•New Zealand is aimed to achieving 100% renewable energy production by 2035.•New Zealand is dedicated to achieve 0% CO2 emissions by 2050.•Richful wind energy in New Zeland has great potential to be ...utilized.•Besides storage, wind energy faces other challenges.•Distributed small-scale wind turbines are attractive in New Zealand.
The restructuring of the energy industry is imperative, as New Zealand strives to reduce greenhouse gas emissions. New Zealand has abundant renewable energy resources, and about 85% of current electricity generation is from renewable energy sources. However, in recent years, it appears that a considerable fraction of wind energy has been underutilized. This article reviews the history, current status, and future trends of wind energy development in New Zealand. The main challenges to the current development of wind energy are summarized compared to other countries. The main challenges come from the bi-cultural influence, environmental influence, and economic and social influence due to the variable nature of wind power, it is critical to store and operate power safely and reliably during peak power generation periods. This article compares seven mainstream wind energy storage technologies and analyzes the best solution for wind energy storage in New Zealand. This article analyzes the feasibility of using small-scale household (standard power rating range from 0.004 to 16 kW) wind turbines in New Zealand cities regarding their construction and operation process. The life cycle and the maximum capacity coefficient of such small-scale wind turbines are overviewed via three case studies and later compared with large commercial wind turbines (standard power rating ranges from 1 to 3 MW) in power generation capacity. It has been found that small-scale household wind turbines have notable power generation potential and economic benefits in the long term.
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This study aims to investigate whether the machine learning algorithms could provide an optimal early mortality prediction method compared with other scoring systems for patients with cerebral ...hemorrhage in intensive care units in clinical practice.
Between 2008 and 2012, from Intensive Care III (MIMIC-III) database, all cerebral hemorrhage patients monitored with the MetaVision system and admitted to intensive care units were enrolled in this study. The calibration, discrimination, and risk classification of predicted hospital mortality based on machine learning algorithms were assessed. The primary outcome was hospital mortality. Model performance was assessed with accuracy and receiver operating characteristic curve analysis.
Of 760 cerebral hemorrhage patients enrolled from MIMIC database mean age, 68.2 years (SD, ±15.5), 383 (50.4%) patients died in hospital, and 377 (49.6%) patients survived. The area under the receiver operating characteristic curve (AUC) of six machine learning algorithms was 0.600 (nearest neighbors), 0.617 (decision tree), 0.655 (neural net), 0.671(AdaBoost), 0.819 (random forest), and 0.725 (gcForest). The AUC was 0.423 for Acute Physiology and Chronic Health Evaluation II score. The random forest had the highest specificity and accuracy, as well as the greatest AUC, showing the best ability to predict in-hospital mortality.
Compared with conventional scoring system and the other five machine learning algorithms in this study, random forest algorithm had better performance in predicting in-hospital mortality for cerebral hemorrhage patients in intensive care units, and thus further research should be conducted on random forest algorithm.
Ice accretion is inevitable on fix-wing UAVs (unmanned aerial vehicles) when they are applied to surveillance and mapping over colder climates and arctic regions. Subsequent aerodynamic profile ...changes have caused the current interest in the better prediction of the effect of icing shapes/sizes/distribution patterns on the aerodynamic performances of an aircraft. This study employs a numerical model which investigates the RG-15 aerofoil’s response to various icing scenarios at a Reynolds number of Re=2×105. Under icing conditions, compared to a clean aerofoil, a reduction in the lift coefficient and an increase in the drag coefficient are observed. Lower temperatures and reduced liquid water content lead to a decrease in the maximum thickness of ice accretion on the RG-15 aerofoil. Particularly noteworthy is the 10.85% reduction in the lift coefficient at a 10° angle of attack, which is in the icing condition at −10 °C with a mean volume diameter of 15 μm. Power consumption increases in the range of 0.46% to 26.5% under various icing conditions, showing synchronization with the rise in drag coefficient. This study underscores the need for future research to investigate various cloud conditions comprehensively and deeply in the context of aerofoil icing.
This study aims to examine the effects of early rehabilitation on functional outcomes in patients with acute ischemic stroke treated with endovascular treatment (EVT).
Eligible patients with large ...vessel occlusion stroke treated with EVT, who received early rehabilitation or standard care treatment during hospitalization, were enrolled in a multicenter registration, prospective observational study, a registration study for Critical Care of Acute Ischemic Stroke After Recanalization. Early rehabilitation was defined as rehabilitation interventions initiated within 1 week after acute stroke. The primary outcome was the favorable functional outcome (defined as modified Rankin Scale scores of 0 to 2) at 90 days. Independent association between early rehabilitation and the primary outcome was investigated using multivariable logistic regression in the entire sample and in subgroups.
A total of 1,126 patients (enrolled from July 2018 to May 2019) were included in the analyses, 273 (24.2%) in the early rehabilitation group and 853 (75.8%) in the standard care group. There was no significant difference in favorable functional outcomes at 90 days between the two groups (45.4 vs. 42.6%,
= 0.41). Patients in the early rehabilitation group had a lower death rate within 90 days compared with the standard care group (6.2 vs. 20.5%,
< 0.01). The multivariable logistic regression analyses showed that the early rehabilitation was not significantly associated with the favorable functional outcome at 90 days (adjusted odds ratio, 1.01 95% CI, 0.70-1.47;
= 0.95). There was no significant difference between subgroups in the favorable functional outcome at 90 days. No significant interaction was found between subgroups.
Patients with stroke receiving early rehabilitation had a lower death rate. However, these clinically meaningful effects of early rehabilitation did not show on functional outcome at 90 days in patients with large vessel occlusion stroke treated with EVT.
URL: http://www.chictr.org.cn; Unique identifier: ChiCTR1900022154.
Abstract
High-dimensional datasets on cultural characters contribute to uncovering insights about factors that influence cultural evolution. Because cultural variation in part reflects descent ...processes with a hierarchical structure – including the descent of populations and vertical transmission of cultural traits – methods designed for hierarchically structured data have potential to find applications in the analysis of cultural variation. We adapt a network-based hierarchical clustering method for use in analysing cultural variation. Given a set of entities, the method constructs a similarity network, hierarchically depicting community structure among them. We illustrate the approach using four datasets: pronunciation variation in the US mid-Atlantic region, folklore variation in worldwide cultures, phonemic variation across worldwide languages and temporal variation in first names in the US. In these examples, the method provides insights into processes that affect cultural variation, uncovering geographic and other influences on observed patterns and cultural characters that make important contributions to them.
BackgroundIdentification of futile recanalisation following endovascular therapy (EVT) in patients with acute ischaemic stroke is both crucial and challenging. Here, we present a novel risk ...stratification system based on hybrid machine learning method for predicting futile recanalisation.MethodsHybrid machine learning models were developed to address six clinical scenarios within the EVT and perioperative management workflow. These models were trained on a prospective database using hybrid feature selection technique to predict futile recanalisation following EVT. The optimal model was validated and compared with existing models and scoring systems in a multicentre prospective cohort to develop a hybrid machine learning-based risk stratification system for futile recanalisation prediction.ResultsUsing a hybrid feature selection approach, we trained and tested multiple classifiers on two independent patient cohorts (n=1122) to develop a hybrid machine learning-based prediction model. The model demonstrated superior discriminative ability compared with other models and scoring systems (area under the curve=0.80, 95% CI 0.73 to 0.87) and was transformed into a web application (RESCUE-FR Index) that provides a risk stratification system for individual prediction (accessible online at fr-index.biomind.cn/RESCUE-FR/).ConclusionsThe proposed hybrid machine learning approach could be used as an individualised risk prediction model to facilitate adherence to clinical practice guidelines and shared decision-making for optimal candidate selection and prognosis assessment in patients undergoing EVT.
This paper examines the effects of applying three Savonius wind turbines with different mounting positions, including lateral spacing, on power coefficients by conducting high-fidelity ...three-dimensional numerical simulations, i.e., based on the Reynolds-Averaged Navier-Stokes (RANS) method. The first validation case of the single Savonius wind turbine located on the fixed step height, and a flat surface is found to be in good agreement with that reported in the literature. Then the model is expanded to study the performances of three laterally aligned Savonius wind turbines by placing them above a flat surface and a forward facing step. When the three laterally placed turbines are on a flat surface, an increase of approximately 5% of the maximum mean power coefficient is observed compared to that of a single turbine. Next, the effect of implementing the three turbines at different positions on a fixed step is investigated, where the maximum mean power coefficient improvement for the three turbines can be as high as 230%. Finally, the effect of the lateral spacing distance between the two adjacent turbines is examined. It has been shown that there is an optimal spacing if the maximum mean power coefficient is concerned.
•Savonius wind turbine is numerically investigated by the three-dimensional aerodynamics simulations.•Installation of such a turbine on a step significantly increases its aerodynamics power coefficient.•Laterally aligned turbines offer further power coefficient gains over an isolated turbine.•Arrayed turbines have an optimal spacing considering the maximum mean power coefficient.
A better prediction of key aerodynamic parameters of a propeller is necessary to improve the performances of unmanned aerial vehicles (UAVs) in different operating environments. In this work, we ...conduct a systematic investigation on an APC 1045 multi-rotor propeller to analyze its aerodynamic performances with wind tunnel tests, blade element momentum theory (BEMT) and 3D computational fluid dynamics (CFD). The theoretical BEMT model provides accurate and reliable estimation at the advance ratios ≤0.567, whereas the method begins to stall at advance ratios ≥0.661. Conversely, the results obtained from CFD simulations agree well with the experiments at all advance ratios, with the differences in thrust- and power coefficients around 5% and 4%, respectively. The present work compares the aerodynamic parameters while varying the freestream velocity to investigate the limitations and advantages of the use of the aforementioned three different methods. Given the limitation of the BEMT, it is found to be reliable enough to estimate the aerodynamic parameters of a small-scaled fixed-pitch propeller. In addition, a more comprehensive investigation of the BEMT shows that increasing advance ratio decreases the lifting portion of the propeller blade, i.e. incurring more losses associated with the hub and tip.
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