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The floating offshore wind turbine provides a feasible solution for the development of renewable ocean energy. However, the sizeable rotor diameter of the wind turbine results in large wind heeling moments and pitch amplitude. It will increase the structural loads and cause safety problems. Additionally, the contradictory nature between the stability and the sea-keeping of the floating structure requires that the more flexible method should be adopted to reduce the motion response of the floating offshore wind turbine. Therefore, an innovative concept of a multibody anti-pitching semi-submersible floating offshore wind turbine, named the MBAPSF, is proposed in this paper. The MBAPSF consists of a 5 MW braceless semi-submersible wind turbine and three wave energy converters. The multibody coupled numerical model is established by using an F2A tool, and the dynamic performance of the MBAPSF is compared with that of the traditional semi-submersible wind turbine named the TSSF. The results show that the innovative concept proposed in this paper can reduce pitch motion up to approximately 27% under different load cases, and the maximum bending moment and shearing force at the tower base are also reduced by more than 10%. Meanwhile, WECs are beneficial for increases in the total power generation capacity. [ABSTRACT FROM AUTHOR]

"Advances in Offshore Wind" is a document that discusses the progress and challenges of offshore wind power. It highlights the advantages of offshore wind power, such as higher wind speeds and conservation of land resources, and notes that offshore wind power has gained significant attention and made substantial progress in recent years. The document also mentions the global installed wind capacity and the role of China in offshore wind power generation. It emphasizes the need to address the cost challenges associated with offshore wind power and mentions various challenges and considerations in the construction and operation of offshore wind farms. The document introduces a special issue that aims to promote research and development in offshore wind power and provides an overview of the articles included in the issue, covering topics such as blade icing, optimization of power collection systems, carbon fiber composites, multi-rotor wind turbines, and wind-speed variation patterns. The document encourages readers to explore these articles to expand their knowledge in the field of offshore wind power. This compilation of articles provides a comprehensive overview of wind turbine research, covering a wide range of topics including turbine blades, turbine structures, wind speed distribution, wake effects, and wind farm collection systems. The articles explore different aspects of wind turbine research, such as the materials and stability of turbine blades, the impact of icing on power loss, and the prediction of yawed wind turbine wakes using machine learning. The research presented in these articles contributes to the advancement of knowledge in the field and has implications for enhancing the efficiency and performance of wind turbines in practical settings [Extracted from the article]

Limited by scaling effects, the physical model tests of FOWTs (floating offshore wind turbines) cannot simulate the aerodynamic loads on rotors correctly. To solve this problem, the real-time hybrid model tests in wind tunnels were developed and provided a feasible solution for the aerodynamic simulation. To perform the wind tunnel tests, the design of aerodynamic equivalent rotor models is most critical. In this study, an innovative methodology of aerodynamic equivalent design for the wind turbine rotors is developed based on GA (genetic algorithm). The NREL (National Renewable Energy Laboratory) 5 MW and DTU (Technical University of Denmark) 10 MW rotors are employed for the case studies to validate the proposed methodology. According to the results, the model-scale aerodynamic thrust performance can be accurately matched with the prototype in the entire region between cut-in and cut-out wind speeds, which allows the rotor model to provide correct thrust at different wind speeds. The variance of the aerodynamic torque with the wind speeds for the developed model is also in good agreement with the prototype, which could be beneficial for the design of the model-scale active pitch control strategy. Moreover, the applicability of the fitness functions of GA is discussed. [ABSTRACT FROM AUTHOR]

The pace of locomotor development is a critical component of lifetime evolutionary fitness. Developmental researchers often divide species into two broad categories based on functional competence at birth: precocial infants who can independently stand and locomote soon after birth versus altricial infants who are either incapable of independent movement or can only do so in a rudimentary manner. However, investigating the lower level neuromotor and biomechanical traits that account for perinatal variation in motor development is complicated by the lack of experimental control inherent to all comparative analyses. Precocial and altricial animals often differ along a host of dimensions that can obfuscate the specific factors controlling motor development per se. Here, we propose an alternative approach of examining locomotor development in a nominally precocial species—the domestic pig (Sus scrofa)—in which gestation length has been experimentally manipulated, thereby creating "functionally altricial" cohorts for comparison. We have used standard biomechanical testing to evaluate balance and locomotor performance in preterm pigs born at 94% full-term gestation (N  = 29 individuals) and compared these data to a similar dataset on age-matched full-term piglets (N  = 15 individuals). Static balance tests showed that preterm pigs were characterized by increased postural sway, particularly in the fore-aft (anteroposterior) direction. Locomotor analyses showed that preterm piglets tended to take shorter, more frequent strides, use higher duty factors, and preferentially choose gait patterns that ensured they were supported by at least three limbs during most of the stride cycle, though differences between preterm and full-term animals were often modulated by variation in locomotor speed. Morphometric analysis showed no differences in relative extensor muscle mass between preterm and full-term animals, suggesting that neurological immaturity might be more determinant of preterm piglet motor dysfunctions than musculoskeletal immaturity per se (though much work remains to be done to fully document the neuromotor phenotype of the preterm infant pig model). In many ways, the postural and locomotor deficits shown by the preterm piglets paralleled the locomotor phenotype of altricial mammals. Overall, our study demonstrates the utility of a "within-species" design for studying the biomechanical correlates and neuromotor basis of evolutionary variation in motor skill at birth. [ABSTRACT FROM AUTHOR]

Utilization of urban blue-green spaces had been recognized as an environmentally friendly and politically acceptable approach to mitigate global warming. However, the evidence and hence knowledge of how the spatial pattern of urban blue–green space at city-level affects its cooling efficiency are limited. Therefore, in this paper, we are devoted to clarifying the cooling mechanism of urban blue–green space from the perspective of composition and distribution pattern. To do that, the Yangtze River Economic Belt, which had experienced significant environmental deterioration and contained rich blue–green resources, was taken as the case study site. Besides, the panel regression models and a new quadratic-curve-fitting based threshold effect estimating model were constructed to investigate the impact of spatial pattern of blue–green space on its holistic cooling intensity at city-level and to estimate the optimal spatial layout of blue–green spaces with maximum cooling efficiency. The results evidenced that the proportion and distribution characteristics of forests and shrublands in urban areas improved the intensity of urban cold island effect significantly, while that of grassland and water bodies mitigated urban heat island effect. Moreover, it was demonstrated that the city-level spatial pattern of urban blue–green space has a greater influence on its cooling efficiency at specific time periods (summer and daytime) and regions (mountainous cities with a small population). In addition, it was estimated that the cooling effect reaches the local maximum (around 1.2 ℃) when the PLAND / LSI index of forests, shrublands, grasslands, and water bodies at city-level is about 20%, 0.1%, 42.5% and 15.4% / 38.25, 5.08, 48.25 and 8.54, respectively. We believe our findings contribute significantly to the understanding on the link between ecological land elements and sustainable development of urban ecosystem. [ABSTRACT FROM AUTHOR]

Compact cities, characterized by high density and accessibility with fully developed inner-city public transport, are widely discussed and practiced around the world in response to the challenges of sustainable development and global warming. On this basis, we are committed to answering the question of how cities with varying urban growth rates adopt different policy practices, and whether these practices contribute to achieving the goal of building a sustainable, low-carbon city. Specifically, this study assesses the theoretical evidence and practical experiences on the effect of compact city characteristics and policies on urban CO2 emissions using a focused literature review and representative case studies. The results illustrate that public transportation is often strengthened in compact city policies and the density and spatial configuration of cities has a significant impact on urban carbon emissions. Moreover, there are significant differences within the impact mechanisms of compact cities on carbon emissions between small-medium-sized cities (dealing with aging populations and resource waste) and megacities (dealing with excessive urban sprawl). However, there is still insufficient quantitative evidence on the effectiveness of compact city policies and this review provides insights into future compact city planning toward policy approaches which yield lower carbon emissions. [ABSTRACT FROM AUTHOR]

The new way of offshore operation and maintenance based on unmanned ships has outstanding advantages. Aiming at the problem of lack of overall understanding of the complex environment above and under the water surface during the operation and maintenance of unmanned ships, a stitching and fusion technology of overwater and underwater visual images for unmanned ships is proposed. The software and hardware framework of the overwater and underwater visual image fusion system is constructed, the image processing methods in different environments are defined, and the accurate acquisition of obstacle information is realized. In the two experimental scenarios, the stitching accuracy of the obstacle model based on an extended neighborhood method can reach more than 85% within the obstacle distance of 8 m and more than 80% within the obstacle distance of 14 m. An image-driven Frustum–PointNets detection algorithm is proposed to obtain comprehensive obstacle avoidance information. In addition, the average accuracy of the three-dimensional detection of the algorithm is up to 91.40%. These results are significant and have a good reference value, as it demonstrates that the stitching and fusion method can effectively obtain the comprehensive information of overwater and underwater objects for unmanned ship. [ABSTRACT FROM AUTHOR]

The nonlinear dynamic behaviour of steep wave riser (SWR) subjected to the top harmonic motions considering the effect of the internal flow is numerically investigated using a three-dimensional (3D) time-domain finite element method (FEM) based on the slender flexible rod theory. In this numerical model, the riser which satisfies geometric nonlinearity is divided into three segments: decline segment, buoyancy segment and hang-off segment and the effect of the internal flow is also incorporated into motion equation using plug flow. A Newmark-β integral method is applied to update the dynamic responses at each time step. The published results for the static/dynamic performance of the steel flexible riser are used to validate the present numerical method. Numerical simulations are conducted to investigate the dependence of the tension, displacement and bending moment on the design parameters. The top motion amplitude/period, buoyancy length and internal flow density/velocity/top pressure are discussed respectively. [ABSTRACT FROM AUTHOR]

Hypertension is a common chronic disease, which leads to cardio-cerebrovascular diseases, and its prevalence is increasing. The cyclic adenosine monophosphate (cAMP)-protein kinase A (PKA) pathway participates in multiple cardiovascular diseases. Phosphodiesterase (PDE) 4 has been shown to regulate PKA activity via cAMP specific hydrolysis. However, whether PDE4-cAMP-PKA pathway influences hypertension remains unknown. Herein, we reveal that PDE4D (one of PDE4 isoforms) expression is upregulated in the aortas of experimental hypertension induced by angiotensin II (Ang II). Furthermore, knockout of Pde4d in mouse smooth muscle cells (SMCs) attenuates Ang II-induced hypertension, arterial wall media thickening, vascular fibrosis and vasocontraction. Additionally, we find that PDE4D deficiency activates PKA-AMP-activated protein kinase (AMPK) signaling pathway to inhibit myosin phosphatase targeting subunit 1 (MYPT1)-myosin light chain (MLC) phosphorylation, relieving Ang II-induced SMC contraction in vitro and in vivo. Our results also indicate that rolipram, a PDE4 inhibitor, may be a potential drug for hypertension therapy. Fan, Hou et al. investigate the role of phosphodiesterase (PDE) 4 and the PDE4-cAMP-PKA pathway on hypertension, reporting that PDE4D is upregulated in hypertension induced by angiotensin II. The authors also show that Pde4d knockout in mouse SMCs attenuates Ang II-induced hypertension and implicate AMPK signalling and MYPT1-MLC phosphorylation in Ang II-induced SMC contraction. [ABSTRACT FROM AUTHOR]

With the advent of the Big Data era, multi-source geo-tagged data provide a new perspective and data source for urban spatial analysis. In order to accurately identify the location and characteristics of consumer clusters in urban area and explore their formation mechanism, this study collects Sina Weibo check-in data and Dianping.com electronic word of mouth (e-WOM) data generated in the catering consumer space in the core region of Pearl River Delta, Guangdong and identifies location and characteristics of clusters with the help of DBSCAN clustering algorithm and CSA indices. In addition, the formation mechanism of these catering space clusters is explained by non-spatial and global spatial regression models. The result revealed that 4 levels of 19 catering space clusters are identified in the study area. The size and heat of consumer clusters are mainly affected by the geometric form, diversity of check-in, population density, distance from the city center and e-WOM corresponding to each cluster. The present study suggests that the new DBSCAN-based clustering method has a high accuracy. Compared with the traditional factors that reflect the objective attributes of cities and non-spatial models, the unstructured information elements contained in e-WOM and spatial error models can better explain the formation mechanism of the consumer clusters. [ABSTRACT FROM AUTHOR]

Wave loads estimation and structural strength evaluation are the fundamental work at the ship design stage. The hydroelastic responses and slamming strength issues are also concerned especially for large-scale high-speed ships sailing in harsh waves. To accurately predict the wave-induced motions and loads acting on the ship sailing in regular waves, a fully coupled 3D time-domain nonlinear hydroelasticity theory is developed in this paper. The vibration modal characteristics of the flexible hull structure derived by the 3D finite element method (FEM) and simplified 1D nonuniform Timoshenko beam theory are firstly described. The hydrostatic restoring force and hydrodynamic wave force are calculated on the real-time wetted surface of hull to address geometric nonlinearity due to the steep wave and large amplitude motions. The bow slamming and green water loads acting on the ship in severe regular waves are estimated by the momentum impact method and dam-breaking method, respectively. Moreover, a small-scaled segmented ship model is designed, constructed, and tested in a laboratory wave basin to validate the hydroelasticity algorithm. The results predicted by theoretical and experimental approaches are systemically compared and analyzed. Finally, future work for predictions of ship hydroelasticity and slamming loads in irregular waves is prospected. [ABSTRACT FROM AUTHOR]

This paper presents the probability distribution of the slamming pressure from an experimental study of regular wave slamming on an elastically supported horizontal deck. The time series of the slamming pressure during the wave impact were first obtained through statistical analyses on experimental data. The exceeding probability distribution of the maximum slamming pressure peak and distribution parameters were analyzed, and the results show that the exceeding probability distribution of the maximum slamming pressure peak accords with the three-parameter Weibull distribution. Furthermore, the range and relationships of the distribution parameters were studied. The sum of the location parameter D and the scale parameter L was approximately equal to 1.0, and the exceeding probability was more than 36.79% when the random peak was equal to the sample average during the wave impact. The variation of the distribution parameters and slamming pressure under different model conditions were comprehensively presented, and the parameter values of the Weibull distribution of wave-slamming pressure peaks were different due to different test models. The parameter values were found to decrease due to the increased stiffness of the elastic support. The damage criterion of the structure model caused by the wave impact was initially discussed, and the structure model was destroyed when the average slamming time was greater than a certain value during the duration of the wave impact. The conclusions of the experimental study were then described. [ABSTRACT FROM AUTHOR]

Physical model experiments of floating facilities in deep and ultra-deepwater with full-depth mooring system present obstacles because no wave basin is sufficiently large to perform model testing in reasonable scale. Truncation of full-depth mooring system is required for model test. Based on both statics and mooring-induced damping equivalence, truncated mooring lines are designed. A model test of a semi-submersible platform with full-depth and truncated mooring system is presented in this paper. In general, good agreements between the motion responses of semi-submersible platform with full-depth and truncated mooring system are found based on the model test results. [ABSTRACT FROM PUBLISHER]

An innovative approach is developed to design equivalent truncated mooring system for hybrid model testing. Considering the gravity, tension, current force and mooring line extension, the piecewise extrapolating method is employed to the static analysis of the multi-component mooring line. In addition, the quasi-static approach and dissipated energy model are used to figure out the mooring-induced damping of mooring system. Employing genetic algorithm, an optimised design program is developed to design equivalent truncated mooring system based on the similarity of both static and damping characteristics. Considering the catenary, semi-taut and taut mooring systems used for some semi-submersible platform of 1500 m water depths, equivalent truncated mooring system is designed by using the design program in this paper, respectively. The results prove that the design program is available for all common types of deep water mooring system and can be used for hybrid model testing. [ABSTRACT FROM PUBLISHER]

Improving the quality of forest, water, farmland, and other types of land use with outstanding ecosystem optimization, restoration functions (ecological lands) and reducing anthropogenic carbon emissions are recognized as the two main approaches of current mainstream climate change policies. The paper aims to evaluate and compare the value neutrality within these two main types of policy responses to climate change. To do that, a case study was conducted at the Yangtze River Economic Belt, China. We first summarized the implementation status of all climate change policies in the study area and collected data related to climate and economy at the policy pilot sites. Next, the coupling relationship between climate and socio-economic conditions at policy pilot sites was calculated by the Tapio model. Finally, we constructed dummy variables that reflected the status of policy implementation, to estimate the value neutrality of mainstream climate change policies and their impact on the coupling relationship by DID models. The results showed that the proportion of policies related to ecological lands that significantly improved the coupling degree between climate and socio-economic conditions of the pilot sites is more than that of carbon emission-related ones. Moreover, the average coupling degree between climate and socio-economic conditions of the pilot sites of ecological land policies was significantly increased by 3.99 units after policy implementation, which is 27.8% higher than that of carbon emission reduction policies. Generally, the two main findings directly evidenced that the climate change policies aimed at improving the area and quality of ecological lands were more conducive to the coupling development of the climate–economy nexus than the policies focusing on restricting carbon emissions, which provides important enlightenment for the establishment of relevant environmental policies around the world. [ABSTRACT FROM AUTHOR]