A map and a pipe : a new approach to characterizing erosion-corrosion regimes of Fe in three dimensions using CFD modelling

In studies of erosion-corrosion, much work has been carried out in recent years to identify regimes of behaviour. Such regimes describe the transition between the erosion and corrosion dominated mechanisms. They can also be used, by assigning various criteria, to identify other regimes of behaviour such as extent of "synergy/antagonism" in the process, so-called "additive" behaviour and the extent of wastage. Despite this work, there has been very little effort to combine the two dimensional erosion-corrosion map with CFD modelling approaches, in which the characteristics of the fluid are accounted for in the regime description. This means that extrapolation of such maps in two dimensions to a three dimensional real surface presents some difficulties. However, it is these surfaces that corrosion engineers are required to tailor, either through modification of the material composition, the surface or the process parameters, for optimum erosion-corrosion resistance. In this paper, a methodology is generated to combine the concepts of CFD modelling, and the erosion-corrosion regime map for a specific geometry and for a range of pure metals in descending order in the Galvanic series. The changes in regimes are presented as a function of variation in the erosion and corrosion variables i.e. particle size, hardness and solution pH. Erosion-corrosion regimes are presented, based on the model results, showing the wide range of mechanistic and wastage mechanisms possible over the component surface

Improving the Torsional Strength of Reinforced Concrete Hollow Beams Strengthened with Externally Bonded Reinforcement CFRP Stripe Subjected to Monotonic and Repeated Loads

The loading on bridges, ports, multi-story parking garages, airport facilities, and many other structures is often repeated and usually built with reinforced concrete beams. The behavior of concrete under repeated loads differs from that of static loads. Due to the loading and unloading process, repeated loads cause crushing in some concrete sections. The war and other events damaged numerous concrete structures and bridges in Iraq. Therefore, maintenance and rehabilitation of these structural parts are already required. This study aims to illustrate the behaviour of reinforced concrete hollow beams strengthened with a strip of carbon fiber reinforced polymer (CFRP) in various configurations using the externally bonded reinforcement (EBR) method when exposed to monotonic and repeated torsion. Eight beams of 250 x 350 x 3000 mm were cast and tested up to failure under pure torsion. Two of these beams were unreinforced. Other beams were strengthened with varied configurations of CFRP strips. The tested specimens were divided into two groups. For each investigation condition, the beam was examined under monotonic torsion and utilized as a control for those examined under repeated torsion after seven cycles of 60% of the control samples ultimate loads. Using the CFRP stripe, the torsional performance of the reinforced concrete beams was greatly enhanced. Test beams reinforced with two continuous CFRP stripes demonstrated a more significant increase in the ultimate torsional moment than beams strengthened with other CFRP stripe configurations. Beams tested under repeated torsion show less degradation in torsional strength than beams tested under monotonic torsion moment

Inhibiting sulphate attack on concrete by hydrophobic green plant extract

Organic base (Amine) and inorganic base (Nitrite) have been known for protection of concrete structures but are not commercially indigenous to most developing economies due to manufacturing difficulties and are toxic to the environment. Also inhibitors are not known to stop sulphate attack in concrete. Hence, the objective of the present investigation was to study a novel, eco-friendly and hydrophobic green plant extracts inhibitor and compares its effectiveness with established calcium nitrite and ethanolamine inhibitors. Bambusa Arundinacea (Green plant extracts), calcium nitrite and ethanolamine corrosion inhibitors were selected for the present investigation. Compressive strength of 100×100×100mm concrete cubes after 7, 28 and 90 days of curing test was used. The results of the inhibitors studied showed that Bambusa Arundinacea has superior compressive strength compared to calcium nitrite and ethanolamine. Bambusa Arundinacea may be considered a better substitute for nitrite and amine- based corrosion inhibiting admixtures for durable concrete structures due its pore blocking effects

Studies on the effects of 6-Benzylaminopurine and 1-Naphthaleneacetic acid on the in vitro regeneration of okra (Abelmoschus esculentus l.)

Okra is an important vegetable crop which belongs to the family Malvaceae. Experiments were created to study the effects of varying concentrations of Plant Growth Regulators (PGRs) on the in vitro propagation of okra using seed explants. The seeds were cultured in vitro on Murashige and Skoog (MS) basal media containing 30% sucrose, 0.9% agar and different concentrations (0.1mg/L to 0.25mg/L) of auxin (NAA) and cytokinin (BAP) singly and in combination. Early germination was obtained at 0.25mg/L BAP and 0.25mg/L NAA. Highest height was recorded at 0.15mg/L (12.8cm) followed by a combination of 0.25mg/L BAP and 0.25mg/L NAA (4.91cm). 0.15mg/L NAA followed by a combination of 0.25mg/L NAA and 0.25mg/L BAP and 0.1mg/L BAP and 0.1mg/L NAA in combination gave best vigor. Similarly, full strength media supplemented with 0.15mg/L NAA followed by 0.25mg/L BAP and 0.25mg/L NAA and 0.1mg/L BAP and 0.1mg/L NAA in combination gave the highest number of leaves. Similarly, 0.1mg/L NAA and a combination treatments of 0.1mg/L BAP and 0.1mg/L NAA with 0.25mg/L BAP and 0.25mg/L NAA gave the best percentage germination at 25%. Results of Analysis Of Variance (ANOVA) indicated significant differences among the treatments compared with the control which did not respond p < 0.05. The protocol developed in this present study can be used for large scale seedling formation and biomass production of okra. It can also be used to obtain sterile and uniform materials for various in vitro studies for the improvement of okra

Triangle of Safety Technique: A New Approach to Laparoscopic Cholecystectomy

Backgrounds and Study Aims. Common bile duct (CBD) injury is one of the most serious complications of laparoscopic cholecystectomy (LC). Misidentification of the CBD during dissection of the Calot's triangle can lead to such injuries. The aim of the authors in this study is to present a new safe triangle of dissection. Patients and Method. 501 patients under went LC in the following approach; The cystic artery is identified and mobilized from the gall bladder (GB) medial wall down towards the cystic duct which would simultaneously divide the medial GB peritoneal attachment. This is then followed by dividing the lateral peritoneal attachment. The GB will be unfolded and the borders of the triangle of safety (TST) are achieved: cystic artery medially, cystic duct laterally and the gallbladder wall superiorly. The floor of the triangle is then divided to delineate both cystic duct and artery in an area relatively far from CBD. Results. There were little significant immediate or delayed complications. The mean operating time was 68 minutes, nearly equivalent to the conventional method. Conclusions. Dissection at TST appears to be a safe procedure which clearly demonstrates the cystic duct and may help to reduce the CBD injuries

LICA-CS: Efficient Lossless Image Compression Algorithm via Column Subtraction Model

Driven by the unprecedented amount of data generated in the last few decades, data storage and communication are becoming more challenging. Although many approaches in data compression have been developed to alleviate these challenges, more efforts are still needed, especially for lossless image compression, which is a promising technique when critical information loss is not allowed. In this paper, we propose a new algorithm called the Lossless Image Compression Algorithm using a Column Subtraction model (LICA-CS). LICA-CS is efficient, low in complexity, decreases the image bit-depth, and enhances state-of-the-art performance. LICA-CS first implements a color transformation method as a pre-processing phase, which strategically minimizes inter-channel correlations to optimize compression outcomes. After that, a novel subtraction method was developed to compress the image data column-wise. We tackle the similarity and proximity of pixel values within adjacent columns, which offers a distinct advantage in reducing image size observing a significant size reduction of 71%. This is achieved through the subtraction of neighboring columns. The conducted experiments on colored images show that LICA-CS outperforms existing algorithms in terms of compression rate. Moreover, our method exhibited remarkable enhancements in execution time, with compression and decompression processes averaging 1.93 seconds. LICA-CS advances the state-of-the-art in lossless image compression, promising enhanced efficiency and effectiveness in image compression technologies

Inferring epidemic dynamics using Gaussian process emulation of agent-based simulations

Computational models help decision makers understand epidemic dynamics to optimize public health interventions. Agent-based simulation of disease spread in synthetic populations allows us to compare and contrast different effects across identical populations or to investigate the effect of interventions keeping every other factor constant between ``digital twins''. FRED (A Framework for Reconstructing Epidemiological Dynamics) is an agent-based modeling system with a geo-spatial perspective using a synthetic population that is constructed based on the U.S. census data. In this paper, we show how Gaussian process regression can be used on FRED-synthesized data to infer the differing spatial dispersion of the epidemic dynamics for two disease conditions that start from the same initial conditions and spread among identical populations. Our results showcase the utility of agent-based simulation frameworks such as FRED for inferring differences between conditions where controlling for all confounding factors for such comparisons is next to impossible without synthetic data.Comment: To be presented in Winter Simulation Conference 2023, repository link: https://github.com/abdulrahmanfci/gpr-ab

Estimating Treatment Effects Using Costly Simulation Samples from a Population-Scale Model of Opioid Use Disorder

Large-scale models require substantial computational resources for analysis and studying treatment conditions. Specifically, estimating treatment effects using simulations may require a lot of infeasible resources to allocate at every treatment condition. Therefore, it is essential to develop efficient methods to allocate computational resources for estimating treatment effects. Agent-based simulation allows us to generate highly realistic simulation samples. FRED (A Framework for Reconstructing Epidemiological Dynamics) is an agent-based modeling system with a geospatial perspective using a synthetic population constructed based on the U.S. census data. Given its synthetic population, FRED simulations present a baseline for comparable results from different treatment conditions and treatment conditions. In this paper, we show three other methods for estimating treatment effects. In the first method, we resort to brute-force allocation, where all treatment conditions have an equal number of samples with a relatively large number of simulation runs. In the second method, we try to reduce the number of simulation runs by customizing individual samples required for each treatment effect based on the width of confidence intervals around the mean estimates. In the third method, we use a regression model, which allows us to learn across the treatment conditions such that simulation samples allocated for a treatment condition will help better estimate treatment effects in other conditions. We show that the regression-based methods result in a comparable estimate of treatment effects with less computational resources. The reduced variability and faster convergence of model-based estimates come at the cost of increased bias, and the bias-variance trade-off can be controlled by adjusting the number of model parameters (e.g., including higher-order interaction terms in the regression model).Comment: To be presented in IEEE International Conference on Biomedical and Health Informatics 2023, repository link: https://github.com/abdulrahmanfci/intervention-estimatio

Evaluation of Sheanut Shell-Reinforced Automotive Brake Pad

For over a century now, asbestos has been used as friction material in the manufacture of brake pads but its use is currently been avoided due to its carcinogenic nature and potential to cause cancer. This study is focused on development of a new brake pad using sheanut shell (SNS) which is an eco-friendly material as the reinforcement and epoxy resin as the binder. Other constituents used are calcium carbonate (CaCO3), graphite and aluminium oxide (Al2O3). Five compositions were formulated with the epoxy resin and reinforcement varied at interval of 5 wt% while CaCO3, graphite and Al2O3 remain constant at 30, 10 and 10 wt% respectively. The developed brake pads were subjected to compressive, abrasive and water absorption tests while their densities were also measured. The results showed that the compressive strength, abrasive strength and the density of the samples decreased as the reinforcement content increased while the water absorption rate increased as the reinforcement content increased. The value of the compressive strength ranged from 64.88 – 93.04Mpa, wear rate from 3.13 – 6.25mg/m, water absorption from 0.899 – 2.722% and density from 0.764 – 1.487g/m3. The result of this research indicates that SNS particles can be used as a replacement for asbestos in brake pad production

Combustion Modeling of a Fixed Bed Downdraft Biomass Gasifier Using Computational Fluid Dynamics Design

Thermochemical conversion of biomass in a gasifier for the production of syngas provides the enabling technology for efficient biomass resource utilization. Gasification is a complex process involving the interactions of numerous parameters, hence CFD tool is usually utilized to numerically optimize the design and operation of the gasifier reactor for improved performance. The gasification of multiple biomass usually requires a complex set of facilities for experimental set up in order to determine the optimum operating conditions for maximum gas yield. When this is not available, it can pose a bottle-neck to process development and optimization.  In this study, the GAMBIT and FLUENT were used to model and simulate the gasifier reactor with emphasis on the combustion and gasification (reduction) zones in order to maximize the thermal output of the combustor by an optimization of biomass fuel types. Model validation was achieved by showing a close agreement between numerical and experimental results within the same configuration, particularly to show the effect of temperature on the gasification of Fixed Bed Downdraft gasifier. The fraction of initial moisture content, air flow rate, temperature of the pyrolysis zone, and chemical composition of the biomass were the required input data for the model to predict the gasification temperature. Computations were carried out for rice husk, saw dust and corn cobs as gasifier fuels, whereby air was used as the oxidizing agent. The porosity and oxidizer velocity were varied between 0.1 – 0.5 and 5 – 15 m/s respectively. The predicted results compared with experimental data showed good agreement. The simulated temperature gradient also indicated that rich fuel combustion zone was greater for rice husk - corn cobs, an indication that improved gasification and pyrolysis were present