East and north Africa is similar to other regions, but higher than expected given its sexually conservative norms. High prevalence in infertility clinic attendees and in women with miscarriage suggests a potential role for C trachomatis in poor reproductive health outcomes in this region. FUNDING: National Priorities Research Program from the Qatar National Research Fund (a member of Qatar Foundation)

Shape Optimization Using the Aero-structural Coupled Adjoint Approach for Viscous Flows

The aero-structural coupled adjoint approach here is an efficient approach to compute the gradients of the aerodynamic coefficients obtained from coupled fluid-structure simulations. These gradients can then be advantageously employed for gradient-based optimizations. In this study, the approach is extended for the first time to tackle viscous flows. After introducing the theory, the method is applied to optimize the flight shape of two realistic 3D configurations. In both applications, the coupled adjoint approach permits to decrease the drag at constant lift with limited computational effort