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在北方寒冷地区，钢管混凝土结构因冻融作用侵蚀而造成钢管开裂以及钢管混凝土结构力学性能劣化从而导致结构破坏的事故时有发生。针对冻融侵蚀后钢管混凝土界面黏结性能问题，制作了钢管混凝土推出试件，考虑冻融循环次数、混凝土强度、钢管径厚比等不同参数，进行冻融试验和推出试验，分析了界面黏结力的分布规律和影响因素，研究了冻融循环作用后钢管混凝土界面黏结滑移本构关系，确定了界面平均黏结强度以及峰值黏结强度、残余黏结强度特征值。结果表明，随着冻融循环次数的增加，界面平均黏结强度减小，极限荷载对应的滑移逐渐增大，而残余黏结强度呈线性减小，稳定段起点滑移随着冻融循环次数的增加呈指数增长。峰值黏结强度、残余黏结强度随混凝土强度的增加而提高，随着径厚比的增大而降低。分析外钢管密布应变计所测出的应变分布规律可知界面黏结应力呈指数分布，对比分析由荷载、滑移结合能量法理论推导所得的黏结应力分布函数，结果表明其具有较高精度，为后期研究界面黏结性能提供了新思路。构建了冻融循环作用后界面黏结应力-滑移三段式本构模型，并提出了相应特征值计算公式和本构模型，可为该类构件设计时考虑冻融作用提供参考。

随着国内风电行业发展规模日益壮大，风机功率逐渐增大，对下部支撑结构的承载、稳定性能也提出了更高的要求，钢-混凝土混合结构塔筒（上部纯钢塔，下部混凝土塔）应运而生。然而，由于需要现场拼装、灌浆，其建造效率低，后期维护成本高。基于此，提出了一种新型预应力钢管混凝土格构式风电塔架代替原有的钢-混凝土混合结构塔筒。四角柱采用预应力中空夹层钢管混凝土构件，增加刚度的同时减少了钢材和混凝土的用量，方便运输和吊装。中空部分作为预应力孔道进行通长整体张拉，增加结构稳定性及轴向滞回性能。目前，已有一些研究者进行了钢管混凝土构件轴向拉压性能的研究，但鲜少有针对预应力中空夹层钢管混凝土构件轴向复杂受力情况的研究被报道。为了弥补现有研究的不足，针对预应力中空夹层钢管混凝土构件在轴拉、轴压及拉-压滞回受荷状况下的力学性能开展试验研究，为我国制定风电塔架的设计标准提供一定的理论基础和试验依据。

在风电机组预应力钢-混凝土混合结构塔筒中，转接结构是用于连接上部钢塔段与下部混凝土塔段的过渡结构，其受力复杂，采用传统的钢筋混凝土结构形式容易产生裂缝甚至发生破坏。提出了一种中空夹层钢管混凝土转接结构，并进行了4个中空夹层钢管混凝土转接结构试件及1个钢筋混凝土转接结构对比试件的轴压试验。结合有限元及理论分析揭示了中空夹层钢管混凝土转接结构的承载能力及隔板、栓钉等因素对其受力性能的影响。结果表明：在相同用钢量下，中空夹层钢管混凝土结构形式显著提高了转接结构的承载能力及变形能力；隔板和栓钉的设置增强了钢与混凝土的连接，限制了内外钢板的局部屈曲、延缓了混凝土的压溃，进一步提升了结构的轴压受力性能；其中，栓钉对于增强结构整体性更为有利，使结构延性增加更为显著。

为研究钢管混凝土加劲环管板节点在轴向拉力作用下的受力性能，开展了3个节点试件的单调加载试验，分别得到了管板节点加强前后的荷载-位移曲线和破坏模式。试验结果表明：SPR节点在单调荷载作用下主管和加劲环发生局部屈曲，表现为延性破坏；CFT节点在荷载作用下主管壁发生剪切破坏，荷载-位移曲线没有明显的屈服段，表现为脆性破坏；CFTR节点在荷载作用下，连接板处加劲环发生剪切破坏，同时加劲环局部V形屈曲；加劲环能够明显提高管板节点的承载力，同时改善节点的塑性性能；相较于主管外设加劲环，主管内部填充混凝土具有更好的承载力提升效果，节点的刚度变大但塑性性能变差；钢管混凝土加劲环管板节点具有加劲环和混凝土的双重特性，在显著提高节点承载力的同时保障节点塑性性能。在264个有限元模型参数分析的基础上，得到了双加劲环管板节点受拉承载力的计算方法，给出了加劲环厚度和宽度组合的设计建议。基于极限分析的塑性铰线方法，推导出SP节点和SPR节点极限承载力的理论计算模型，计算结果与有限元结果吻合较好。

考虑阻尼器导向装置对锅炉钢结构抗震性能的影响,在SAP2000软件中采用时程分析法分别对未布置阻尼器、布置位移型阻尼器和布置黏滞型阻尼器的1 000 MW锅炉钢结构进行有限元分析,对比锅炉钢结构在地震作用下的底部剪力、顶点位移等结构响应和阻尼器耗能能力,并给出了相应的结构附加阻尼比。结果表明:在6度(0.05g)多遇地震作用下,布置黏滞型阻尼器的锅炉钢结构较布置位移型阻尼器的锅炉钢结构的底部剪力和顶点位移优化效果更佳;位移型阻尼器的耗能效果不佳,为结构附加的阻尼比较小,最大仅为0.004 5,而黏滞型阻尼器充分耗能,为结构附加的阻尼比较大,均在0.071～0.091的范围内,且黏滞型阻尼器为结构附加的阻尼比与地震烈度关系不大;从底部剪力和顶点位移等结构响应、阻尼器耗能能力以及阻尼器为结构附加阻尼比等方面来看,布置黏滞型阻尼器的锅炉钢结构取得的减震优化效果较好,结构抗震性能最优。

结合半潜式和单立柱式海上风机浮式基础的特点,提出了一种用于海上风机的新型钢格构式基础。首先,根据美国可再生能源实验室(National Renewable Energy Laboratory,NREL)提供的5 MW海上风机样机对提出的新型浮式基础进行了结构设计。然后,采用水动力-空气动力-控制系统-系泊系统耦合方法对风-浪联合作用下的新型海上浮式风机的动力响应进行了分析。结果表明:钢格构式浮式基础的纵荡运动主要受风速变化影响,纵摇运动受风速-波浪变化的显著影响,而垂荡运动主要受波浪变化控制。与单立柱式浮式风机相比,钢格构式基础海上浮式风机的纵摇、横摇及艏摇响应更小,具有更好的稳定性,对比结果表明提出的钢格构式浮式基础是一种适用于深海环境下海上风机的新型浮式基础。

结合Spar基础和半潜式基础的浮态稳性特点,提出了一种具有双重抗摇摆机制的浮式风机基础。采用DTU-10MW风机机组参数,对提出的新型浮式风机基础进行了方案设计。基于Morison方程和势流理论,分析了其在不同波浪入射角以及波浪周期下的水动力响应参数,包括运动响应幅值算子和波频力(矩)传递函数等。结果表明提出的浮式风机基础的垂荡、纵摇及横摇固有周期远离典型波浪周期,具有良好的耐波性;除垂向外,各方向的波频力(矩)在高频区较大且变化复杂。与此同时,提出了针对该新型浮式风机基础的水动力性能优化方案,进一步了提高其耐波性和浮态稳定性,使其可以适应不同的海域波浪环境。

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Under the influence of climate change and human activities, significant changes have occurred in the basin water cycle, making the situation for water resources protection increasingly severe. In response to the issues of water shortage in the Yellow River Basin and the difficulty in monitoring terrestrial water storage, this study based on GRACE (Gravity Recovery and Climate Experiment) data and the Variable Infiltration Capacity (VIC) model, estimated the future changes of terrestrial water storage in the Yellow River Basin and analyzed the impact mechanism of climate change on terrestrial water storage. The results show that: a) the changes of terrestrial water storage calculated by GRACE and VIC using the component summation method shows high consistency, effectively simulating the spatiotemporal evolution characteristics of terrestrial water storage in the Yellow River Basin. b) From 2030 to 2100, there is a relatively insignificant increasing trend in terrestrial water storage in the Yellow River Basin, and under the SSP585 scenario, the increasing trend in terrestrial water storage is more intense. c) During the forecast period, precipitation, temperature, and evapotranspiration in various regions of the Yellow River Basin are all projected to increase compared to historical periods. However, runoff in the Yellow River source area and near Lanzhou is expected to decrease compared to historical periods. Although the overall land water storage in the Yellow River Basin shows an increasing trend during the forecast period, only the terrestrial water storage anomaly in Inner Mongolia is greater than 0. [ABSTRACT FROM AUTHOR]

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【 Objective/Meaning】 In view of the problems and pain points of grain logistics and reserves in Fujian, the countermeasures and suggestions for the digital grain logistics system in Fujian Province were put forward, in order to provide reference for optimizing the digital grain logistics system in Fujian and effectively shoulder the heavy task of ensuring the food security. 【Methods/Procedures】Through the analysis of the grain demand and logistics status in Fujian Province, the problems of supply chain, informatization, standardization and infrastructure in the development course of digital grain logistics system in Fujian Province were explored. 【Results/Conclusions】In order to promote the high-quality transformation and upgrading of the grain logistics system in Fujian Province, from the four aspects of “ collection”, “ transformation”, “ intelligence” and “integration”, the countermeasures were put forward including strengthening the overall awareness of logistics by constructing the food supply chain network; realizing the intelligent and efficient operation by attaching importance to the construction of standard system; strengthening the digitalization level of grain storage by doing a good job in the infrastructure of intelligent logistics;and building the grain logistics information platform by integrating the development of logistics and information, thus to promote the high-quality transformation and upgrading of the grain logistics system in Fujian Province. [ABSTRACT FROM AUTHOR]

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Rapid and accurate prediction of digital currency transactions is of great significance to deal with transaction risks and promote transactions, the bitcoin transaction can be modeled as a dynamic network with continuous time characteristics by using the user evaluation of bitcoin transaction, and the transaction prediction can be transformed into a link prediction problem of dynamic network. The graph neural network method can learn the existing information in the transaction network, get the embedding of each user, and finally use the embedding to calculate the probability of possible link between users to achieve the transaction prediction. In order to predict bitcoin transactions more effectively and to solve the problem that existing graph neural network methods ignore the importance of timely feedback of new information generated in the network, which makes it difficult to accurately predict bitcoin transactions, this paper proposes a new model based on graph neural networks for bitcoin transaction prediction, which aggregates user’s neighborhood information through time attention mechanism and introduces a novel information feedback mechanism to make full use of network information. Experiments on two real data sets show that the improved model is about 7%, 6% and 22% higher than the best comparison model under AUC, AP and F1 indexes, respectively, and can make more accurate analysis and prediction of bitcoin transactions. [ABSTRACT FROM AUTHOR]

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