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Review of Suspended Sediment Transport Mathematical Modelling Studies
No full textYesThis paper reviews existing studies relating to the assessment of sediment concentration profiles within various flow conditions due to their importance in representing pollutant propagation. The effects of sediment particle size, flow depth, and velocity were considered, as well as the eddy viscosity and Rouse number influence on the drag of the particle. It is also widely considered that there is a minimum threshold velocity required to increase sediment concentration within a flow above the washload. The bursting effect has also been investigated within this review, in which it presents the mechanism for sediment to be entrained within the flow at low average velocities. A review of the existing state-of-the-art literature has shown there are many variables to consider, i.e., particle density, flow velocity, and turbulence, when assessing the suspended sediment characteristics within flow; this outcome further evidences the complexity of suspended sediment transport modelling
Stochastic Simulation of the Suspended Sediment Deposition in the Channel With Vegetation and Its Relevance to Turbulent Kinetic Energy
No full textYesThe aquatic vegetation patch plays a significant role on sediment net deposition in the vegetated channels. Particularly, the flow is decelerated at the leading edge of a patch that tends to induce vertical updraft, that is, a diverging flow region, in which vegetation greatly affects the pattern of sediment net deposition. This study focuses on the simulation of the sediment net deposition in the whole vegetation patch region through an innovative random displacement model, a Lagrange method, with probability-based boundary conditions, instead of the reflection or sorption boundary at the channel bottom. The probability model of deposition and resuspension is proposed according to the flow field characteristics in the different regions of the vegetation patch. The variation of the sediment deposition and resuspension with the turbulent kinetic energy is analyzed to illustrate the effect of the turbulence induced by vegetation, represented by the dimensionless turbulent kinetic energy (ψ), on the sediment deposition and resuspension. The sediment deposition predicted by the proposed model agrees well with the experimental measurements. Results show that the effect of vegetation on the sediment deposition and resuspension motions begins to prevail when the vegetation-induced ψ is larger than its threshold, ψ *. The threshold of ψ is predicted to be within 6.8-10 according to the simulation results in this study. As the turbulent kinetic energy increases, the deposition probability decreases continuously when ψ > ψ *.National Natural Science Foundation of China (NSFC). Grant Numbers: 52020105006, 11872285; UK Royal Society - International Exchanges Program. Grant Number: IES\R2\181122; Open Funding of State Key Laboratory of Water Resources and Hydropower Engineering Science (WRHES), Wuhan University. Grant Number: 2018HLG0
Blockchain adoption in the maritime supply chain: Examining barriers and salient stakeholders in containerized international trade
No full textYesThis study aimed to investigate the relationships between blockchain adoption barriers and identified the salient stakeholders for blockchain adoption in containerized international trade. The interpretative structural modelling and Cross-Impact Matrix Multiplication Applied to Classification analyses indicated that the most impactful among the eight barriers are lack of support from influential stakeholders, lack of understanding regarding blockchain, and lack of government regulations. The stakeholder mapping analysis demonstrated that the high salient stakeholders among 11 legitimate stakeholders are container lines, ports, beneficial cargo owners, freight forwarders/third party logistics, and customs authorities. The study is original and contributes to theory and practice as it uncovers both impactful barriers and critical stakeholders by adopting a stakeholder theory perspective and offers significant implications to practice, policy, and theory by combining these two analyses
Improving evidence-based practice through preregistration of applied research: barriers and recommendations
Get PDFYesPreregistration is the practice of publicly publishing plans on central components of the research process before access to, or collection, of data. Within the context of the replication crisis, open science practices like preregistration have been pivotal in facilitating greater transparency in research. However, such practices have been applied nearly exclusively to basic academic research, with rare consideration of the relevance to applied and consultancy-based research. This is particularly problematic as such research is typically reported with very low levels of transparency and accountability despite being disseminated as influential grey literature to inform practice. Evidence-based practice is best served by an appreciation of multiple sources of quality evidence, thus the current review considers the potential of preregistration to improve both the accessibility and credibility of applied research towards more rigorous evidence-based practice. The current three-part review outlines, first, the opportunities of preregistration for applied research, and second, three barriers - practical challenges, stakeholder roles, and the suitability of preregistration. Last, this review makes four recommendations to overcome these barriers and maximise the opportunities of preregistration for academics, industry, and the structures they are held within - changes to preregistration templates, new types of templates, education and training, and recognition and structural changes
Ultra-Compact mm-Wave Monolithic IC Doherty Power Amplifier for Mobile Handsets
Get PDFYesThis work develops a novel dynamic load modulation Power Amplifier (PA) circuity that can provide an optimum compromise between linearity and efficiency while covering multiple cellular
frequency bands. Exploiting monolithic microwave integrated circuits (MMIC) technology, a fully integrated 1W Doherty PA architecture is proposed based on 0.1 µm AlGaAs/InGaAs Depletion- Mode (D-Mode) technology provided by the WIN Semiconductors foundry. The proposed wideband DPA
incorporates the harmonic tuning Class-J mode of operation, which aims to engineer the voltage waveform via second harmonic capacitive load termination. Moreover, the applied post-matching technique not only reduces the impedance transformation ratio of the conventional DPA, but also restores its proper load modulation. The simulation results indicate that the monolithic drive load modulation PA at 4 V operation voltage delivers 44% PAE at the maximum output power of 30 dBm at
the 1 dB compression point, and 34% power-added efficiency (PAE) at 6 dB power back-off (PBO). A power gain flatness of around 14 ± 0.5 dB was achieved over the frequency band of 23 GHz to 27 GHz. The compact MMIC load modulation technique developed for the 5G mobile handset occupies the die
area of 3.2.This research was funded by the European Regional Development Fund (FEDER), through COMPETE 2020, POR ALGARVE 2020, Fundação para a Ciência e a Tecnologia (FCT) under i-Five Project (POCI-01-0145-FEDER-030500). This work is also part of the POSITION-II project funded by the ECSEL joint Undertaking under grant number Ecsel-345 7831132-Postitio-II-2017-IA. This work is supported by FCT/MCTES through national funds and when applicable co-funded EU funds under the project UIDB/50008/2020-UIDP/50008/2020. The authors would like to thank the WIN Semiconductors foundry for providing the MMIC GaAs pHEMT PDKs and technical support. This work is supported by the Project TEC2017-88242-C3-2-R- Spanish Ministerio de Ciencia, Innovación e Universidades and EU-FEDER funding
Can handheld POC capillary lactate measurement be used with arterial and venous laboratory testing methods in the identification of sepsis?
No full textNoThe aim of this review was to examine whether the measurement of lactate in capillary blood samples using point-of-care handheld analysers corresponds sufficiently closely with arterial and venous whole-blood samples analysed by hospital central laboratory or blood gas analyser to be used interchangeably.
A systematic search, informed by focused inclusion/exclusion criteria, was performed using multiple databases up to October 2015. A total of 65 articles were considered to have potential relevance and were evaluated in full text, of which ultimately five articles met all inclusion/exclusion criteria, and a final four were selected after data extraction and quality appraisal.
All four studies found a predominantly upward bias in the measurement of lactate in capillary samples tested using a handheld point-of-care device over arterial or venous samples tested by laboratory methods or blood gas analyser. In terms of correlation, there was consensus between the studies that the strength of association between the two methods of measurement was statistically significant. Three studies directly examined the extent of agreement between point-of-care capillary lactate measurements and those of laboratory or blood gas analyser reference determined to ±2 standard deviations; 95% confidence intervals, and report contextually broad limits of agreement, identifying a potential for both over triage and, to a lesser extent, under triage. The findings of the review do not support interchangeable use of handheld fingertip point-of-care lactate measurement with laboratory or blood gas analyser methods in the identification of sepsis
Demountable connections of reinforced concrete structures: Review and future developments
Get PDFYesIn the current practice, at the end of life of a reinforced concrete structure, it is destructively demolished and the demolition waste is landfilled or recycled. This approach is clearly wasteful of energy, creating serious environmental pollution and at high cost. However, design for demountability/deconstruction (DfD) of reinforced concrete structures would facilitate the future reuse of structural elements at the end of their life, potentially achieving a significant reduction in embodied energy of structures as well as giving the clients the benefit of retaining the value of their assets.
In this paper, recent research developments and practical applications of DfD of reinforced concrete structures are reviewed and key technical issues are discussed. The main focus was on connections that should be designed in such a way to allow demounting. The main achievements are outlined, for each type of dry and semi dry connections, along with the aspects that still need to be developed. It is concluded that only semi-dry connections are currently implemented but information available in the literature on dry connections between structural elements is still very scarce. The paper concludes with an outline of some future opportunities and challenges in the application of DfD in concrete construction
Natural organic matter (NOM) and turbidity removal by plant-based coagulants: A review
Get PDFyesNOM deteriorates water quality by forming taste, clarification, colour, and odour problems. It also increases coagulant and chlorine consumption which can initiate disinfection by-products harmful to human health. The coagulation-flocculation (CF) technique is an established method commonly employed to remove NOM in water treatment. Plant-based coagulant products (PCPs) derived from plants like the Moringa oleifera (MO) Strychnos potatorum Linn and Opuntia ficus indica, have been studied and proposed as sustainable alternatives to chemical coagulant, like, aluminium sulphate due to their abundant availability, low cost, low sludge volume and disposal cost, and biodegradability. This review paper provides an overview of the most widely studied plant-based coagulants and discusses their NOM and turbidity removal. It investigates recent analytical tools applied in their characterisation and floc morphological studies. The paper also investigates the effects of operating parameters such as coagulant dose, temperature, and pH, on NOM and turbidity removal. It also reviews up-to-date PCPs biophysical properties and CF mechanism and examines the efficiency of their extraction methods in reducing NOM. Finally, it discusses and suggests ways to overcome commercialisation draw-back caused by nutrient addition
Deep Quantile Regression for Unsupervised Anomaly Detection in Time-Series
Get PDFYesTime-series anomaly detection receives increasing research interest given the growing number of data-rich application domains. Recent additions to anomaly detection methods in research literature include deep neural networks (DNNs: e.g., RNN, CNN, and Autoencoder). The nature and performance of these algorithms in sequence analysis enable them to learn hierarchical discriminative features and time-series temporal nature. However, their performance is affected by usually assuming a Gaussian distribution on the prediction error, which is either ranked, or threshold to label data instances as anomalous or not. An exact parametric distribution is often not directly relevant in many applications though. This will potentially produce faulty decisions from false anomaly predictions due to high variations in data interpretation. The expectations are to produce outputs characterized by a level of confidence. Thus, implementations need the Prediction Interval (PI) that quantify the level of uncertainty associated with the DNN point forecasts, which helps in making better-informed decision and mitigates against false anomaly alerts. An effort has been made in reducing false anomaly alerts through the use of quantile regression for identification of anomalies, but it is limited to the use of quantile interval to identify uncertainties in the data. In this paper, an improve time-series anomaly detection method called deep quantile regression anomaly detection (DQR-AD) is proposed. The proposed method go further to used quantile interval (QI) as anomaly score and compare it with threshold to identify anomalous points in time-series data. The tests run of the proposed method on publicly available anomaly benchmark datasets demonstrate its effective performance over other methods that assumed Gaussian distribution on the prediction or reconstruction cost for detection of anomalies. This shows that our method is potentially less sensitive to data distribution than existing approaches.Petroleum Technology Development Fund (PTDF) PhD Scholarship, Nigeria (Award Number: PTDF/ ED/PHD/IAT/884/16
Effect of Education on Myopia: Evidence from the United Kingdom ROSLA 1972 Reform
Get PDFYesCross-sectional and longitudinal studies have consistently reported an association between education and myopia. However, conventional observational studies are at risk of bias due to confounding by factors such as socioeconomic position and parental educational attainment. The current study aimed to estimate the causal effect of education on refractive error using regression discontinuity analysis.
Methods: Regression discontinuity analysis was applied to assess the influence on refractive error of the raising of the school leaving age (ROSLA) from 15 to 16 years introduced in England and Wales in 1972. For comparison, a conventional ordinary least squares (OLS) analysis was performed. The analysis sample comprised 21,548 UK Biobank participants born in a nine-year interval centered on September 1957, the date of birth of those first affected by ROSLA.
Results: In OLS analysis, the ROSLA 1972 reform was associated with a −0.29 D (95% confidence interval [CI]: −0.36 to −0.21, P < 0.001) more negative refractive error. In other words, the refractive error of the study sample became more negative by −0.29 D during the transition from a minimum school leaving age of 15 to 16 years of age. Regression discontinuity analysis estimated the causal effect of the ROSLA 1972 reform on refractive error as −0.77 D (95% CI: −1.53 to −0.02, P = 0.04).
Conclusions: Additional compulsory schooling due to the ROSLA 1972 reform was associated with a more negative refractive error, providing additional support for a causal relationship between education and myopia.Global Education program of the Russian Federation government (DP) and an NIHR Senior Research Fellowship award SRF-2015-08-005 (CW), The Department for Health through an award made by the NIHR to the Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, London, United Kingdom (grant no. BRC2_009). Additional support was provided by The Special Trustees of Moorfields Eye Hospital, London, United Kingdom (grant no. ST 12 09