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Influence of pile length on dynamic performance of monopile wind turbine
No full textThe influence of pile configuration on safety of wind turbines has been attracting large amounts of attention recently. On the one side, the cost for the foundation accounts for 35 % of the total cost of monopile supported wind turbines (MWTs). On the other side, the working environment of wind turbines brings complex loads to monopiles. In this paper, a series of wind tunnel tests are performed with scaled model under different ground and operation conditions. The test results show that pile length factor (PLF) affect nacelle displacement and maximum pile moment negatively. Top acceleration confirmed a stationary random vibration. The natural frequency of model MWTs increases 11.6 % (dense ground) and 10.1 % (loose ground) when PLF increase from 0.264 to 0.362. While damping ratio decreases 1.447 % (dense ground) and 1.493 % (loose ground). These test results can be up scaled to estimate prototype's dynamic properties. According to test results, some numerical fitting surfaces including d-Ω-PLF, f-Ω-PLF and ξ-Ω-PLF have been established to check unfavorable working conditions, which can be used to guide the design of piles to support MWTs
Quantitative surface characterisation and stress concentration of additively manufactured NiTi lattice struts
No full textWith the advancement of metal additive manufacturing (AM), lattice structures become a promising solution to situations that require lightweight design and yet maintain adequate mechanical strength. Limited by the quality of feedstock materials, the layer-wise process characteristic and the dynamic nature of thermal environment, lattice structures made by AM often suffer from process-induced imperfections such as poor surface finish and notable geometric deviation. In this study, systematic quantitative characterisation methods are developed to address surface quality and geometric discrepancy of NiTi lattice struts made by laser powder bed fusion (LPBF), with a special focus on fatigue-related features such as stress concentration factors. The results show that for the examined strut diameters and inclination angles, the strut diameter plays a significant role in geometry inaccuracy and the inclination angle has a greater effect on surface texture and stress concentration factor distribution on the surface. Lattice struts with diameters greater than 0.7 mm and inclination angles over 40° with respect to the platform exhibit superior manufacturing quality among all configurations of the struts. The proposed approach not only opens a new avenue to evaluate μ-CT data in a more quantitative way but also offers opportunities to develop guidelines for lattice structure design
Effects of hotels’ green practices on consumer citizenship behavior
No full textThis study investigates the influence of hotels’ green practices on consumer citizenship behavior and whether this relationship is mediated by perceived value and psychological safety utilizing the cognitive behavioral theory. This study also examines the moderating effects of social influence. Results show that green hotel practices are positively related to consumer citizenship behavior. Perceived value and psychological safety positively mediate this relationship. Furthermore, social influence positively moderates the relationship between green hotel practices and perceived value and between green hotel practices and psychological safety. These findings provide both theoretical and practical implications for researchers and hotel managers in planning and implementing green practices to influence consumers’ perceptions, feelings, and behaviors towards hospitality businesses
Numerical simulation of safety injection and natural circulation in two containers by smoothed particle hydrodynamics on the effects of filling levels and thermal diffusivities
No full textNatural circulation is an important process in reactor thermal-hydraulics study. This process is simulated by Smoothed particle hydrodynamics method for a modeled system of circulation. A new kernel function of (−1, 5) power components has been proposed here and validated by the dam-break case. The modeled circulation system is composed of two containers of different heights. Three filling levels (Case A) and four thermal diffusivities (Case B) have been utilized to analyze their effects. Six vortex-criteria have been utilized to visualize the representative vortical motion of fluids inside the containers. Circulations of velocity and velocity–temperature, heat transfer amount, mean temperature and mean material derivative have been defined here to quantify the feature of natural circulations for the two cases. The results show that the filling levels affect mainly the process of setup, rather than the steady level of natural circulation. A high filling level has a considerable larger amount of heat transfer between the hot and cool fluids. The thermal diffusivity does not affect the process of the circulation level, whereas it has great effects on the mean as well material derivative of the temperature of fluids. For example, comparing the mean temperature of the fluid at the thermal diffusivity α = 0.02 to that at α = 2.79 (in Case B at t=600 s), the mean temperature of cool fluids is about 15 °C lower at α=0.02 than that at α=2.79, whereas the mean temperature of hot fluids is about 7 °C higher at α=0.02 than that at α=2.79. In addition, the difference in the initial temperature of fluids and the difference in heights between two containers affect the natural circulation levels
Influence of laser parameters on the microstructures and surface properties in laser surface modification of biomedical magnesium alloys
No full textBiodegradable implants from magnesium (Mg) alloys have emerged in the biomedical field especially in the orthopedic and cardiovascular stent applications owing to their low density, high specific strength, excellent machinability, good biocompatibility, and biodegradability. The primary shortcoming of Mg-based implants is their low corrosion resistance in the physiological environment, which results in premature mechanical integrity loss before adequate healing and the production of excessive hydrogen gas, which is harmful to the body tissues and negatively affects the biocompatibility of the implant. Laser surface modification has recently received attention because it can improve the surface properties such as surface chemistry, roughness, topography, corrosion resistance, wear resistance, hydrophilicity, and thus cell response to the surface of the material. The composition and microstructures including textures and phases of laser-treated surfaces depend largely on the laser processing parameters (input laser power, laser scan velocity, frequency, pulse duration, pressure, gas circulation, working time, spot size, beam focal position, and laser track overlap) and the thermophysical properties of the substrate (solubility, melting point, and boiling point). This review investigates the impacts of various laser surface modification techniques including laser surface melting, laser surface alloying, laser cladding, laser surface texturing, and laser shock peening, and highlights their significance in improving the surface properties of biodegradable Mg alloys for implant applications. Additionally, we explore how different laser process parameters affect its composition, microstructure, and surface properties in each laser surface modification technique
Phase-Controlled Tin Selenide Photodetectors for Visible Blind to Near-Infrared Optical Radiation
No full textLayered tin selenides have gained tremendous interest due to their distinct tunable semiconducting properties, narrow band gap, low cost, and feasibility for large-scale production. However, the phase controllability of SnSe and SnSe2 is a major challenge for device applications, which should be addressed to ensure repeatability of crystallographic phase, morphology, defects, etc. We have synthesized highly crystalline and phase-controlled (mono, di, mix) tin selenide films using a low-pressure chemical vapor deposition technique by coupling the precursor and substrate temperatures. The optoelectronic behavior of the constructed metal-semiconductor-metal (MSM) tin selenide-based devices responds to the wide spectral range from visible blind (UVB) to near-infrared (NIR). The designed SnSe2-based photodetector has a high optical response to visible light (532 nm) with responsivity, noise equivalent power, and external quantum efficiency of 1260 mA W-1, 8.27 × 10-12 W Hz-1/2, and 295%, respectively. However, the SnSe-based photodetector exhibits a high response for infrared wavelength (1064 nm) with responsivity, external quantum efficiency, and noise equivalent power of 3320 mA W-1, 388%, and 2.88 × 10-12 W Hz-1/2, respectively. The SnSe-based photodetector outperforms the SnSe2 and SnSemix (mixed phase)-based devices in the optical wavelength range from UVB to NIR. A thorough analysis of a phase-controlled tin selenide photodetector with broad optical detecting capability indicates its adaptability to various industrial and technological domains
Acknowledging Identity and Intersectionality—A Transformative Framework for Design Education Futures
No full textDesign education in Australia is still largely dominated by Westphalian perspectives, values, histories and ways of learning. The focus on Euro-western aesthetics, technologies, timelines and processes marginalises other identities, cultures and places. This signals to students that they should internalise, value and master dominant narratives, knowledges and ways of designing. Responding to this legacy, this article details the development of an intersectional and transformative framework to guide pedagogy for design education futures. Drawing from intersectional, student-centred and transformative learning theories, we argue that students can develop self-awareness and critical evaluation skills through understanding and designing within their own histories and cultures. In applying our framework, we reflect on how we developed a communication design history curriculum that centres on previously marginalised designers and prioritises pluralistic work that comes out of diverse cosmologies, perspectives and points of view. Early results demonstrate that offering spaces for students to connect design to their own intersectional identities increases self-reflection and belonging, while engaging students to contribute new knowledges and perspectives to design history than we have had in the past. We hope this framework contributes to design education moving towards and respecting expanded ways of thinking, seeing and teaching design
Challenges and lessons of implementing strategic environmental assessment in a critically endangered ecosystem
No full textStrategic environmental assessment (SEA) can help to ensure that development across a landscape is planned and implemented with minimum environmental and biodiversity impacts. Despite its growing prevalence, few studies have investigated the implementation of biodiversity conservation interventions associated with SEA. Here, we examine an Australian SEA case study, the Melbourne Strategic Assessment, which set out to assess the impacts of Melbourne’s urban growth boundary expansion on threatened species and ecosystems. Using stakeholder interviews and document analysis, we evaluate the implementation of biodiversity conservation interventions under the SEA. We find that key interventions are yet to be fully implemented, including establishing a 15,000-hectare reserve to offset impacts on critically endangered grasslands. We identify systematic and pervasive failures, including questionable funding and enforcement arrangements, and highlight critical improvements needed. Given the growing use of SEA worldwide, urgent action is required to provide confidence in the ability of SEA to deliver biodiversity conservation objectives
Navigating the crisis: Fuel price caps in the Australian national wholesale electricity market
No full textFuel price caps are one of the potential regulatory tools for controlling wholesale electricity prices when fuel prices are volatile. In this paper, we introduce a theoretical model to study the effects of such caps on firms’ bidding behaviour and clearing prices in spot market auctions. We then use data from the Australian National Electricity Market (NEM), which recently implemented such caps, to empirically test and compare their effectiveness in three different states. Our theoretical findings suggest that fuel price caps can be binding, especially when electricity demand is lower and competition among generators is higher. When demand is high, alternative policy tools, such as market price caps, may be more effective in controlling auction prices. Our empirical analysis employs various techniques, such as Generalized Additive Models (GAM) and machine learning algorithms, to test the effectiveness of price caps in the NEM. We find mixed results regarding the effectiveness of fuel price caps in different states. Specifically, fuel price caps reduced wholesale electricity prices in Queensland and New South Wales, while they were not effective in controlling wholesale prices in Victoria
Exploring Metabolic and Gut Microbiome Responses to Paraquat Administration in Male Wistar Rats: Implications for Oxidative Stress
No full textIn this study, we examined the metabolic and gut microbiome responses to paraquat (PQ) in male Wistar rats, focusing on oxidative stress effects. Rats received a single intraperitoneal injection of PQ at 15 and 30 mg/kg, and various oxidative stress parameters (i.e., MDA, SOD, ROS, 8-isoprostanes) were assessed after three days. To explore the omic profile, GC-qTOF and UHPLC-qTOF were performed to assess the plasma metabolome; 1H-NMR was used to assess the urine metabolome; and shotgun metagenomics sequencing was performed to study the gut microbiome. Our results revealed reductions in body weight and tissue changes, particularly in the liver, were observed, suggesting a systemic effect of PQ. Elevated lipid peroxidation and reactive oxygen species levels in the liver and plasma indicated the induction of oxidative stress. Metabolic profiling revealed changes in the tricarboxylic acid cycle, accumulation of ketone body, and altered levels of key metabolites, such as 3-hydroxybutyric acid and serine, suggesting intricate links between energy metabolism and redox reactions. Plasma metabolomic analysis revealed alterations in mitochondrial metabolism, nicotinamide metabolism, and tryptophan degradation. The gut microbiome showed shifts, with higher PQ doses influencing microbial populations (e.g., Escherichia coli and Akkermansia muciniphila) and metagenomic functions (pyruvate metabolism, fermentation, nucleotide and amino acid biosynthesis). Overall, this study provides comprehensive insights into the complex interplay between PQ exposure, metabolic responses, and gut microbiome dynamics. These findings enhance our understanding of the mechanisms behind oxidative stress-induced metabolic alterations and underscore the connections between xenobiotic exposure, gut microbiota, and host metabolism