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通过一维粒子模拟研究了利用相对论少周期强激光与固体密度等离子体表面相互作用实现单个孤立阿秒光脉冲产生的参数条件。主要研究描述相互作用的多维参数，如激光强度、入射角和等离子体标尺长度等，对相对论高次谐波能量转换效率和孤立阿秒光脉冲分离度的影响。研究发现，虽然激光等离子体参数对阿秒光脉冲产生的影响是复杂的，但是存在着能够实现大能量孤立阿秒光脉冲的最佳等离子体标尺长度和最佳入射角。当其他相互作用条件确定时，使用中等强度的相对论强激光可以在较宽的参数范围内实现孤立的阿秒光脉冲。大角度入射时，孤立阿秒光脉冲的分离度较高，能够实现孤立阿秒光脉冲的相互作用参数范围也较宽。The generation of single isolated attosecond light pulses from the interaction of relativistic few-cycle lasers with solid density plasma surfaces is investigated using one dimensional particle-in-cell simulations. The primary subject of the study is the effects of the multi-parameter combinations which uniquely define the laser plasma interactions, on the laser to relativistic high-order harmonic energy conversion efficiencies, and also on the single attosecond light pulse isolation degrees. Here these multi-parameters include laser intensities, incidence angles, plasma scale lengths, etc. The impact of laser-plasma interaction parameters on attosecond light pulse generations is generally complicated. However, there exist an optimal plasma scale length and an optimal incidence angle to efficiently generate high-order harmonics and intense attosecond light pulses. When other parameters are fixed, a moderately intense relativistic laser is more advantageous to realize isolated attosecond light pulses with a broad controlling parameters range. And a larger incidence angle favors a higher isolation degree as well as a broader range of controlling parameters towards the generation of intense isolated attosecond light pulses. Copyright © 2022 High Power Laser and Particle Beams. All rights reserved.

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The health of a river ecosystem is the foundation of the sustainable development of a basin, while the natural variability of the hydrological regime is a key factor for maintaining and protecting the ecological health of a river. Therefore, variation attribution of the hydrological regime in the changing environment becomes more important. In this study, the Laohahe basin was selected as a case study area and its hydro-meteorological data during 1964-2016 were collected to achieve the study aim. Firstly, the study period was divided according to the trend and change points test results of Mann-Kendall, Pettitt and precipitation-streamflow double cumulative curve method. Then, the natural streamflow series was reconstructed using the Variable Infiltration Capacity (VIC) model. After that, the principal component analysis (PCA) was used to select the most ecologically relevant hydrological indicators (ERHIs). Then the degree of the change of the hydrological indicators was evaluated by the range of variability approach. Finally, the ' simulated-observed' comparison method was adapted to quantify the impacts of climate change and human activities on the variations of streamflow and ERHIs. The results showed that the annual streamflow series of the basin had a significant downward trend (α < 0.05) and its change points appeared in 1979 and 1999, respectively. Then the whole study period could be divided into base period, changed period I and II based on the above two change points. Then, 7 ERHIs were selected, including February flow, June flow, annual maximum 7-day flow, Julian day of each annual 1-day minimum, number of low pulse each year, mean duration of high pulse within each year, and rise rate. The 6 ERHIs, February flow, June flow, annual maximum 7-day flow, number of low pulse each year, mean duration of high pulse within each year, and rise rate, had a downward trend. While the Julian day of each annual 1-day minimum showed a slight upward trend. Also, the comprehensive degree of change of the 7 ERHIs ...

碰撞是在自然、生活、运动和工程中广泛存在的力学现象。在简要回顾研究历史之后，本文概述了物体对心正碰撞的基本力学规律；同时指出理论力学的动力学部分提供的理论工具仅限于动量守恒和动量–冲量定理，对撞击力、撞击脉冲和能量损失这些重要的力学量均不能给出任何信息。接着介绍了在线弹性力学、接触力学和弹塑性力学等不同框架下对碰撞问题建立的力学模型，强调碰撞之后的恢复系数并不是材料常数，它同撞击速度密切相关。文章最后呼吁在力学基础教学改革中要弥补碰撞力学知识，帮助学生树立正确的概念。Collision is a kind of mechanical phenomena which widely exist in nature, people’s live, sports and engineering. After a brief review of historical development, the article summarizes the fundamental laws of collinear collision between two particles/bodies, and points out that the particle dynamics only provides us the law of momentum conservation and the momentum-impulse theorem, with no information on the magnitude and pulse shape of colliding force, or on energy loss during collision. The mechanical models of collision based on linear elasticity, contact mechanics and elastoplastic theory are respectively illustrated, indicating that the coefficient of restitution (COR) is not a material constant. Finally, the article calls for making up the knowledge of collision dynamics in the teaching reform of basic mechanics, so as to help students to establish correct concepts. © 2022, Chinese Academy of Mechanics. All rights reserved.

林伯强，厦门大学管理学院中国能源政策研究院教授、博士生导师，长江学者特聘教授，经济学博士；王喜枝,厦门大学管理学院中国能源政策研究院研究助理；杜之利，厦门大学管理学院中国能源政策研究院助理教授，经济学博士。 ; 【中文摘要】中国工业发展初期沿用高能耗、高排放、低效率的粗放型经济模式造成一系列环境问题,提高能源效率是解决当前环境污染与能源短缺双重困境、实现碳达峰与碳中和的必然选择。环境污染的负外部性催生了政府环境规制。现有理论分析表明，环境规制通过成本效应和技术创新作用于能源效率，但相关研究多集中于考察地区特征对能源效率的影口向,可宏观数据往往会忽略企业异质性的影响。基于2003—2011年中国工业企业能源环境数据，可考察环境规制对企业能源效率的影响及传导机制。研究结果表明：中国工业能源效率存在发展不平衡现象。环境规制通过增加污染末端治理成本和倒逼技术创新对工业能源效率产生正向影响。同时,环境规制对能源效率的影响存在异质1性：由于存在污染避难所效应，环境规制对重度污染企业的能源效率影响并不明显，并且对高资源禀赋地区的能源效率具有更明显的改善作用。 【Abstract】The extensive economic model with high energy consumption，high emission and low efficiency adopted in the early stage of China's industrial development caused a series of environmental problems. Improving energy efficiency is an inevitable choice to solve the dilemma between energy shortage and environmental pollution and to achieve peak carbon dioxide emissions and carbon neutrality. The negative externality of environmental pollution has given birth to government environmental regulation. The existing theoretical analysis shows that environmental regulation can affect energy efficiency through cost effect and technological innovation，but it only focuses on the impact of regional characteristics on energy efficiency by using macro data which neglects the impact of enterprise heterogeneity. Based on the energy and environmental data of Chinese industrial enterprises from 2003 to 2011，the impact of environmental regulation on enterprise energy efficiency and its transmission mechanism was investigated. The results show that there is an imbalance of industrial energy efficiency in China. Environmental regulation can positively afect Chinese industrial energy efficiency by increasing the cost of environment pollution end treatment and driving technological innovation. The impact of environmental regulation on energy efficiency is heterogeneous. Larger-scale enterprises are more sensitive to environmental regulation. The impact of environmental regulation on energy efficiency of heavily polluting enterprises is not obvious due to the existence of a certain “pollution haven effect”. And it can dramatically improve the energy efficiency in high resource endowment areas. ; 中央高校基本科研业务费专项资金资助项目“汽车能源消费核算指标体系设计”（20720201023)

目前铂（Pt）及其合金仍是氢燃料电池首选催化剂，但是Pt高价格、低储量及循环稳定性差等缺点严重阻 碍了氢燃料电池商业化，因此发展低成本、高性能的新型非Pt催化剂和低Pt催化剂是实现氢燃料电池商业化的 关键。本文围绕燃料电池催化开发及使用过程中存在的成本、稳定性和毒化问题，回顾了近年来阴离子交换膜燃 料电池和质子交换膜燃料电池催化剂分别在提高阳极催化剂活性、降低阴极催化剂成本领域的最新研究进展，包 括催化剂的组成、结构以及颗粒尺寸等对催化活性、稳定性的影响。最后针对燃料电池催化剂存在的问题，指出 未来应基于原位观测和表征技术加强对碱性氢氧化机理的研究，同时开发高温制备小尺寸高有序度的有序铂合金 阴极催化剂的方法是未来的研究重点。 Currently, the carbon supported Pt and Pt alloy nanoparticles (NPs) are still the primary electrocatalysts for hydrogen fuel cells. However, the large-scale commercialization of hydrogen fuel cells is impeded due to the poor durability, high cost and low reserves of Pt. Hence, the development of low-cost, high-performance non-Pt or low-Pt electrocatalysts is a key for the commercialization of hydrogen fuel cells. With the focus on the cost, durability and poisoning of electrocatalysts, this paper reviews the latest research progress in improving the activity of anode catalysts and reducing the cost of cathode catalysts. Moreover, this paper also summarizes the influence of the composition, structure and size of nanoparticles on the activity and durability of the catalysts. Finally, we provide guidance for the development of fuel cell catalysts, that is, the application of in-situ characterization techniques to unravel the hydroxide (HOR) mechanism in alkaline medium, and the development of facile and efficient strategies to fabricate the small size and highly order intermetallic Pt alloys catalysts. © 2021, Chemical Industry Press Co., Ltd. All right reserved.

李江龙，西安交通大学经济与金融学院教授、博士生导师，经济学博士；杨秀汪，西安交通大学经济与金融学院博士研究生。 ; 【中文摘要】作为世界最大的能源消费国，“新常态”下的中国正处于全面开展环境治理的承重期。在此背景下,聚焦“新常态”视角，采用IDA-PDA分解，可探究中国能源需求变化背后的驱动因素。研究发现:经济增长依旧是中国当下能源需求增长最重要的推力，而且西部地区显著强于东、中部地区;要素替代、经济结构和能源结构变化都抑制了能源需求增长。对于中国绿色转型可能的挑战是，技术进步对能源需求的抑制作用正在减S技术效率甚至存在出现恶化的风险。 【Abstract】As the largest energy consumer worldwide，China in the “new normal era” is striving for environmental improvement. Within this context，this paper pays close speical to the “new normal era”，using the IDA-PDA method to explore the driving forces behind China's energy consumption change. We found that economic growth remains the most important factor driving energy consumption increase，which is even more substantial in western China. Furthermore，input substitution，economic and energy structure have negative impacts on energy consumption. We highlight that the potential challenge to China's green transition lies in the decreasing effect of technological progress and declining energy efficiency. ; 国家自然科学基金青年项目“低效’能源孙贴动态测度及其退出对中国绿色经济增长转型的作用机理研究”（71703120);中国博士后基金特别资助项目“从‘诅咒’到‘福音’：资源型城市的绿色经济增长转型” (2018T111027)

為了研究重復沖擊載荷作用下泡沫金屬夾芯梁的動態響應,采用Abaqus數值仿真軟件,基于可壓碎泡沫模型（crushable foam）,建立了泡沫金屬夾芯梁遭受楔形質量塊沖擊的有限元模型。通過將仿真獲得的夾芯梁上下面板最終撓度與重復沖擊實驗結果進行對比,驗證仿真方法的準確性。在此基礎之上,分析了泡沫金屬夾芯梁在楔形質量塊重復沖擊作用下的變形模式、加卸載過程以及能量耗散特性。結果表明,在重復沖擊載荷作用下,夾芯梁的變形不斷累積,上面板主要出現局部凹陷和整體彎曲,而芯層則是局部壓縮,下面板表現為整體彎曲。在重復加卸載過程中,加卸載剛度隨著沖擊次數的增加而增大。隨著沖擊次數的增加,上面板和芯層的能量吸收增量不斷減小,而下面板的能量吸收增量不斷增加,且最終均趨于穩定。泡沫金屬夾芯梁的塑性變形能增量不斷減小,而回彈系數隨著沖擊次數逐漸增加,最后趨于穩定值。 The phenomena of repeated impacts are very common, especial in the field of ship and ocean engineering. When the ship structures suffering from repeated impact loadings, the deformation and damages will accumulate, leading to failure even damage of the structures, which may cause serious accident. In order to study the dynamic behaviors of metal foam sandwich beams (MFSBs) under repeated impact loadings, the nonlinear finite element model was established based on the material model of crushable foam by using Abaqus-Explicit, and the approach to achieve repeated impacts in the software was proposed. The accuracy of the numerical simulation was verified by comparing the permanent deflections of front and back face sheets. Based on the results of the numerical simulations, the deformation modes, loading and unloading process as well as the energy absorption behavior of the MFSBs under repeated impacts were analyzed. Results show that during repeated impacts, the deformation of the MFSBs is accumulated gradually, the front face sheet mainly experiences global bending and local indentation, and the metal foam core suffers from local compression, while the back face sheet is subjected to global bending. During the repeated impacts, the loading and unloading stiffness increases with the impact number. The energy absorption of front face is larger than that of back face and metal foam core in all the impacts. As the impact number increases, the energy absorbed by front face sheet and foam core declines gradually, while that of the back face sheet increases, approaching a constant value. The plastic deformation energy of the MFSBs decreases with the impact number, on the opposite, the rebound energy of the MFSBs increases gradually with the impact number, while both of them trends to be stable. The proposed finite element method can be applied to accurately predict the dynamic responses of the MFSBs suffering from repeated impact loadings, and provide technical supports for the anti-impact design of metal foam sandwich structures. © 2021, Editorial Staff of EXPLOSION AND SHOCK WAVES. All right reserved.

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Author name used in this publication: 刘明 ; Title in Traditional Chinese: 語料庫輔助的中國生態形像建構研究 ; 202305 bcch ; Version of Record ; RGC ; Published