Passive control of instability of flexible panels in a mean flow

A hybrid of theoretical and computational methods is developed and used to show that localised stiffness added to flexible panels can reduce their susceptibility to flow-induced damage caused by static- and flutter-type instabilities of the panel. Both two- and three-dimensional flow-structure systems are studied with the added stiffness respectively introduced by added springs or a narrow stiffening strip. For two-dimensional systems, a genetic algorithm is developed to optimise the positioning of the added stiffness

Triboelectric behaviour of selected zeolitic-imidazolate frameworks: exploring chemical, morphological and topological influences †

Tribo- and contact electrification remain poorly understood, baffling and discombobulating scientists for millennia. Despite the technology needed to harvest mechanical energy with triboelectric generators being incredibly rudimentary and the fact that a triboelectric output can be obtained from almost any two material combinations, research into triboelectric generator materials typically focuses on achieving the highest possible output; meanwhile, understanding trends and triboelectric behaviours of related but lower performing materials is often overlooked or not studied. Metal–organic frameworks, a class of typically highly porous and crystalline coordination polymers are excellent media to study to fill this knowledge gap. Their chemistry, topology and morphology can be individually varied while keeping other material properties constant. Here we study 5 closely related zeolitic-imidazolate type metal–organic frameworks for their triboelectric performance and behaviour by contact-separating each one with five counter materials. We elucidate the triboelectric electron transfer behaviour of each material, develop a triboelectric series and characterise the surface potential by Kelvin-probe force microscopy. From our results we draw conclusions on how the chemistry, morphology and topology affect the triboelectric output by testing and characterising our series of frameworks to help better understand triboelectric phenomena

Numerical Investigation of Low-Salinity Waterflooding Capability to Enhanced Oil Recovery

Low-salinity water flooding (LSWF) is one of techniques that can be used to improve oil production and has gained a significant attention in these days because of its advantages over conventional water flooding and chemical flooding. Even though many mechanisms have been recommended on an extra oil recovery achieved using LSWF process, the principle fundamental of the mechanism is still not fully understood. This research paper investigates the potential of oil recovery in an onshore sandstone reservoir using LSWF. A field-scale three–dimensional reservoir model has been developed via CMG’s GEM compositional simulator where the model validated against a real production field data that were in good agreement with a deviation value of 8%. The primary mechanism of LSWF has been identified by providing incremental oil recovery due to a multi-component ion exchange mechanism that causes wettability alteration of reservoir rock from oil-wet to water-wet. The sensitivity study showed that LSWF provides a higher accumulative oil production compared to conventional high salinity water injection with 13.5 and 12 MMSTB. Moreover, the early time of low saline brine injection can provide a maximum oil recovery up to 71%. Therefore, implementing this scenario immediately after the primary recovery, it provides production benefits in both secondary and tertiary method. The oil recover factor increased to 75.5% with the increasing of brine injection rate up to an optimum value of 5320 bbl/d. A reservoir temperature also influenced the ion exchange wettability alteration during LSWF in which as the temperature increasing enhances the oil recovery. Therefore, a high temperature sandstone reservoir will be a potential candidate for LSWF

Laboratory Evaluation of Low to Medium Cost Particle Sensors

Low cost instruments for particulate matter monitoring directly benefits researchers, governments, and public with the overall goal of reducing the adverse effects of air pollution. As a result, companies have been rushing to produce such products. While laser light scattering is a low cost method, the technique suffers from drawbacks with accuracy. The performance of sensors on the market are questionable as few have been scientifically analyzed and the public lacks the technical means of verifying accuracy themselves. Thus, the objective of this research was to validate the performance of commercial laser light scattering based particle sensors. To accomplish this, eight were evaluated against a reference instrument and the relationship was modeled. Afterwards, a custom apparatus with improved calibration was developed for particulate monitoring. The eight commercial sensors evaluated demonstrated high linearity with the reference instrument, but poor estimations of actual particulate concentrations. The performance of the sensors was strongly dependent on particle composition and size. Statistical analysis was also completed to compare linear parametric models used to calibrate the sensors with the non-parametric model. Results show that the linear models were frequently biased and therefore higher order polynomials should be used. The custom apparatus was further evaluated with several laboratory particle sources as well as in real environments. Results show a low dependence on aerosol composition with higher flow rates. The instrument was calibrated to provide an "average" response for the tested particles. Models were developed for PM10 and PM2.5 number and mass concentration measurements. The 95% prediction interval for PM10 and PM2.5 number concentration was +/-350 and +/-360 particles/cm3, respectively. For PM10 and PM2.5 mass concentration, the intervals were +/-75 and +/-45 μg/m3, respectively