The selection of retaining wall systems is still a challenging work due to the various uncertain factors in deep excavation. Previous studies indicate that machine learning technique is an intelligent auxiliary tool, capable of assisting engineers to select appropriate retaining wall systems at the early phase of a project. However, two potential limitations were identified in previous studies. First of all, the conventional machine learning model requires a large amount of dataset to derive reliable results, but the size of the dataset used in previous models was usually less than 300. Second, the prediction model used in previous studies was single model, but the risk of poor generalization easily emerges for single model, thereby, yielding inaccurate prediction results. Therefore, this paper put forward a stacking integrated model to solve the above problems. Stacking integrated model aggregates the advantages of multiple models. We have used the collected data from the questionnaire investigation to train and validate the presented model. The results showed that in the case of a small dataset size, the accuracy of this model was 87.59%, the recall rate was 65.23%, the precision was 79.16%, and the F-measure was 73.07%, which was improved compared to the other five models. This model has important guiding significance for the selection of retaining wall systems.

When wind turbines operate in high-latitude offshore regions, ice accumulation on blade surfaces can severely compromise the structural safety of turbines and reduce their power generation efficiency. To mitigate the adverse effects of ice accumulation on wind turbines, it is essential to evaluate the effectiveness of various anti-icing measures in offshore environments. Superhydrophobic materials, known for their environmental friendliness, high efficiency, and energy-saving advantages, have been widely used for anti-icing in onshore wind power generation. However, their direct application to offshore wind turbines is limited due to the presence of salt in offshore environments. In this study, laboratory-scale experiments were conducted to investigate the anti-icing performance of superhydrophobic surfaces under winter atmospheric conditions simulating China’s Bohai Sea. The experiments were divided into two phases. In the first phase, the ice accretion process and morphology of superhydrophobic surfaces were analyzed under different operating conditions. The second phase expanded on the first by further examining the icing process of droplets on these surfaces. The results indicate that both the salt content and wind speed significantly affect the anti-icing performance of superhydrophobic surfaces. Additionally, the salt content influences the critical droplet diameter required for detachment. This research provides insights into icing mechanisms and supports the development of anti-icing technologies for offshore wind turbine blades with superhydrophobic surfaces.

Road energy harvesting has become a research hotspot, and photovoltaic pavements have received greater attention, but challenges such as low surface carrying capacity and poor light transmission. To achieve efficient solar energy utilization, this research designs an under-bridge photovoltaic structure. The outdoor photoelectric effect test was used to investigate how the bridge orientation, reflective mirror angle, and pillar height affected the structure's power generating. The results show that: the bridge orientation, reflective mirror angle, and pillar height have a significant impact on the structure's output power; different bridge orientations and reflective mirror angle will result in different direct light received by the structure and the utilization rate of the reflective mirror. Considering the structural strength and cost comprehensively, the optimal pillar height is 1.2H. The daily power generation of the reflective under-bridge photovoltaic structure is 0.3183 kWh/m2, with a return on investment (ROI) of 50.85% and payback period of 11.72 years. The levelized cost of energy (LCOE) is 0.67 RMB/kWh, demonstrating significant economic benefits. Additionally, during the 20-year operation period, a reduction of 1462.21 kg/m2 in CO2 emissions is achieved, indicating substantial environmental benefits. This study provides a reliable reference for the future promotion and application of photovoltaic bridges.

In winter, stay cable sheaths are prone to icing, which increases cable loads and poses a falling-ice hazard upon thawing. While manual and chemical de-icing are common methods, their safety and cost drawbacks make robotic de-icing a promising alternative. Robotic de-icing offers a promising alternative. However, to protect the sheath from damage, the de-icing blade is designed to minimize contact with its surface. Consequently, a thin layer of residual ice is often left behind, which reduces the surface friction coefficient and complicates the climbing process. This study evaluates the climbing performance of a self-manufactured cable-climbing mechanism through laboratory tests and dynamic simulations (ADAMS). A physical prototype was built, and dynamic simulations of the cable-climbing mechanism were conducted using Automated Dynamic Analysis of Mechanical Systems (ADAMS) software. The preliminary validation results demonstrate that the mechanism is capable of maintaining stable climbing under extreme conditions, including a friction coefficient of 0.12 to reflect thin-ice variability and indicated stable climbing even at μ = 0.12), a vertical inclination of 90°, and a load of 12 kg, confirming the design’s validity. Furthermore, we analyzed key parameters. A lower friction coefficient requires a higher clamping force and adversely affects the climbing speed due to increased slip. Similarly, an increased payload elevates the mechanism’s deflection angle, spring force, and wheel torque, which in turn reduces the climbing speed. Cable inclination has a complex effect: deflection decreases with slope, yet clamping force peaks near 70°, showing a bell-shaped trend. This peak requirement dictated the damping spring selection, which was given a safety margin. This ensures safe operation and acceleration at all other angles. Limitations: The present results constitute a feasibility validation under controlled laboratory conditions and rigid-support simulations. The long-term effects of residual ice and field performance remain to be confirmed in planned field trials.

The spread of agriculture and population from Mainland East Asia to the islands of Southeast Asia and Oceania was the last far-reaching prehistoric phenomenon in the Pan-Pacific region. However, archaeobotanical data examining whether and when early rice farmers occupied these islands is limited and thus contested. Thus, we performed phytolith, OSL and radiocarbon dating analyses of two Neolithic shell mound sites on Haitan Island on the South China Coast. The new dates were amalgamated with the results of earlier absolute dating studies, providing a chronology for these sites. Our results indicate that the two occupation peaks of the Keqiutou Culture centred between approximately 6800-6300 cal BP and 5800-5300 cal BP. Continuous rice phytolith records-including rice bulliforms-were observed in the Neolithic layers at the two sites. Moreover, rice bulliform phytoliths with >= 9 fish-scale decorations accounted for 41%, higher than the established standard for wild rice, suggesting that rice cultivation had already emerged at 6800 cal BP on Haitan Island and probably earlier. These findings provide the earliest evidence of rice cultivation on Haitan Island, adding evidence of the first farmers' sea voyages and colonisation of the South China Coast islands.

In winter, ice is prone to forming on the surface of stay cables in cable-stayed bridges, posing a threat to their structural safety. As temperatures rise, the risk of ice shedding increases, posing a potential hazard to pedestrians and vehicular traffic. At present, de-icing relies mainly on manual operations, which are associated with high safety risks and low efficiency. As a result, the application of robotic systems for stay cable de-icing has become an emerging research focus. A key challenge in robotic de-icing operations lies in the complex and variable surface conditions of ice-covered stay cables, which frequently hinder stable climbing performance. To address this issue, a climbing mechanism was designed, integrating a grooved-track drive and a spring-assisted lead screw clamping system. A fuzzy PID control strategy was implemented to achieve adaptive coordination between the clamping force and climbing speed. Simulink simulations and indoor climbing experiments were performed to verify its effectiveness. The results show that compared with traditional PID control, the fuzzy PID controller reduces the response time by approximately 50%, exhibits better adaptability in icy environments, maintains a climbing speed error within ±1.5%, and improves overall climbing performance.

The southeast coast of China is a crucial area for the spread of agriculture from mainland Asia to Taiwan and the islands of Southeast Asia. However, whether prehistoric rice cultivation in this region was lowland or upland remains unclear. This study used a detailed phytolith analysis to evaluate temporal changes in structure at three coastal sites of varying altitudes in the Fujian Province of China, Longgang, Zhengjiashan, and Gehongshan. Samples were collected from two cultural phases, the Neolithic Huangguashan and Bronze Age Huangtulun cultures. Additionally, a new physical index, the sensitive-to-fixed phytolith ratio, was used to identify the environmental conditions in which crops were cultivated. Using this method, the number of sensitive types can be less or greater than that of fixed types, corresponding to drought or paddy field rice cultivation systems, respectively. The results showed an interplay of rice and millet farming at these sites. The crop phytolith ratio revealed that rice was dominant in the crop structure. However, notable differences existed in the proportion of different crops and phytolith assemblages across the various sites. The sensitive-to-fixed phytolith ratios, indicative of wet-dry environmental changes, were 1.56 and 1.07 at the low-altitude Longgang and water-rich Zhengjiashan sites, respectively, suggesting lowland rice cultivation. In contrast, the sensitive-to-fixed ratio at the high-altitude Gehongshan site was only 0.8, implying upland rice cultivation. The phytolith assemblage variation among the different sites also revealed an increase in dryland crops from low to high altitudes, indicating that the inhabitants of the southeastern coastal mountainous area modified their crop structure and rice cultivation methods during the Neolithic-Bronze Age transition to overcome environmental limitations. In summary, this study presents phytolith evidence for prehistoric upland rice cultivation on the southeast coast of China, offering valuable insights into the development of the prehistoric subsistence economy in the region.

Treacherous driving conditions, especially accumulated snow on roads and bridges, pose a serious safety concern during the winter season. Developing accurate warning systems to classify the severity of snow accumulation in severe weather is crucial. To address this problem, this study investigated the severity of snow accumulation on roads using computer vision techniques. After discussing and analyzing the advantages and disadvantages of the DeepLabV3+ and U-Net models, this paper proposed a classification model for road snow severity based on the fusion of these two models in complex backgrounds. The recognition segmentation task was divided into two stages, with Inverse Perspective Mapping (IPM) added to the output stage of both models. Compared to traditional single-stage models, Pixel Accuracy improved from 76.88% to 97.44%, Mean Intersection over Union from 78.36% to 95.57%, and Class-wise Mean Pixel Accuracy from 79.57% to 96.01%.

This study presents a discrete element investigation on the internal temperature change characteristic and heat transfer efficiency in airport concrete pavement by using the carbon fiber electrothermal method for snow melting and deicing. A discrete element model for snow melting and deicing of airport concrete pavement by using the carbon fiber electrothermal method was generated. The temperature evolution on the surface of the pavement was captured and compared with the indoor experimental results. The numerical simulation results were in good agreement with the experimental results, which verified the applicability of the numerical model. On this basis, the effects of the heating temperature and heating paths on the internal heat conduction and temperature field distribution were investigated. The results showed that the temperature of the pavement surface and the temperature rise gradient are linearly related to the temperature of the carbon fiber heating wire. The initial heating time has little influence on the temperature rise path of the road surface layer after stopping heating and reheating. The temperature of the road surface layer rises slowly after the heating is stopped, and then decreases linearly at a rate of 0.4 °C/h not corresponding to the initial heating time.

The carbon fiber electrothermal method is an efficient approach for snow melting and deicing of pavements in the cold winter. The heat transfer mechanism needs to be explored for the carbon fiber electrothermal system design, especially how the microstructure affects the thermal behavior of pavement. To do so, a discrete element method (DEM) based heat transfer model considering the pavement microstructure has been established in the current study. The shape and content of coarse-grained aggregates have been represented by using the irregular polygonal aggregate method. The accuracy and feasibility of the proposed model were verified by comparing the numerical results with the measured data. On this basis, the heat transfer characteristics of pavements during snow melting and deicing using the carbon fiber electrothermal method have been investigated. The results show that the ambient temperature and the carbon fiber heating wire (CFHW) temperature are the two primary factors affecting the heating efficiency and the maximum temperature on the pavement surface. The spacing and buried depth of the CFHW also play a crucial role in determining the temperature rise rate and the uniformity of temperature distribution of the road surface layer. Furthermore, the effect of the aggregate content on the overall heating rate is not as significant as that of the specific heat capacity ratio of the aggregate to the mortar, suggesting modifying the thermal conductivity of aggregates to enhance deicing efficiency rather than changing the aggregate contents. The effects of the CFHW design parameters on the temperature distribution of the pavement surface are also investigated. The maximum and minimum temperatures of the pavement layer decrease gradually with the increase of the laying spacing and burial depth of the CFHW, but the temperature difference increases with the increase of the laying spacing of the CFHW and decreases with the increase of the burial depth. The research results can provide a reference for the optimization design of snow melting and deicing of pavements by the CFHW heating method.

The identification of stay cable icing is crucial for robot deicing to improve efficiency and prevent damage to stay cables. Therefore, it is significant to identify the areas and degree of icing in the images of stay cables. This study proposed a two-stage model that combines U-Net and ResNet50. In the first stage, this model used U-Net to segment the surface ice and icicles from the stay cable. The image of icing obtained after segmentation was used as the input for the second stage. In the second stage, ResNet50 was used to classify the degree of icing. The experimental results show that the proposed model can successfully segment the icicles and surface ice from the stay cable icing image to complete the classification of the icing degree. The mean pixel accuracy and intersection over the union of icing were 96.65% and 82.10%, respectively. The average accuracy of the icing degree classification was 95.71%. The method proposed in this study meets the requirements of robustness, segmentation accuracy, and classification accuracy for stay cable icing recognition, which provides a research basis for the precise icing recognition of cable-deicing robots.

The ice accumulation on the surface of the stay cable of the bridge is a frequently identified problem that threatens the safety of bridge traffic. Therefore, it is important to investigate the ice accumulation on the stay cable under different conditions. To understand the distribution characteristics and variation rules of ice, this study analyzed the effects of ambient temperature, cable inclination angle, and diameter on the ice accumulation of the high-density polyethylene (HDPE) stay cable. The results show that the ambient temperature significantly affects ice formation in the lower part of the stay cable. Low temperature facilitates the formation and growth of icicles, while larger size and inclination angle of the stay cable inhibit the icicle growth. When the inclination angle of the cable is less than 60°, icicles easily form at the bottom of the cable. Smaller-diameter cables are more likely to accumulate icicles at the bottom.

海湾及近海沉积物中的植硅体组合是恢复河流流域古植被和古环境的有效指标,然而目前对海湾特别是半封闭性海湾沉积物中植硅体的来源和迁移规律的了解还十分有限.通过分析罗源湾表层沉积物的植硅体组合、浓度和不同类型植硅体的分布规律,揭示海湾中植硅体的分布特征及其影响因素.研究表明,罗源湾表层沉积物植硅体浓度存在显著的区域性差异,浓度高值区出现在海湾西北部和中部等沉积环境稳定的区域,东部和南部等水动力较强的区域不利于植硅体沉积.海湾中不同形态的植硅体呈现出特定的分布规律,较小的短鞍型主要分布在沉积环境较为稳定的海湾西北部,而扇型和长方型等较大的植硅体主要分布在海湾中部和东部可门口等水动力较强的区域,河流输入和海湾水动力及其形成的沉积环境可能是影响罗源湾表层植硅体分布的主要因素.海湾植硅体的现代沉积过程研究将有助于提升利用植硅体重建古气候与古环境的准确度.

Electrical heating is an innovative method of preventing icing of bridge decks during winter. Turning on the heating system before snowfall to prevent the icing of the bridge deck is more advantageous than melting already-formed ice. This article analyzes the heat-transfer performance of a bridge deck with heating cables during preheating before snowfall and predicts the preheating time of the bridge deck. Firstly, the temperature rise law and the state of the bridge deck with heating cables were studied through field experiments. Subsequently, a numerical model was developed. The effects of four factors on the heat-transfer performance of the bridge deck were analyzed. Finally, a bridge deck preheating-time model was established based on a multilayer perceptron regressor. This study enriches the application of neural networks and numerical simulations in preventing ice formation using the electrical heating method and is important for optimizing the heating system scheme and saving energy.

The geotechnical properties, chemical reaction mechanisms, and microstructure evolution of alkali-activated fly-ash-stabilised construction and demolition waste (C&D) and the main components recycled concrete aggregate (RCA) and clay brick (CB) were investigated in this study. The alkali activator was a composite solution of sodium hydroxide and water glass. XRD, FTIR, SEM, and UCS testing methods were used to analyse the properties and mechanisms of the alkali-activated fly-ash-stabilised C&D and main single-component RCA and CB. The test results demonstrate that using alkali-activated fly ash in stabilising C&D improves the UCS of the material significantly. When C&D is mixed with fly ash at a mass ratio of 60/40, its UCS reaches 37 MPa at 28 days, which is much higher than the strength requirement of cement-stabilised soil mixture and meets the strength requirements of inorganic binder stable materials for road base and sub-base layers. C-A-S-H and N-A-S-H (where N = Na2O, A = Al2O3, C = CaO, S = SiO2, and H = H2O) generated by the alkaline activation have several similarities with cement hydration products and also show high cementing ability. Alkali-activated fly ash improves the strength and stability of C&D as a roadbed filler and has prospective applications in road engineering.

Phytoliths are an emerging vegetation, environment, and climate proxy used in paleoecology and archaeology. The accuracy of phytoliths as paleo-vegetation and paleo-climate indicators relies heavily on the detailed research on phytoliths extracted from modern plants. For example, Eragrostoideae and Phragmites australis can produce short saddle phytoliths that are similar in shape and size, however, few detailed morphological comparative studies have been conducted on phytoliths.In this study, we described the morphology of short saddle phytoliths produced by stems, leaves, and flower spikes of five species of Eragrostoideae and P. australis. We then measured the lengths and widths of these shorth saddle phytoliths from different parts of the plant. The results showed that most of the short saddle phytoliths were similar in morphology, except for those from the flower spikes of Eragrostis minor, without concave edges. Further detailed differentiation of morphological parameters showed that the average length of the bottom（A） of short saddle phytoliths in the stems and leaves of Eragrostoideae was（11.9 ± 2.3） μm, the average length of saddle（B） was（8.1 ± 1.9） μm, and body width（C） was（12.2 ±2.7） μm. The average length of the bottom（A） of short saddle phytoliths in the stems and leaves of P. australis was（11.9 ±2.2） μm, the average length of saddle（B） was（7.9 ± 1.1） μm, and body width（C） was（11.2 ± 1.6） μm. Morphometric data of short saddle phytoliths of the stems and leaves of Eragrostoideae and P. australis overlapped, and no statistically significant difference existed between them. However, the average length of the bottom（A） of short saddle phytoliths in the flower spikes of E. minor was（8.3 ± 1.0） μm, the average length of saddle（B） was（5.3 ± 1.0） μm, and the average body width（C）was（6.3 ± 1.0） μm, which was much smaller than that of P. australis. Species with these types of short saddle phytoliths were classified into Eragrostoideae. The aim of this study was to explore the differences in short saddle phytoliths from the two subfamilies and to improve their identification in strata or sediments. In addition, this study provides specific references for reconstructing the paleo-vegetation and paleoenvironment of phytoliths.

In cold weather, the outer surface of stay cable sheaths easily freezes. When the ambient temperature increases, the ice on the surface melts easily, and there is a risk of falling ice at high altitudes. In this paper, a simple design method is proposed that uses carbon fiber heating wires to prevent the icing of stay cables. Conventional indoor tests and numerical simulations of heat conduction are carried out for a sheath with a single diameter, and the number of heating wires required for different diameter sheaths is obtained. Taking the stay cable sheath of the Qingshan Bridge in Wuhan as an example, when the diameters of the heating wire and the stay cable sheath are 6 mm and 200 mm, respectively, the temperature rise rule of the heating wire, the calibrated heating power and the convective coefficients are obtained through tests and numerical simulations. At an ambient temperature of 4 °C, thread-like ice formed in the arc range of 0.314 m on the surface of the sheath. The critical non-icing temperature required by the heating wire during preheating to ensure that the sheath surface does not freeze is 1.5 °C.

位于中国东南沿海的福建地区是农业和人口从亚洲大陆向台湾岛及东南亚岛屿等地区传播和迁徙的重要节点, 对其早期农业出现的时间及其与区域环境背景关系研究是理解海岸带古人地关系演变的关键. 文章对位于东南沿海地区闽江下游的大坪顶遗址进行了详细的植硅体分析, 在该遗址文化层堆积物中(约7500cal. a BP)发现了大量来自水稻茎叶的植硅体类型, 并且在其早期遗存的陶片中发现了稻壳印痕和典型的水稻植硅体类型, 指示水稻驯化程度的鱼鳞纹饰≥9个的水稻扇型植硅体占比达到44%, 远高于已经建立的野生稻水稻扇型鱼鳞纹饰标准, 说明早在7500年前后东南沿海地区已经出现了水稻种植, 将东南沿海农业活动开始的时间从距今5000年前推到距今7500年. 对比区域早中全新世海平面与海岸线变迁的历史, 认为东南地区早期水稻种植的出现与中全新世的高海平面和福州盆地的最近一次海侵相关, 高海平面驱使的不断后退的海岸线和海侵形成的“福州湾”可能为北方稻农的南下提供了良好的天然通道.

为了研究砂土宏观应力变形特征与配位数、接触力组构等微观参数的紧密相连性,基于离散元模拟方法开展了砂土等平均应力路径和等小主应力路径真三轴试验,分析了不同应力加载路径下砂土应力-应变关系、体变-应变关系,以及中主应力比(b)对配位数、法向接触力、组构各向异性等砂土微观性能的影响.结果表明:随b值的增大,等小主应力路径下试样峰值应力不断增大,而等平均应力路径下则相反;体积应变均表现为先剪缩后剪胀,且在剪缩阶段b值越大剪缩现象越明显;相同应力比下,沿常规轴对称拉伸的剪切比轴对称压缩诱发的组构各向异性更高;在轴对称拉伸应力路径上,低平均应力下组构各向异性诱导程度更明显;b值对于强偏组构线性关系的斜率几乎没有影响,但随b值的增加,强偏组构峰值减小;2种应力路径下整体强偏组构均随b值的增大而减小,但等平均应力路径下比等小主应力路径下表现更加明显.