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Experimental study on structure responses of triple wing sails to turbulence flows at multiple apparent wind angles
No full textWind-assisted propulsion for ships represented by wingsails is booming in today’s world. The cross-sectional shapes of wingsails are usually NACA profiles without camber, but a recent technology is to use crescent-shaped profiles with camber for remarkably higher aerodynamic lift. Unlike conventional NACA foils, the crescent-shaped foil has not deserved sufficient research regarding its structure responses to turbulence. In this paper, the structures of triple-lined-up crescent-shaped foils are investigated in wind-tunnel (WT) tests a scale on 1:100 compared to the full-size configurations. A wide range of apparent wind angles and wind speeds of interest are studied, to find out the critical angles and the best/worst performance points. Digital Image Correlation (DIC) is used to measure structural vibrations. Spectral analysis of the structural vibrations is performed to understand the coupled effects between the flow and the structures. The results can be used to guide the practical design of wing sails
Mapping Maintenance Related Information Using the MIMOSA CRIS Standard: A Case Study Within Gravel Road Maintenance
No full textThe efficient maintenance of gravel roads depends on digital tools and data as well as information systems adapted for specific needs while conforming with current standards for better interconnectivity. Within gravel road maintenance, cloud-based solutions are a key alternative. This because necessary information, such as road condition data, could be shared throughout the network and provide the opportunity to coordinate maintenance activities between stakeholders. Effective standards are essential since they permit various services with the ability to work together while at the same time supporting differences that ease competition and innovation. Among several maintenance standards, the OSA-CBM and MIMOSA CRIS database schema are intended for handling information exchange and communication within and between systems supporting condition-based maintenance. This paper tests the usability of these standards for translating context-dependent information into a standardized data set. The domain studied is gravel road maintenance. Critical data was gathered and elicited from different stakeholders and represented in the form of a conceptual information model. This paper exemplifies how the conceptual model could be mapped into a logical model with respect to the CRIS information model. The main results are in the form of a conceptual and logical information model for purposes of gravel road maintenance, as well as a procedure suggested for mapping the information model following specific steps
Synthetic turbulence generator for the wall-modeled LES lattice Boltzmann method
No full textThe synthetic turbulence generator (STG) lies at the interface of the Reynolds averaged Navier-Stokes (RANS) simulation and large eddy simulation (LES). This paper presents a STG for the multiple-relaxation-time(MRT) lattice Boltzmann method(LBM) framework at high friction Reynolds numbers, with consideration of near wall modeling. The Reichardt wall law, in combination with a force-based method, is used to model the near wall field. The STG wall-modeled(STG-WM) LES results are compared with turbulent channel flow simulations at\ua0\ua0at different resolutions. The results demonstrate good agreement with DNS, with the adaptation length of 6 to 8 boundary layer thickness. This method has a wide range of potentials for hybrid RANS/LES-LBM related applications at high friction Reynolds numbers
HighLight: Towards an Ambient Robotic Table as a Social Enabler
Get PDFWith smartphones becoming more commonplace in our daily lives, they often take up more time and space than we would like them to. Research shows that using smartphones during social interactions does more harm than good. With this in mind, we set out to create the first prototype of an ambient robotic table that will support social interactions and discourage digital distractions. Through a rapid prototyping process, we present HighLight, a prototype of a socially enabling robotic table that has a smartphone compartment in its center and ambient features reacting in real-time to conversations taking place around the table. We report on our contributions to the research community by investigating the design of an ambient robotic table as a social enabler that encourages social interactions through ambiance, thus exploring future directions of non-disruptive technologies that support social interactions
An energy-based deep splitting method for the nonlinear filtering problem
Get PDFThe purpose of this paper is to explore the use of deep learning for the solution of the nonlinear filtering problem. This is achieved by solving the Zakai equation by a deep splitting method, previously developed for approximate solution of (stochastic) partial differential equations. This is combined with an energy-based model for the approximation of functions by a deep neural network. This results in a computationally fast filter that takes observations as input and that does not require re-training when new observations are received. The method is tested on four examples, two linear in one and twenty dimensions and two nonlinear in one dimension. The method shows promising performance when benchmarked against the Kalman filter and the bootstrap particle filter
A one-carbon chemicals conversion strategy to produce precursor of biofuels with Saccharomyces cerevisiae
No full textUtilization of one-carbon chemicals such as CO2, formate, and methanol by microorganisms can enable the sustainable production of fuels and chemicals. However, the low conversion efficiency of these chemicals by microorganisms is a major challenge. To address this, we designed a one-carbon strategy that can utilize CO2 and its derivative formate. Here, a platform yeast strain with improved formate utilization and NAD(P)H production was constructed and evaluated for its ability to produce free fatty acids (FFAs). Based on 13C-marked analysis, the one-carbon assimilation efficiency of the platform strain reached 11.24%. Through continuous optimization, under conditions of glucose feeding the formate utilization rate of the final strain reached 0.48 g/L/h, with the final titer of FFAs reached 10.1 g/L, which represented improvements of 21.8 times and 33.7 times, respectively. As such, the produced FFAs can be easily transformed into biodiesel by combining them with downstream technologies in future research
Strain-level bacterial typing directly from patient samples using optical DNA mapping
Get PDFFor bacterial infections, it is important to rapidly and accurately identify and characterize the type of bacteria involved so that optimal antibiotic treatment can be given quickly to the patient. However, current diagnostic methods are sometimes slow and cannot be used for mixtures of bacteria. We have, therefore, developed a method to identify bacteria directly from patient samples. The method was tested on two common species of disease-causing bacteria - Escherichia coli and Klebsiella pneumoniae - and it could correctly identify the bacterial strain or subtype in both urine samples and mixtures. Hence, the method has the potential to provide fast diagnostic information for choosing the most suited antibiotic, thereby reducing the risk of death and suffering. Nyblom, Johnning et al. develop an optical DNA mapping approach for bacterial strain typing of patient samples. They demonstrate rapid identification of clinically relevant E. coli and K. pneumoniae strains, without the need for cultivation. BackgroundIdentification of pathogens is crucial to efficiently treat and prevent bacterial infections. However, existing diagnostic techniques are slow or have a too low resolution for well-informed clinical decisions.MethodsIn this study, we have developed an optical DNA mapping-based method for strain-level bacterial typing and simultaneous plasmid characterisation. For the typing, different taxonomical resolutions were examined and cultivated pure Escherichia coli and Klebsiella pneumoniae samples were used for parameter optimization. Finally, the method was applied to mixed bacterial samples and uncultured urine samples from patients with urinary tract infections.ResultsWe demonstrate that optical DNA mapping of single DNA molecules can identify Escherichia coli and Klebsiella pneumoniae at the strain level directly from patient samples. At a taxonomic resolution corresponding to E. coli sequence type 131 and K. pneumoniae clonal complex 258 forming distinct groups, the average true positive prediction rates are 94% and 89%, respectively. The single-molecule aspect of the method enables us to identify multiple E. coli strains in polymicrobial samples. Furthermore, by targeting plasmid-borne antibiotic resistance genes with Cas9 restriction, we simultaneously identify the strain or subtype and characterize the corresponding plasmids.ConclusionThe optical DNA mapping method is accurate and directly applicable to polymicrobial and clinical samples without cultivation. Hence, it has the potential to rapidly provide comprehensive diagnostics information, thereby optimizing early antibiotic treatment and opening up for future precision medicine management
Performance analysis of sustainable technologies for biochar production: A comprehensive review
Get PDFBiochar is a valuable product from thermochemical energy conversion technologies. Its yield, and properties vary vastly with the type of feedstock, technology and operating parameters applied, which also affect potential applications. Hence, in this paper various sustainable technologies for biochar production including slow pyrolysis, fast pyrolysis, intermediate pyrolysis, torrefaction, microwave, gasification, flash carbonization, and hydrothermal carbonization are reviewed, with a focus on performance analysis. Specifically, the relationships between biochar production technologies, biochar properties, and the applied feedstocks and operating conditions for each technology are discussed. The effect of critical operating parameters e.g., temperature and heating rate on the yield and quality of the biochar produced via these systems are also studied. This review provides researchers and energy decision makers, important information regarding to the most efficient pathways from feedstocks to biochar products by implementing of sustainable biochar production technologies
Multilevel three-phase dual active bridge dc-dc converters - A study on converter modulation, capacitive energy requirement, ZVS boundaries, MFT\u27s winding connections, and core losses
No full textThe collection and transmission of power from offshore wind turbines using dc have advantages over the ac system. One of the enabling technologies for deploying dc collection is the dc-dc converter that boosts the dc output from the turbine to the medium-voltage dc level of the collection grid. This dc-dc converter should be able to transfer nominal power of at least 15 MW, boost the voltage from a few kilovolts to tens of kilovolts, have high power density and efficiency. The dual active bridge (DAB) converter concept is a suitable candidate for this application. It comprises two active inverters and an intermediate transformer which provides galvanic isolation and voltage matching between the LV and MV systems. Its soft-switching capabilities allow an increase in the switching frequency without deteriorating the efficiency of the converter. Therefore, the size of passive components can be reduced to achieve high power densities.Using partial power processing DAB converters for this application has been studied extensively in the literature, while this document considers bulk power transmission using multilevel converter topologies focusing on three-phase topologies. Different aspects of the converters are studied in detail, including; desired leakage inductance of the transformer; capacitive energy storage requirement of the converters; the lifetime of semiconductors; the effect of winding configurations; the flux waveforms inside the transformer core; the transformer\u27s core losses; the soft-switching boundaries; and harmonic and partial load performance. Mathematical models are developed for different studies and verified by simulations or measurements.Several converter topologies and winding configurations are studied. As an example, it is shown that a three-phase DAB with YD winding configuration, controlled transition bridge converter, and quasi-two-level (Q2L) modulation is the best choice for this application. A modulation strategy is proposed to improve the partial load performance. A loss split calculation showed that the semiconductor losses decreased by 94% and 81% at 5% and 10% of the nominal power, respectively, compared to the Q2L modulation
Application of geopolymers for treatment of industrial solid waste containing heavy metals: State-of-the-art review
No full textMetallurgy, mineral processing, waste disposal, and other industries produce large amounts of industrial solid waste containing heavy metals (ISWCHM), which poses a serious threat to the ecological environment. Geopolymers are aluminosilicate inorganic polymers that have the advantages of high strength, good corrosion resistance, and low carbon emission during production. The use of ISWCHM to prepare geopolymers can simultaneously utilize solid waste resources and solidify heavy metals. In this paper, the latest research progress in the preparation of geopolymers from ISWCHM is reviewed, including the preparation techniques, application and solidification/stabilization mechanisms of heavy metals. In addition, we analyze existing research problems and provide an outlook on future research and development directions