Search Results (25)

To study the interference effects of the fuselage/rear-mounted propeller on the aerodynamic and aeroacoustic characteristics at a forward speed of Ma = 0.323, a multi-component flowfield simulation and an aeroacoustic prediction method were employed. Firstly, hybrid grids were adopted in the embedded grid system, and a new boundary identification method was developed to address the overlap problem by adjusting the grid boundary based on entities. The simulations were based on the URANS and FW-H equations. The employed numerical analysis methods were validated through comparisons with experimental data. Then, the aerodynamic and aeroacoustic characteristics of the propeller were analyzed, and the interference of the fuselage with the propeller was discussed in detail. Key findings included the following. Under fuselage interference, the sound pressure level (SPL) of the propeller at those observers near the forward flight direction increased dramatically, by more than 10 dB, especially in the range of two to six times the fundamental frequency. A downward vertical velocity reduced the SPLs beneath the fuselage, while an upward one had the opposite effect. The flat/vertical tails’ deceleration effect caused a thrust surge in the propeller, with most magnitudes around 20%. At different forward speeds, the thrust surge and SPL changes were similar. Full article

To promote the low-carbon energy transition, China is implementing renewable energy (RE) development policies such as renewable portfolio standards (RPSs), carbon emissions trading (CET) and China certified emission reduction (CCER) trading. However, using China’s current CET price to accurately reflect market information is difficult, which is not conducive to guiding low-carbon investment. Additionally, as RE power enters the era of grid parity, more revenues are needed to maintain generator operations. Therefore, in this study, we construct a system dynamics model to explore whether and how market mechanisms can optimize the power generation structure, and sensitivity analyses of CCER policy parameters are carried out to identify the impact and scope for improvement. The results show that (1) the market mechanism, especially the RPS mechanism, adjusts the profits of power generators, eliciting a surge in RE generation and optimizing the power generation structure; (2) CET and CCER prices change in the opposite direction of tradable green certificates (TGCs) and show a significant improvement effect on the on-grid electricity price; (3) successful implementation of the CCER mechanism can effectively energize the CET market. A lower CCER benchmark price, higher CCER offset ratio and CET fines can accelerate the growth of CCER and CET prices. Therefore, the government should promote TGC separation from power trading and rationally design CCER policies by lowering the CCER credit ratio, increasing CET fines, and expanding CCER market capacity to ensure that the guiding role of the market mechanism is better utilized. Full article

The effects of wave and current on floating offshore wind turbines (FOWTs) are usually treated separately without considering their inherent interaction. In this study, the coupling effect of wave and current on the dynamic responses of a semi-submerged FOWT carrying a 5-MW NREL turbine is investigated. A numerical model considering the wave–current interaction is introduced, which accounts for the frequency shifts and surface profile changes for waves traveling over currents. The dynamic structural model of the semi-submerged FOWT is established in ANSYS AQWA, where the aero-servo-structural loadings on tower and turbine were obtained from the FAST platform by using the FAST-to-AQWA coding program. Irregular waves with 1- and 50-year return periods, in conjunction with a uniform current, were adopted to evaluate the coupling interaction effects. Waves traveling on positive and on opposite currents are examined in different cases with waves and currents propagating along the surge or sway direction. Waves consistently propagate along positive surge or sway direction. Waves interacting with positive or opposite currents have dramatically different modifications on the wave spectrum. Differences of up to 22% are recorded by comparing both the main motions and mooring tension when the interaction of waves and currents is considered or not. The coupling interaction between waves and currents has a limited influence on the tower base shear forces and bending moments. It was found that a straightforward superposition approach to evaluate the effect of the waves and the currents may underestimate the dynamic motions and mooring tension of FOWTs. Full article

Increased consumer concern about environmental issues has led to a surge in green advertising, including misleading forms known as greenwashing. Definitions of greenwashing have mostly focused on companies misleading consumers about products, and existing empirical analyses of greenwashing effects have mostly used fabricated ad materials referring to fictitious products. The objective of the present paper is to use ad material from an actual ad campaign to examine joint greenwashing, by an industry organization and a national government, of consumer products and public policies. Using an actual government-subsidized video commercial for ‘Swiss meat’ as an example, the present paper examines greenwashing targeting both consumers and citizens to influence their product choices and policy opinions. Based on an online survey of an age- and gender-representative sample (n = 637), we measured aspects of consumer knowledge that would enable the consumers to put the ad’s message in perspective, perceptions of the ad, and beliefs about Swiss meat production. Furthermore, we used a two-factorial experimental design to examine how the video commercial and objective product information affected policy opinions relative to control treatments. We find that the consumers strongly overestimated the true percentage of Swiss farms that used the environmentally friendly feeding system featured in the ad. Regarding perceptions, 52% of the respondents ‘rather’ or ‘fully’ agreed with the statement ‘the ad conveys a realistic image of Swiss meat production’, and 41% ‘rather’ or ‘fully’ agreed with the statement ‘the ad shows the production of Swiss beef as it is’. Regarding beliefs, 51% of the respondents ‘partly’, ‘rather’, or ‘fully’ agreed that ‘more meat production in Switzerland is good for the environment’. The video commercial did not influence beliefs about Swiss meat but changed policy opinions in the favor of government subsidies for the advertisement of Swiss meat. The information treatment influenced policy opinions in the opposite direction but did not decrease the effect of the misleading ad. Other significant predictors of support for increased meat subsidies included frequent meat consumption, low factual knowledge, and positive product beliefs. The results of the survey indicate that the ad campaign may have unduly influenced perceptions of Swiss meat production and public opinion about agricultural policy. The findings raise concerns about the current self-regulation of the communication industry and joint private and public advertising of Swiss agricultural products and policies. Full article

With the development of renewable energy and the utilization of marine resources, large-scale offshore floating photovoltaics have gradually attracted widespread attention. In order to develop offshore floating photovoltaics and promote sustainable development, it has become necessary to explore the hydrodynamic characteristics of floating photovoltaic units and floating arrays. In this work, based on the viscous flow theory, the Computational Fluid Dynamics (CFD) and the discrete element method (DEM) methods are used to analyze the hydrodynamics of the floating body unit of offshore floating photovoltaics. The influencing factors include mooring length, mooring radius, and floating unit length. In addition, the hydrodynamic performance of the floating body unit and the floating body array under different wave heights and periods is also discussed to explore the influence of environmental loads on the floating body unit and the floating body array. The results indicate that the mooring tension exhibits an opposite trend with the surge and heave motions when the mooring line length and radius are varied. The motion is found to be more pronounced when the floating body unit length is 0.4 times the wavelength. The heave motion of the floating body unit exhibits a strong linear relationship with wave height, increasing by 0.01 m for every 0.015 m increase in wave height. The motion of the floating body units on both sides connected to the mooring lines decreases as the array length increases. Full article

Typhoons, extratropical cyclones, and cold fronts cause strong winds leading to storm surges and waves in the Bohai Sea. A wave–flow coupled numerical model is established for storm events observed in 2022 caused by three weather systems, to investigate how storm waves are modulated by wave–tide–surge interaction (WTSI). Wave response is basically controlled by water level change in coastal areas, where bottom friction or breaking dominates the energy dissipation, and determined by the current field in deep water by altering whitecapping. Wave height increases/decreases are induced by positive/negative water level or obtuse/acute wave–current interaction angle, leading to six types of field patterns for significant wave height (Hs) responses. For the three storm events, Hs basically changed within ±5% in central deep water, while the maximum increase/decrease reached 160%/−60% in the coastal area of Laizhou Bay/Liaodong Bay. Based on maximum Hs and its occurrence time, WTSI modulation is manifested as the superposition effect of wave–tide and wave–surge interactions in both space and time scales, and occurrence time depends more on tide than surge for all three storms. The enhancement/abatement of WTSI modulation happens for consistent/opposite changing trends of wave–tide and wave–surge interaction, with the ultimate result showing the side with a higher effect. Full article

In light of the rapid Arctic warming and continuous reduction in Arctic Sea ice, the complex two-way Arctic–midlatitudes connection has become a focal point in recent climate research. In this paper, we review the current understanding of the interactive influence between midlatitude atmospheric variability and Arctic Sea ice or thermal conditions on interannual timescales. As sea ice diminishes, in contrast to the Arctic warming (cooling) in boreal winter (summer), Eurasia and North America have experienced anomalously cold (warm) conditions and record snowfall (rainfall), forming an opposite oscillation between the Arctic and midlatitudes. Both statistical analyses and modeling studies have demonstrated the significant impacts of autumn–winter Arctic variations on winter midlatitude cooling, cold surges, and snowfall, as well as the potential contributions of spring–summer Arctic variations to midlatitude warming, heatwaves and rainfall, particularly focusing on the role of distinct regional sea ice. The possible physical processes can be categorized into tropospheric and stratospheric pathways, with the former encompassing the swirling jet stream, horizontally propagated Rossby waves, and transient eddy–mean flow interaction, and the latter manifested as anomalous vertical propagation of quasi-stationary planetary waves and associated downward control of stratospheric anomalies. In turn, atmospheric prevailing patterns in the midlatitudes also contribute to Arctic Sea ice or thermal condition anomalies by meridional energy transport. The Arctic–midlatitudes connection fluctuates over time and is influenced by multiple factors (e.g., continuous melting of climatological sea ice, different locations and magnitudes of sea ice anomalies, internal variability, and other external forcings), undoubtedly increasing the difficulty of mechanism studies and the uncertainty surrounding predictions of midlatitude weather and climate. In conclusion, we provide a succinct summary and offer suggestions for future research. Full article

Confronted with China’s burgeoning population and finite arable land resources, the enhancement of sustainable arable land efficiency is of paramount importance. This study, grounded in the United Nations Sustainable Development Goals (SDGs), introduces a robust framework for assessing sustainable arable land use. Utilizing the Sustainable Utilization of Arable Land (SUA) indicator system, the DGA–Super-SBM model, the Malmquist–Luenberger production index, and the TO–Fisher–OSM algorithm, we evaluated the efficiency of sustainable utilization of arable land (ESUA) in 52 prefecture-level cities within China’s major grain-producing regions of the Yellow and Huaihai Seas. We analyzed the cropland utilization patterns from 2010 to 2020, examining the influence of these patterns on sustainable utilization efficiency. Our findings indicate that between 2010 and 2020, the arable land usage in these regions exhibited minimal transformation, primarily shifting towards construction land and conversely from grassland and water systems. Notably, the ESUA of arable land demonstrated an upward trend, characterized by pronounced spatial clustering, enduring high efficiency in the northern regions, and a significant surge in the southern sectors. The declining ESUA (D-ESUA) trend was general but increased in half of the cities. The change in the center of gravity of ESUA correlated with the north–south movement of the proportion of cultivated land area, the turn-in rate, and the turn-out rate, yet moved in the opposite direction to that of cultivated land density and yield per unit area. Variables such as the replanting index, cropland density, yield per unit area, and cropland turn-in rate significantly affected ESUA. These findings offer a scientific basis and decision-making support for optimizing the utilization pattern of arable land and achieving a rational allocation of arable land resources. Full article

The COVID-19 pandemic has led to a surge in online studio education, which has presented a significant challenge to traditional design studio teaching methods that rely on face-to-face interactions between instructors and students. It is contended that online studio education enhances the accessibility of design studio pedagogy, making it possible for students to learn from anywhere in the world. However, it also challenges the development of tactile skills, which are crucial in design education. Additionally, online studio education can render certain aspects of traditional design studio pedagogy obsolete, while bringing back elements of design history and theory that may have been overlooked in traditional studio teaching. It can also be argued that online studio education has the potential to reverse the traditional power dynamics between instructors and students, resulting in more democratic and collaborative forms of learning that can empower students. As the literature on the effects of online studio education is growing, there is a need to understand how the shift from the material space and its affordances to an online environment affects the core components of an architectural design studio. To understand the effects of this new medium, this research employed Marshall McLuhan’s tetradic approach, a hermeneutic tool to perform a critical interpretation of any medium by examining four simultaneous effects: how it enhances a human sense, what it makes obsolete, what forgotten aspect it retrieves, and how it flips into its opposite at its extremes. A literature review was conducted to analyze the effects of online studios from a tetradic framework and identify the major discussions of the impact of online studio education. The methodology involves a two-part literature review. This study specifically focused on peer-reviewed, empirical research published after 2020, and the authors used search terms related to online architectural studios during the pandemic. The process identified 176 records of peer-reviewed empirical studies for further analysis and 20 papers were read and included in the review, defining repeating topics/themes and organized under four categories pertaining to the founding archetypes of an architectural design studio: (a) setting and communication, (b) actors, (c) outputs, and (d) dynamics. This process was followed by organizing the findings and interpreting them within the tetradic framework to develop a comprehensive understanding of the consequences of the online design studio. Overall, this research aims to provide a detailed and nuanced analysis of the impact of online studio education on design studio pedagogy, conceptualizing McLuhan’s tetrad as a basis for the analysis, and therefore aiming to enrich our understanding of the post-COVID-19 era of learning architecture by examining the dramatic change in the medium and its effects. Full article

Under the premise of using the solid-phase method to pre-sinter Bi₂O₃ and Sb₂O₃ into BiSbO₄ as a substitute for equal amounts of Bi₂O₃ and Sb₂O₃ in the formula, the effects of co-doping with In(NO₃)₃, Al(NO₃)₃, and Y(NO₃)₃ on the microstructure and electrical properties of ZnO varistors were studied. The experimental results show that with an increase in In³⁺-doped molar concentration, the leakage current of the ZnO varistor shows a rapid decrease and then a slow increase trend. However, the nonlinear coefficient is the opposite of it. With the combined effect of the rare earth element Y³⁺, the average grain size is significantly reduced, which leads to an increase in the voltage gradient. At the same time, a certain amount of doped In³⁺ and Al³⁺ is dissolved into the grains, resulting in a decrease in grain resistance and thus a low level of residual voltage. The varistor with 0.6 mol% In³⁺, 0.1 mol% Al³⁺, and 0.9 mol% Y³⁺ doping ratios exhibits excellent overall performance. The nonlinear coefficient is 62.2, with the leakage current being 1.46 µA/cm² and the voltage gradient being 558 V/mm, and the residual voltage ratio is 1.73. The prepared co-doped ZnO varistors will provide better protection for metal oxide surge arresters. Full article

In recent days, there has been a noticeable surge in demand for high-quality rice. However, the influences of salinity on the quality and starch properties of high-quality rice remain unclear. Three high-quality rice cultivars (Nanjing 9108, Nanjing 5055, and Nanjing 46) were studied to investigate the responses of grain quality to salt stress. There were three treatments, including a control zero salt level (0 g·kg⁻¹, CK), and two salt levels of 0.1 g·kg⁻¹ (0.1% salt stress, T1) and 0.2 g·kg⁻¹ (0.2% salt stress, T2). The study involved the assessment of the appearance, milling, cooking, and eating qualities of rice. We also conducted an analysis of pasting properties, an evaluation of starch thermal properties, and an examination of the fine structure of amylopectin. The findings suggest that as the level of salt stress increases, the yield of rice gradually declines, which is primarily due to a significant reduction in the total spikelet number and the ratio of filled grains. Compared with CK treatment, the appearance and milling quality of rice were significantly improved within the T1 treatment. In addition, the protein concentration and amylose concentration were significantly decreased, the gel consistency was significantly increased, and the cooking and eating qualities were improved. In terms of starch properties, the peak viscosity, breakdown value, infrared ratio (1022/995), and short-chain-length amylopectin ratio increased significantly, while the setback value, pasting temperature, gelatinization enthalpy, relative crystallinity, and infrared ratio (1045/1022) decreased significantly. When comparing T2 with CK, the appearance quality and cooking and eating quality had deteriorated, and the milling quality was improved. The changes in the structural and physicochemical properties of starch were opposite to those in the comparison between the T1 treatment and the CK group. Accordingly, we propose that moderate salt stress has the potential to enhance rice quality, even though there may be a slight decrease in yield. This indicates that it is feasible to cultivate high-quality rice in saline–alkali beach areas. Full article

In recent years, multi-bucket foundations have been studied and gradually adopted in engineering practices as a novel foundation for offshore wind turbines within a range of water depth of 30 to 50 m. This study investigated the motion characteristics of air-floating tripod bucket foundation (AFTBF) through a series of experiments during free air-floating. The experimental results show that the surge force appears to be the most important factor influencing pitch moment and motion, whether it is a change in water depth or a draft for AFTBF. The maximum amplitudes of surge acceleration and pitch angle show a trend of increasing with narrower spacing and decreasing with wider spacing, while the heave acceleration shows an opposite trend. The added mass and damping of heave motion for AFTBF increase with shallower water due to the increasing pressure difference between the inside and bottom of bucket foundation. The shallower the water depth and the larger the draft, the longer the resonance period of heave. Full article

Wide tensions regarding the organization of nation-state power have been triggered over the last years in the UK and Spain. By contrast, in the UK, (i) the plebiscite on Scottish Independence has been characterized since 2014 so far by a regular hegemony of the SNP in Scotland, and (ii) more recently, distinct resilient responses to tackle COVID-19 have dramatically shifted perceptions about the potential constitutional arrangements in Wales partially opposing a state-centric vision of the UK. By contrast, the role played by the constitutionally illegal but socially constitutive referendum in Catalonia on 1 October 2017, remarkably provoked the re-emergence of the Spanish far-right narrative through the surge of the new political party called Vox. In both cases, the urban in Glasgow, Cardiff, and Barcelona has been shaping various oppositions to state-centric agendas, and such oppositions have shaped elections in the UK and Spain. This article sheds light on the distinct, emerging, and emancipatory urban citizenship regimes in Catalonia, Scotland, and Wales, particularly illustrating the roles that Barcelona, Glasgow, and Cardiff, respectively, are playing in articulating a counter-reaction by rescaling a state-centric vision. This article employs past elections’ evidence to illustrate such regimes amid postpandemic times in datafied states. Full article

Motivated by increased agricultural commodity price volatility and surges during the past decade, we investigated whether financial speculation is to blame. The aim of this paper is to build on prior research about to what extent and in which ways financial speculation undermines agricultural commodity prices. In our analysis, we utilized the daily returns on milling wheat, corn, and soybean futures from the Euronext Commodities Paris market (MATIF) as well as the short-term speculation index. To quantify this impact, we apply Granger noncausality tests as well as the GARCH (generalized autoregressive conditional heteroskedasticity) technique. We also propose a model using seasonal dummy variables to examine whether financial speculation has a greater impact on price volatility during more volatile months. According to our results, financial speculation, as an external factor, in most cases has no effect or reduces the volatility of the underlying futures prices. The opposite is observed in the corn market, where volatility has risen in the post-2020 period and has been pushed up even more by speculation in April. However, since the influence on other commodities is limited or nonexistent, more emphasis should be focused on speculation in the European corn futures market or its interdependence with energy markets. Full article

Metal contaminants can distort the surface electric field of the tri-post epoxy insulator and cause serious surface charge accumulation, significantly reducing the insulation performance of the insulator under the superimposed DC and lightning impulse voltage. In this paper, an experimental platform for charge accumulation and surface flashover of tri-post epoxy insulators under the superimposed DC and lightning impulse voltage was built, by surface point measurement and charge inversion calculation, the surface charge distribution characteristics of tri-post insulators with attached particles was experimentally explored and the influence law of attached metal particles on the charge accumulation was discussed. The results show that metal particles can cause a surge in the surface charge density of the tri-post epoxy insulator, forming bipolar charge spots whose polarity is opposite to that of the adjacent electrodes. The adsorbed metal dust can cause the polarity reversal of adjacent surface charges, forming a large-area unipolar charge spot. Moreover, the flashover voltage of a tri-post insulator under DC superimposed lightning impulse voltage with a clean surface and attached metal particle was measured, and the synergistic induction mechanism of charge spot accumulation and metal particle discharge on the flashover along the face of the tri-post insulator is thereby revealed. Compared with the clean insulators, the surface flashover voltages of tri-post epoxy insulators with metal contaminants adhered decrease under the superimposed voltages of different polarities, but the decline amplitude is greater under the heteropolar composite voltage. When adhered to the middle of the insulator leg, the distribution range of bipolar charge spots is the widest, and the surface flashover voltage decreases sharply, which can drop by 32% compared with the absence of particles. In addition, when the metal dust adsorbed by the tri-post epoxy insulator has a wide distribution range, the impact of metal dust on the flashover voltage is greater than that of the attached metal particles, and its hazard cannot be ignored. The research results can provide a reference for the insulation test method and optimal design of the DC tri-post epoxy insulator. Full article