bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Coronal Discoloration Induced by White MTA and CEM Cement
Authors: Adel Mamak , Aflaki Sareh , Eghbal Mohammad Jafar , Darvish Alireza , Golshiri Amanda Mandana , Moradi Majd Nima , Reda Rodolfo , Tofangchiha Maryam , Zanza Alessio , Testarelli Luca
Published: December 2022

Coronal discoloration of endodontically treated teeth is a challenge in clinical dentistry. This study aimed to compare coronal discoloration induced by White Mineral Trioxide Aggregate and Calcium-enriched mixture cement. Fifty single-rooted, unrestored premolar teeth extracted for orthodontic reasons were selected. After access cavity preparation, all the root canals were instrumented with MTWO rotary files up to #40.6%. The specimens were randomly assigned to two experimental groups, White Mineral Trioxide Aggregate and Calcium-enriched mixture cement groups (n = 20), and two control groups (n = 5). In the White Mineral Trioxide Aggregate and Calcium-enriched mixture cement groups, the material was condensed via the access cavity 3 mm below the cementoenamel junction to a thickness of 3 mm. Tooth color was assessed using computer analysis of digital images. Tooth color measurements were recorded at eight time intervals: before material placement (but after tooth preparation), at 24 h, 48 h, one week, two weeks, four weeks, eight weeks, and sixteen weeks after material placement. Data were analyzed using t-test, ANOVA, repeated measure ANOVA, and Tukey HSD tests. The significance level was set at 5% for all the tests. Cervical discoloration of teeth in both experimental groups significantly increased over time (p < 0.05). However, samples in the White Mineral Trioxide Aggregate group showed more discoloration in cervical regions than Calcium-enriched mixture cement specimens after two, four, eight, and sixteen weeks (p < 0.05). Applying both White Mineral Trioxide Aggregate and Calcium-enriched mixture cement induced coronal discoloration; however, White Mineral Trioxide Aggregate samples exhibited greater cervical discoloration than Calcium-enriched mixture cement specimens after two, four, eight, and sixteen weeks.
Three-Dimensional Thermo-Mechanical Elastic Analysis of Functionally Graded Five Layers Composite Sandwich Plate on Winkler Foundations
Authors: Kardooni Mohammad Reza , Shishesaz Mohammad , Mosalmani Reza
Published: December 2022

In this work, the first shear deformation theory (FSDT) is used for the thermo-mechanical analysis of a simply supported five-layer functionally Graded (FG) sandwich plate resting on a Winkler elastic foundation. The sandwich plate consists of five layers (two functionally graded face sheets (AL−AL2O3), with aluminum (Al) as the metal and Alumina (AL2O3) as ceramic phases. Two vinyl ester adhesive layers bond the face sheets to an Elastollan core. The governing equations are obtained using the principle of virtual displacements. A uniform distributed load q with constant magnitude is applied on the top face sheet while all layers experience a steady temperature equal to T. We adapted layerwise theory (LT) to solve each layer’s stress distribution. Navier solution is employed to produce the semi-analytical solution results, which are compared with those of three-dimensional finite element analysis obtained by ABAQUS software. A parametric study is presented to observe the effect of the material gradation, variation in plate dimensions, variation in the thermo-mechanical load, and elastic foundation on the deflections and stresses in the functionally graded sandwich plate. For a composite sandwich plate with mechanical load, in the absence of thermal load, results of the first-order shear layer theory obtained by using the Navire method are relatively good in comparison to the normal stresses obtained for investigated points, which are obtained by finite element.
Bored, Distracted, and Confused: Emotions That Promote Creativity and Learning in a 28-Month-Old Child Using an iPad
Authors: Khalaf Shiva , Kilani Hechmi , Razo Melissa B. , Grigorenko Elena L.
Published: December 2022

Digital technology is increasingly becoming a part of daily life, including the lives of children. Portable digital devices are omnipresent and integrated into activities that did not previously require them. The related skills are often referred to as 21st-century skills, constituting a new type of literacy: digital literacy. These devices and skills bring unique, innovative elements to the learning experience; yet, we do not know the extent to which behavior, emotion, and socialization are affected by such experience. For preschool-aged children, interactions with digital devices and games for the purposes of learning can lead to a state of confusion and boredom, an emotional driving force that may generate mind-wandering and exploration, which, in turn, may facilitate learning. Our interdisciplinary observational case study examined the behavioral patterns linked to digital game-based learning (DGBL) by observing how a child’s mind-wandering contributed to iPad use when they were allowed to freely engage with the device and explore independently during the learning process. Building on a previous case study of a 28-month-old boy, “Ryan”, we evaluated the effects of bouts of mind-wandering as he played various DGBL applications (apps) by examining the length of time that Ryan exhibited relevant affective and behavioral states, iPad manipulations, and social interaction during the playtime. Ryan’s interactions with the iPad were video recorded for five weeks, and the video footage was coded using a detailed rubric. The results indicated that negative emotions, such as boredom, distraction, and confusion, if coupled with attentiveness and persistence, led to positive mind-wandering and positive learning outcomes. However, when boredom was coupled with frustration, it led to negative mind-wandering and a lack of learning outcomes. In conclusion, our study presents evidence that DGBL apps may improve learning by capitalizing on positive and avoiding negative mind-wandering.
Modeling of Thermodynamic Consolidation of Sea Ice Ridges Drifting in the Water with Changing Temperature
Authors: Marchenko Aleksey
Published: December 2022

Oceanographic and ice conditions in the region of Spitsbergen Bank in the Barents Sea were investigated in research cruises of the “Polarsyssel” in 2017–2019. Trajectories of ice drift were constructed using GPS data of the buoys deployed on the floes in the research cruises. The duration of the ice season in the region was analyzed using ice charts. The air temperature and wind velocities were analyzed using the data of meteorological stations on Bear Island and Hopen Island. Fieldwork on drifting ice showed the existence of thick consolidated floes with drafts up to 8 m, which were identified as completely consolidated sea ice ridges. The presence of such floes is dangerous for winter navigation along Spitsbergen Bank. A model of thermodynamic consolidation of ice ridges was formulated to investigate the thermodynamic evolution of ice ridges. The observed air and sea water temperatures were used in the boundary conditions on top and bottom surfaces of sea ice rubble. It was shown that the regular interaction of sea ice rubble with Atlantic and Arctic waters in the region of Spitsbergen Bank leads to almost complete consolidation of the ice rubble with an initial macro-porosity 0.2 for 150 days.
CFD Simulations of the Effect of Equalizing Duct Configurations on Cavitating Flow around a Propeller
Authors: Ng’aru Joseph Mwangi , Park Sunho
Published: December 2022

This study presented the results of a computational study of cavitating flows of a marine propeller with energy saving equalizing ducts. The main purpose of the study was to estimate the cavitating flows around a propeller with a duct, and to investigate the interaction between a duct and a propeller in cavitating flows. The INSEAN E779A propeller was used as a baseline model. Validation studies were conducted for non-cavitating and cavitating flows around a hydrofoil and a propeller. A comparison with the experimental data showed good agreement in terms of sheet cavity patterns and propulsion performances of the propeller. Various duct configurations have been presented, and it was found that a duct in front of the propeller had effects on the propeller’s cavitation and propulsion performance. Higher angles of attack of the duct showed a significant effect on the propeller’s cavitation behavior, especially with a small duct. The small duct lowered the cavitation inception radius with increase in angle of attack of the duct, while the large duct had more effect on the tip cavitation. The propeller with large duct gave higher thrust, however, the higher torque loading affected the propeller efficiency. Overall, it was found that the propeller with small duct provided a higher propeller efficiency
APSO-MPC and NTSMC Cascade Control of Fully-Actuated Autonomous Underwater Vehicle Trajectory Tracking Based on RBF-NN Compensator
Authors: Bao Han , Zhu Haitao , Li Xinfei , Liu Jing
Published: December 2022

In this paper, a model predictive control (MPC) method optimized by an adaptive particle swarm optimization (APSO) algorithm is proposed. Combined with non-singular terminal sliding mode control (NTSMC), the inner and outer double-closed-loop control system is constructed to solve the fully actuated autonomous underwater vehicle (AUV) dynamic trajectory tracking control problem. First, the outer loop controller generates the expected optimal velocity commands and passes them to the inner loop velocity controller, which generates the available control inputs to ensure the entire closed-loop trajectory tracking. In the controller design stage, system input and state constraints are effectively considered. After that, a compensator based on an adaptive radial basis function (RBF) neural network (NN) is designed to compensate for the model error and external sea state disturbances and to improve the control accuracy of the system. Then, the stability of the proposed controller is proved based on Lyapunov analysis. Finally, the dynamic trajectory tracking performance of an AUV with different sea state disturbances is verified by simulation, and the simulation results are compared with double-closed-loop PD control and cascade control of standard MPC based on PSO and SMC. The results show that the designed controller is effective and robust.
Numerical Study on the Interaction between Ocean Current Power Generator and Unmanned Underwater Vehicle
Authors: Wang Shenggui , Sun Jiyuan , Zhao Bowen , Yun Yingying , Huang Bin
Published: December 2022

The unmanned underwater vehicle (UUV) can effectively utilize marine renewable energy after equipping the UUV with an accompanying power generator that improve its long-range endurance. In order to study the interaction between the UUV and the ocean current power generator, a coupled hydrodynamic model of the counter-rotating type turbine and the UUV hull was established. Based on the RANS model and the sliding grid method, this paper analyzed the influence of the ocean current power generator on the straight-ahead resistance and hydrodynamic coefficient of the UUV in the non-working state, and calculated the UUV yaw moment and its surrounding flow field characteristics with the power generator in the working state. Then, the effect of the drift angle on the performance of the counter-rotating type turbine was explored. The results show that the straight-ahead resistance of the UUV increased slightly after equipping the power generator, but the increase was within 14%, and the characteristics of the surrounding flow field of the UUV did not changed greatly. The difference in the linear hydrodynamic coefficients before and after equipping the UUV with the power generator was within 7%. At most drift angles, when the generator was in the working state, the yaw moment of the hull was greater than the condition when the generator was not equipped. Nevertheless, the overall trend of the two sides was similar, so the rotation of the counter-rotating type turbine did not reduce the stability of the hull in the moored state. In addition, when the drift angle was greater than 50°, the UUV hull had a great impact on the performance of the counter-rotating type turbine; the power coefficient CP and thrust coefficient CT increased by about 35.7% and 17.8%, respectively. This paper provides a good reference value for the design of the power generation mode of the UUV equipped with a counter-rotating type turbine.
How Do Gene Expression Patterns Change in Response to Osmotic Stresses in Kuruma Shrimp (Marsupenaeus japonicus)?
Authors: Li Yuquan , Zhang Zhihao , Wang Zhongkai , Deng Zhitong , Zhao Ruiyang , Sun Jinfeng , Hao Pengyuan , Zhang Long , Wang Xiaofan , Liu Fei , Wang Renjie , Cui Yanting
Published: December 2022

Euryhaline crustaceans cope with external salinity changes by mechanisms of osmoregulation. In the current study, we first cloned and confirmed the ORF sequences of the ion-transportation-related genes Na+/K+-ATPase α subunit (NKAα), cytoplasmic carbonic anhydrase (CAc), and V-type H+-ATPase G subunit (VHA-G), and water channels of aquaporins (AQP3, AQP4, and AQP11) from kuruma shrimp (Marsupenaeus japonicus). Further tissue expression patterns showed a higher expression of MjAQP4, MjCAc, MjNKAα, and MjVHA-G in the gills, as well as a higher expression of MjAQP3 and MjAQP11 in the intestine and muscle, respectively. Then, qPCR analysis was used to assess the mRNA expression levels of those osmoregulatory genes in both post-larvae and adult shrimp when they were exposed to acute salinity stress or salinity acclimation. The results revealed significantly decreased expression levels of MjAQP3, MjAQP11, MjNKAα, and MjCAc, and higher expression levels of MjAQP4 and MjVHA-G when the post-larvae shrimp were directly subjected to 10‰ or 50‰ salinity. Moreover, similar expression patterns were also observed in the post-larvae shrimp during the accommodation to 10‰ or 50‰ salinity. As to the adult shrimp, significantly higher expression levels of those genes were observed in the gills after exposure to 10‰ salinity, whereas only the expression levels of MjAQP3, MjAQP11, and MjNKAα were up-regulated in the gills at 40‰ salinity. In contrast, the expression of MjVHA-G was significantly decreased at 40‰ salinity. Finally, during the acclimation to 10‰ salinity, the expression levels of MjAQP3, MjAQP11, and MjNKAα were also significantly elevated, while the expression of MjCAc was significantly decreased in the gills. In addition, the expression levels of MjAQP3, MjAQP4, MjCAc, and MjVHA-G were significantly decreased in the gills during the acclimation to 55‰ salinity. The findings of the study suggest that the examined genes are critical for the adaptation of aquatic crustaceans to changing environmental salinity. Our study lays as the foundation for further research on osmoregulation mechanisms in M. japonicus.
Potential Influence of Offshore Wind Farms on the Marine Stratification in the Waters Adjacent to China
Authors: Lian Zhan , Liu Kun , Yang Tong
Published: December 2022

Offshore wind farms (OWFs) can influence marine stratifications, leading to fuel nutrition in the upper ocean and regulating ocean carbon fluxes. Evaluating this dynamic effect facilitates the planning of OWFs deployment for enlarging marine carbon sequestration, which is urgent in the pursuit of China’s carbon neutrality targets. However, it is impossible to observe the target influence in the planning stage of deployments, and it is impractical to build a high-resolution (100~101 m) model to cover the entire waters adjacent to China. The theoretical calculations, therefore, are the first step and top priority. The simplified theory presents two suggestions in the design of future OWF deployments in the study area. The first suggestion is made from the perspective of OWF positioning. To the east of the cities of Zhoushan, Putian, and Shantou, the oceans are dynamically sensitive to OWF deployments. The second suggestion is made from the perspective of the length scale of OWFs. A broader OWF results in a smaller vertical disturbance in the coastal waters, but the situation is opposite in the open seas. The OWF deployment strategy, proposed in the aim of ensuring idealized marine stratification responses, thus varies geographically. This study provides a panoramic view of the sensitivity of marine stratification to OWFs in the study regions. It can be seen as a steppingstone in detailed research of the target phenomenon.
Dumbbell-Shaped Damage Effect of Closed Cylindrical Shell Subjected to Far-Field Side-On Underwater Explosion Shock Wave
Authors: Wang Yuhao , Dong Hongxiao , Dong Tong , Xu Xiangyun
Published: December 2022

In naval warfare, underwater explosion (UNDEX) shock waves significantly influence the stability and safety of the pressure hull structure of the equipment. This study investigated the unique dynamic buckling of a closed cylindrical shell subjected to a far-field side-on UNDEX shock wave using a three-dimensional numerical simulation based on acoustic–structural arithmetic. In particular, the flow-field response characteristics, plastic deformation, and yield characteristics of the cylindrical shell were determined under the influence of the UNDEX shock wave. Subsequently, the failure mode of the cylindrical shell was analyzed to propose the dumbbell-shaped damage effect. The results revealed that when the UNDEX shock wave encounters a finite cylindrical shell, the fluid exhibits a perturbation such as pressure division, stress wave deflection, and flow in the surroundings of the circular cylinder. However, the fluid cannot produce a sizeable instantaneous displacement that yields certain strong constraints at both ends of the cylindrical shell. These constraints generate an irregular distribution of the flow field pressure, and the cylindrical shell tends to exhibit an “arch” deformation along the direction of shock wave propagation. Owing to the flow surrounding the circular cylinder, a negative pressure zone is generated in the flow field at both ends of the cylindrical shell, which induces a “sucking disc” shape at both ends of the cylindrical shell and ultimately produces a dumbbell-shaped damage effect. The present findings will aid in the structural design and impact resistance of submarines, unmanned undersea vehicles, and additional equipment under the impact load of the UNDEX.
A New Approach to Integrated Multi-Trophic Aquaculture System of the Sea Cucumber Apostichopus japonicus and the Sea Urchin Strongylocentrotus intermedius
Authors: Hu Fangyuan , Wang Huiyan , Tian Ruihuan , Gao Jujie , Wu Guo , Yin Donghong , Zhao Chong
Published: December 2022

The sea cucumber Apostichopus japonicus and the sea urchin Strongylocentrotus intermedius are two commercially important species and are widely cultured in China. Here, a laboratory experiment was conducted for 34 days to assess whether the survival, growth and behavior performances are better in the new commercially valuable integrated multi-trophic aquaculture (IMTA) system (group M, 90 S. intermedius and 37 A. japonicus/10,638 cm3 of stocking density) than those in the control group for sea urchins (group U, 90 S. intermedius/10,638 cm3 of stocking density) and the control group for sea cucumbers (group C, 37 A. japonicus/10,638 cm3 of stocking density). We found that feeding behavior, crawling behavior, body length and body weight of sea cucumbers were significantly greater in group M than those in group C. These results suggest that the new IMTA system improves fitness-related behaviors and consequently leads to a better growth in A. japonicus while maintaining a high biomass. We further found that group M showed significantly larger body size and Aristotle’s lantern reflex as well as significantly lower mortality and morbidity in sea urchins, compared to those in group U. This suggests that the new IMTA system greatly improves feeding behavior and body growth, and survival of cultured S. intermedius. This IMTA system is a promising candidate to promote the production efficiency of juvenile A. japonicus (as primary species) and S. intermedius (as subsidiary species) in China.
Fatigue Strength Assessment of Single-Sided Girth Welds in Offshore Pipelines Subjected to Start-Up and Shut-Down Cycles
Authors: Dong Yan , Ji Guanglei , Fang Lin , Liu Xin
Published: December 2022

During the service life of offshore pipelines, many start-up and shut-down cycles take place, possibly leading to significant cyclic loads. Fatigue failure may occur, resulting in serious environmental pollution and loss of property. The study aims to assess the fatigue strength of single-sided girth welds in offshore pipelines under these specific fatigue loads. The longitudinal stress range caused by the variation of the pipeline’s internal pressure and temperature is calculated. The effective notch strain approach is used to assess the fatigue strength of welds. The plastic behaviour of the weld root is investigated for a study case to justify the use of low-cycle fatigue assessment approaches. The effect of weld root geometry on the notch stress factor is studied to identify the dominant geometrical parameters. The fatigue strength of the study case is assessed, and some limitations of the assessment are discussed. The results show that the plastic behaviour of the weld root is only significant for severe local stress concentrations, which is mainly governed by the axial misalignment, weld root angle and the weld root bead width. If the fatigue damage at failure is 0.1, a limited number of start-up and shut-down cycles are allowed during the service life of the pipeline for the study case, indicating the necessity of fatigue strength assessment.
Application of SWASH to Compute Wave Overtopping in Ericeira Harbour for Operational Purposes
Authors: Manz Anika , Zózimo Ana Catarina , Garzon Juan L.
Published: December 2022

This work aimed at testing the capability of the numerical model SWASH to be implemented in the prototype of the overtopping and flooding forecast system HIDRALERTA for Ericeira harbour. In contrast to the neural network NN_OVERTOPPING2, which is currently implemented in HIDRALERTA, SWASH is able to estimate the flood extension and wave propagation along the domain, which makes it a possible improvement to NN_OVERTOPPING2. The one-dimensional version of the SWASH model was implemented to simulate overtopping at two different profiles (antifer and tetrapods) and calibrated for three storms in 2019 by comparing the simulated overtopping discharge to NN_OVERTOPPING2 results. For the calibration, the Manning coefficient was used to represent the friction of the armour layer. Then, for operational purposes, four expressions to calculate the Manning coefficient were developed based on: the relative crest freeboard, the wave steepness, the incident wave angle and the type of armour layer. The expressions showed small errors between the calculated and calibrated Manning coefficients and highlighted the importance of the incident wave angle to obtain an accurate calibration. Despite an underestimation of the overtopping discharge in some cases, the SWASH model was found to provide overall good results when applied with calculated Manning coefficients and suitable to be implemented in HIDRALERTA.
Application of Flexible Structure in Marine Engineering
Authors: Mohapatra Sarat Chandra
Published: December 2022

The aim of the Special Issue (SI) was to publish original and high-quality research papers that deal with model developments based on the mathematical, numerical, and experimental models associated with flexible floating or submerged structure applications in the discipline of marine engineering [...]
Marine Ancillary Diesel Engine Emissions Reduction Using Advanced Fuels
Authors: Puškár Michal , Tarbajovský Pavol , Lavčák Matúš , Šoltésová Marieta
Published: December 2022

Large transoceanic ships use marine ancillary diesel engines for generating electricity, which, on the other hand, produce a remarkable amount of harmful emissions during the combustion process. The International Maritime Organisation (IMO) establishes standards that limit the amount of harmful emissions produced during the engine combustion cycle in maritime transport. Because of this restriction, new alternative fuels entered the market. Experiments had been performed with various testing fuels created from biodiesel and ULSD-F (Ultra Low Sulphur Diesel-Fuel) in the ratios of 0%, 50%, 80%, and 100%. During the tests, the engine ran at different speeds and loads so that the mixed fuel influence on engine operation could be observed in detail and investigated.
An Open-Source Benchmark Simulator: Control of a BlueROV2 Underwater Robot
Authors: von Benzon Malte , Sørensen Fredrik Fogh , Uth Esben , Jouffroy Jerome , Liniger Jesper , Pedersen Simon
Published: December 2022

This paper presents a simulation model environment for the popular and low-cost remotely operated vehicle (ROV) BlueROV2 implemented in Simulink™ which has been designed and experimentally validated for benchmark control algorithms for underwater vehicles. The BlueROV2 model is based on Fossen’s equations and includes a kinematic model of the vehicle, the hydrodynamics of vehicle and water interaction, a dynamic model of the thrusters, and, lastly, the gravitational/buoyant forces. The hydrodynamic parameters and thruster model have been validated in a test facility. The benchmark model also includes the ocean current, modeled as constant velocity. The tether connecting the ROV to the top-site facility has been modeled using the lumped mass method and is implemented as a force input to the ROV model. At last, to show the usefulness of the benchmark model, a case study is presented where a BlueROV2 is deployed to inspect an offshore monopile structure. The case study uses a sliding mode controller designed for the BlueROV2. The controller fulfills the design criteria defined for the case study by following the provided trajectory with a low error. It is concluded that the simulator establishes a benchmark for future control schemes for position control and trajectory tracking under the influence of environmental disturbances.
Predicting the Motion of a USV Using Support Vector Regression with Mixed Kernel Function
Authors: Xu Pengfei , Cao Qingbo , Shen Yalin , Chen Meiya , Ding Yanxu , Cheng Hongxia
Published: December 2022

Predicting the maneuvering motion of an unmanned surface vehicle (USV) plays an important role in intelligent applications. To more precisely predict this empirically, this study proposes a method based on the support vector regression with a mixed kernel function (MK-SVR) combined with the polynomial kernel (PK) function and radial basis function (RBF). A mathematical model of the maneuvering of the USV was established and subjected to a zig-zag test on the DW-uBoat USV platform to obtain the test data. Cross-validation was used to optimize the parameters of SVR and determine suitable weight coefficients in the MK function to ensure the adaptive adjustment of the proposed method. The PK-SVR, RBF-SVR, and MK-SVR methods were used to identify the dynamics of the USV and build the corresponding predictive models. A comparison of the results of the predictions with experimental data confirmed the limitations of the SVR with a single kernel function in terms of forecasting different parameters of motion of the USV while verifying the validity of the MK-SVR based on data collected from a full-scale test. The results show that the MK-SVR method combines the advantages of the local and global kernel functions to offer a better predictive performance and generalization ability than SVR based on the nuclear kernel function. The purpose of this manuscript is to propose a novel method of dynamics identification for USV, which can help us establish a more precise USV dynamic model to design and verify an excellent motion controller.
Marine Radar Oil Spill Extraction Based on Texture Features and BP Neural Network
Authors: Chen Rong , Jia Baozhu , Ma Long , Xu Jin , Li Bo , Wang Haixia
Published: December 2022

Marine oil spills are one of the major threats to marine ecological safety, and the rapid identification of oil films is of great significance to the emergency response. Marine radar can provide data for marine oil spill detection; however, to date, it has not been commonly reported. Traditional marine radar oil spill research is mostly based on grayscale segmentation, and its accuracy depends entirely on the selection of the threshold. With the development of algorithm technology, marine radar oil spill extraction has gradually come to focus on artificial intelligence, and the study of oil spills based on machine learning has begun to develop. Based on X-band marine radar images collected from the Dalian 716 incident, this study used image texture features, the BP neural network classifier, and threshold segmentation for oil spill extraction. Firstly, the original image was pre-processed, to eliminate co-channel interference noise. Secondly, texture features were extracted and analyzed by the gray-level co-occurrence matrix (GLCM) and principal component analysis (PCA); then, the BP neural work was used to obtain the effective wave region. Finally, threshold segmentation was performed, to extract the marine oil slicks. The constructed BP neural network could achieve 93.75% classification accuracy, with the oil film remaining intact and the segmentation range being small; the extraction results were almost free of false positive targets, and the actual area of the oil film was calculated to be 42,629.12 m2. The method proposed in this paper can provide a reference for real-time monitoring of oil spill incidents.
Study on Impact Load and Head Cap Load Reduction Performance of Vehicle Entering Water at High Speed
Authors: Zhao Hairui , Shi Yao , Pan Guang , Huang Qiaogao
Published: December 2022

Aiming at the problem of high-speed entry of vehicles with a diameter of 200 mm, a numerical model of high-speed entry of vehicles is established based on the arbitrary Lagrange–Euler (ALE) algorithm, and the numerical simulation of high-speed entry of flat-nosed and round-nosed vehicles is carried out. On this basis, the experimental research on the entry of vehicle with buffer caps is carried out. The following conclusions are obtained through simulation. The peak value of the axial load of the vehicle raises with the increase of the inlet velocity and angle, while the stable value only raises with the increase of the inlet velocity. The impact load on the round-nosed vehicle is obviously smaller than that on the flat-nosed vehicle when the water entry angle is greater than 80°. The peak value of axial load can be reduced by 22% when entering water vertically at 100 m/s. The following conclusions are obtained through experiments. The buffer head cap has a significant load reduction effect. It shows compaction, cracks and breakage under the impact of water. These processes can absorb part of the impact energy, reduce the peak value of axial load and increase the pulse width. The load reduction rate grows from 4.7% to 18.5% when the length of the buffer head cap is increased from 200 mm to 300 mm while the water inlet speed is the same. The damage level of the head cap increases sharply, and the load reduction rate raises when the water entry speed is increased while the length of the buffer head cap is the same.
A Cost–Benefit Approach to Discuss Artificial Nourishments to Mitigate Coastal Erosion
Authors: Coelho Carlos , Lima Márcia , Ferreira Margarida
Published: December 2022

Worldwide, artificial nourishments are being considered as one of the main coastal erosion mitigation measures. However, this solution is not permanent, since the natural removal of sediments that occurs after the sand deposition leads to the need of re-nourishment projects; thus, its performance and longevity dependent on several design parameters (placement site and extension alongshore, frequency, and volume, etc.) In this work, a methodological approach for cost–benefit assessment is applied to analyze the performance of artificial nourishments from a physical and economical point of view, by analyzing the effectiveness of different scenarios. The study was developed considering two study areas: a hypothetical situation (generic study area) and a real coastal stretch (Barra-Vagueira, located in the Portuguese west coast). The findings show the complexity in defining the best nourishment option, being dependent on the wave climate, site specific conditions, and main goal of the intervention. The proposed cost–benefit approach allows one to obtain and compare the physical and economic performance of artificial nourishments to mitigate coastal erosion, aiding the decision-making processes related to coastal planning and management.
Experimental Analysis of CENTEC-TLP Self-Stable Platform with a 10 MW Turbine
Authors: Hmedi Mohamad , Uzunoglu Emre , Medina-Manuel Antonio , Mas-Soler Jordi , Vittori Felipe , Pires Oscar , Azcona José , Souto-Iglesias Antonio , Guedes Soares C.
Published: December 2022

This work evaluates the experimental test results regarding the operational performance of a free-float capable tension leg platform with a 10 MW wind turbine. It covers the platform dynamics in the selected installation area: Ribadeo, Spain. The model and the facility are initially presented, along with the experimental setup and the load cases. The testing campaign includes a software-in-the-loop method to emulate the rotor thrust and the aerodynamic and gyroscopic moments in pitch and yaw. The result sets are structured to start from basic information from system identification cases and continue with responses against regular and irregular waves accompanied by steady and stochastic wind scenarios. The performance in operational and extreme conditions is assessed as well as fault scenarios. The experiments demonstrate auspicious motion dynamics and mooring line behavior when examined against class society rules.
Evaluation of Resistance of Banana Genotypes with AAB Genome to Fusarium Wilt Tropical Race 4 in China
Authors: Zhan Ni , Kuang Mengyu , He Weidi , Deng Guiming , Liu Siwen , Li Chunyu , Roux Nicolas , Dita Miguel , Yi Ganjun , Sheng Ou
Published: December 2022

Banana cultivars with the AAB genome group comprise diverse subgroups, such as Plantain, Silk, Iholena, and Pisang Raja, among others, which play an important role in food security in many developing countries. Some of these cultivars are susceptible to Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4), the most destructive pathogen threatening banana production worldwide, and some of them are still largely unknown. We evaluated the resistance of 37 banana genotypes, including Plantain, Silk, Iholena, Maia Maoli/Popoulu, Pisang Raja, Pome, and Mysore, to Foc TR4 under both greenhouse and field conditions. Genotypes from the Silk and Iholena subgroups were highly susceptible to Foc TR4. Pome and Mysore showed resistance and intermediate resistance, respectively. However, Pisang Raja ranged from susceptible to intermediate resistance. One cultivar from the Maia Maoli/Popoulu subgroup was highly susceptible, while the other displayed significant resistance. Most Plantain cultivars exhibited high resistance to Foc TR4, except two French types of cultivar, ‘Uganda Plantain’ and ‘Njombe N°2’, which were susceptible. The susceptibility to Foc TR4 of some of the AAB genotypes evaluated, especially Plantain and other cooking bananas, indicates that growers dependent on these varieties need to be included as part of the prevention and integrated Foc TR4 management strategies, as these genotypes play a crucial role in food security and livelihoods.
Prediction of Soil Erodibility by Diffuse Reflectance Spectroscopy in a Neotropical Dry Forest Biome
Authors: Pontes Samuel Ferreira , Silva Yuri Jacques Agra Bezerra da , Martins Vanessa , Boechat Cácio Luiz , Araújo Ademir Sérgio Ferreira , Dantas Jussara Silva , Costa Ozeas S. , Barbosa Ronny Sobreira
Published: December 2022

The USLE and the RUSLE are two common erosion prediction models that are used worldwide, and soil erodibility (K-factor) is one parameter used to calculate them. The objectives of this study were to investigate the variability of soil-erodibility factors under different soil-texture classes and evaluate the efficiency of diffuse reflectance spectroscopy (DRS) in the near-infrared range at predicting the USLE and RUSLE K-factors using a partial least squares regression analysis. The study was conducted in Fluvisols in dry tropical forest (the Caatinga). Sampling was undertaken in the first 20 cm of soil at 80 sites distributed 15 m apart on a 70 m × 320 m spatial grid. Results show that the clay fraction is represented mainly by 2:1 phyllosilicates. Soil organic matter content is low (<0.2%), which is typical of tropical dry forests, and this is reflected in the high values of the calculated USLE and RUSLE K-factors. An empirical semivariogram was used to investigate the spatial dependence of both K-factors. Pedometric modeling showed that DRS can be used to predict both USLE (R2adj = 0.53; RMSE = 8.37 10−3 t h MJ−1 mm−1) and RUSLE (R2adj = 0.58; RMSE = 6.78 10−3 t h MJ−1 mm−1) K-factors.
The Relationship between Housing Price, Teacher Salary Improvement, and Sustainable Regional Economic Development
Authors: Shen Chaohai , Sheng Tong , Shi Xingheng , Fang Bingquan , Lu Xiaoqian , Zhou Xiaolan
Published: December 2022

In the post pandemic era, most of the countries are facing challenges in economic recovery, while investing in creative human capital such as teachers by increasing their salaries can be one of the policy options for governments to drive development. Housing price, however, may impact the working of these policies. Using the panel data of 31 provincial regions in China during 2006–2018, we evaluated the relationship between housing price, the improvement in teacher salary, and sustainable regional economic development. From the perspective of imbalanced regional development, we discovered the heterogeneity in the rate of return on education investment in terms of teacher salary. Higher teacher salary plays a more active role in the sustainable development of underdeveloped regions, and the crowding-out effect of housing price in Western China is the most intense. The results further provide some policy implications on efficiently promoting the coordinated development of sustainable regional economies by improving the creative human capital cultivators’ salaries. This paper verifies the significance of housing price dynamics from a new perspective based on educational investment. Overall, our study provides theoretical support for improving teachers’ income to promote regional economic development and further provides guidance for the government to carry out macro control to promote regional economic development with changes in housing price dynamics. Our study aims to link land systems, particularly the housing market, to sustainability and public policy.
Is There Herd Effect in Farmers’ Land Transfer Behavior?
Authors: Gao Jia , Zhao Rongrong , Lyu Xiao
Published: December 2022

China’s rural land transfer market has been plagued by issues including poor information transmission, limited scale, and an incoherent structure. In this context, this study collected the data of 337 farmers in Qufu City, Shandong Province, and incorporated into the analysis the acquaintance-based nature of rural society that includes strong geographic ties. Taking the herd effect as the starting point, this paper it considers how farmers in the same geo-network affect the land transfer behavior of individual farmers, and adopts the Probit model to analyze the impact of geo-networks to verify the function of the herd effect in farmers’ land transfer behavior. Then, the IV-Probit model is applied to solve the endogenous problem of the herd effect. The results show that: (1) Farmers imitate the land transfer behavior of other farmers in the same geo-network. Geo-networks positively impact the land transfer behavior of farmers, and the herd effect is apparent in farmers’ land transfer behavior. (2) Farmers’ family background, resource endowment, and cognitive features are key factors that influencing farmers’ land transfer behavior. (3) Farmers’ land transfer behavior is more significantly influenced in groups with low and middle agricultural income than in groups with high agricultural income. This study aims to assist the government in giving full play to the positive role of the herd effect, promoting the leading role of village cadres as leader sheep, and smoothing the transmission of land transfer information. Governments should place more emphasis on developing land transfer platforms and invest more in the construction of farmland infrastructure. This paper may serve as a reference to achieve large-scale agriculture operation via land transfer and promote the prosperity of the land transfer market.
Impacts of Fertilization on Environmental Quality across a Gradient of Olive Grove Management Systems in Alentejo (Portugal)
Authors: Rodríguez Sousa Antonio , Tribaldos-Anda Claudia , Prats Sergio , Brígido Clarisse , Muñoz-Rojas José , Rescia Alejandro
Published: December 2022

Olive groves are Mediterranean socioecological systems. In Portugal (350,000 hectares of olive groves), a transition is ongoing towards intensification. Such effects may arise from the incremental use of agrochemical fertilizers. The Alentejo region, Portugal, was stratified according to the olive management systems (i.e., extensive groves managed conventionally, integrated or organically, and intensive and highly intensive farms) and erosive states. Agronomic (i.e., fertilizers) and biological (i.e., herbaceous and lepidopteran richness and biodiversity) variables were quantified in 80 plots so we could know how managements affect biodiversity. Intensive and highly intensive farms showed the highest erosion (up to 48 t ha−1 year−1) and the highest concentration of nitrates (11–16 ppm), phosphates (8–15 ppm), and potassium (169–183 mg kg−1), aligned with its lower flora (null) and fauna (0.50–1.75 species). Conventional extensive farms attained an intermediate position, and integrated and organic managements showed the lowest erosion (up to 20 t ha−1 year−1), and the lowest concentration of nitrates (5–6 ppm), phosphates (2–4 ppm), and potassium (92–125 mg kg−1) aligned with its higher flora (14–27 species) and fauna (up to 8 species). Studies aimed at characterizing the multifunctionality of olive groves are essential in Portugal, also considering how soil practices can minimize externalities driven by rapid changes in crop systems.
Landsat-Satellite-Based Analysis of Long-Term Temporal Spatial Dynamics of Cyanobacterial Blooms: A Case Study in Taihu Lake
Authors: Li Jingtai , Liu Yao , Xie Siying , Li Min , Chen Li , Wu Cuiling , Yan Dandan , Luan Zhaoqing
Published: December 2022

Cyanobacterial blooms in large and shallow freshwater lakes have become one of the most severe ecological problems threatening the environment and public health. Although great progress has been made in Taihu Lake in cyanobacterial bloom monitoring, most previous studies have used MODIS images with a resolution greater than 250 m, available after 2000, while the fine-scale studies on its long-term spatio-temporal dynamics to date are insufficient. This study monitored the spatiotemporal distribution of cyanobacterial blooms in Taihu Lake between 1984 and 2021 using Landsat images of 30 m resolution on the cloud computation platform Google Earth Engine and calculated the cyanobacterial blooms’ area percentage and the cyanobacterial bloom frequency index. Then, we investigated the influence of water quality and meteorological factors on area and frequency using Spearman correlation and principal component analysis. The results show that cyanobacterial blooms spread from the northern to the central, western, and eastern parts of Taihu Lake from 1984 to 2021. With the exception of East Lake, the area and frequency of cyanobacterial blooms increased significantly. Hypereutrophic water conditions, high temperatures, abundant sunshine hours, and low wind velocities all favor cyanobacteria blooms in Taihu Lake, and the key influencing factors of dynamics in cyanobacterial blooms are the comprehensive trophic level index, annual sunshine hours, and annual maximum wind speed. This study can serve as a reference for lake eutrophication monitoring and water resource management and protection.
A Study on Policy and Institutional Arrangements for Urban Green Space Development in Ulaanbaatar, Mongolia
Authors: Enkhbold Bayarmaa , Matsui Kenichi
Published: December 2022

Globally, authorities in rapidly growing cities have struggled to find sufficient green space for residents. Ulaanbaatar city of Mongolia has faced a similar situation due largely to drastically shrinking open land, especially after adopting a market-oriented economy in 1990. Amid the escalating urban congestion and growing concerns over pollution that ensued, the concept of urban green spaces began to gain more attention among Ulaanbaatar city officials. In 2014, the national government introduced the Green Development Policy to set aside 30% of the city’s residential area as green space by 2030. The Ulaanbaatar 2020 Master Plan and Development Approach for 2030 similarly set goals to increase green space per capita to 30 m2. However, the current share of green space in the city is only 1.8% and 0.12–5 m2/person. Most case studies on urban green space policies and institutional arrangements focus on large cities in European countries with a relatively low population growth rate compared to those in developing countries. Therefore, this paper attempts to understand why Ulaanbaatar has not been able to increase green space despite its ambitious policy goals for many years. To do so, we examined the policy documents and institutional arrangements. We also conducted personal interviews with government specialists. As a result, we found four main challenges: (1) actions to increase green space were weak; (2) action plans were not clearly laid out for government officials to follow; (3) where stakeholder coordination was needed, administrators did not have sufficient resources and frameworks to do so, and (4) promised plans were not financially feasible. Overall, these findings indicate a necessity to strengthen urban green space monitoring and sufficient budget mobilization.
Landscape Modifications Ascribed to El Niño Events in Late Pre-Hispanic Coastal Peru
Authors: Delle Rose Marco
Published: December 2022

Coastal Peru, one of the driest deserts in the world, is a key region to investigate the connection between climate processes and Earth surface responses. However, the trends in space and time of the landscape effects of El Niño events throughout the last millennium are hard to outline. A deeper understanding of geological and archaeological data in pre-Hispanic time can help to shed light on some critical questions regarding the relationship between such a coupled atmosphere–ocean phenomenon and landscape modifications. The bibliographic sources required for this purpose are scattered throughout various disciplines, ranging from physical to human sciences, and thus comprehensive databases were used to identify and screen relevant studies. The performed examination of these documents allowed us to assess strengths and weaknesses of literature hypotheses and motivate additional studies on targeted research objectives.