Cosmic rays and particle physics at extremely high energies

Cosmic ray extensive air shower observations can give clues about the properties of high-energy particle interactions above 10¹⁵eV, in addition to giving information about the primary cosmic ray spectrum at these energies. A brief review of recent high energy accelerator data and its theoretical interpretation is given to explain the necessity for obtaining information from cosmic rays about hadronic interactions beyond machine energies. In particular, it is shown that recent measurements of the energy dependence of total cross-sections and of production cross-sections suggest some sort of threshold behavior in the 1000 GeV region. Studies at higher energies are required to understand the nature of this behavior. The use of air shower data for this purpose is illustrated by comparing shower size us depth measurements with the expectations of various models of strong interactions.     

甲基丁烯醇的光电离实验与理论研究

利用同步辐射光电离质谱的方法研究了甲基丁烯醇(C5H10O)在9.0～15.5eV的真空紫外光电离和光解离过程.通过测量光电离效率曲线,得到了C5H10O的电离能和主要碎片离子的出现势.通过对实验和计算结果的比较,分析了母体离子可能的光电离解离机理.母体离子的解离通道可以分为2类:由C5H10O+直接发生键断裂的解离和经由过渡态的解离.确定了C4H 5+和C3H 5+离子的过渡态和中间体,其反应势垒与实验解离能是符合的.     

丙烯酸甲酯的真空紫外光电离质谱研究

利用同步辐射光和反射飞行时间质谱,研究了丙烯酸甲酯9.0~15.5 eV能量范围的真空紫外光电离和光解离.实验测量丙烯酸甲酯的光电离质谱和解离碎片离子m/e=86(C4H6O+2), 85(C4H5O+2), 59(C2H3O+2), 58(C3H6O+), 55(C3H3O+), 42(C3H+6), 31(CH3O+), 27(C2H+3), 和15(CH+3)的光电离效率曲线.并利用量子化学从头算(G3),计算碎片离子的能级,推测它们的解离通道.计算的电离能和出现势与实验结果符合很好.结果表明,丙烯酸甲酯的光电离解离通道以单键断裂反应为主.     

中国节能政策的经济增长效应与最优节能路径选择

本文设计了两种节能政策(固定额度的节能政策和比例额度的节能政策),并利用中国各省1995-2011年的省际面板数据,根据加入能源消费的扩展Cobb-Douglas生产函数,运用时间可替代DEA模型分析了在不同节能目标(54.4%,68%,90.5%,20%节能额度)约束下,中国这两种节能政策的经济增长效应和最优路径,并讨论了全要素生产率对潜在经济增长损失率及最优节能路径的影响。本文的研究结论表明比例额度的节能政策实施效果更好,节能目标的制定应充分考虑各省的实际情况,生产率较高的省份在较高节能目标的约束下产出损失更大,而生产率较低的省份实施节能政策反而有利于经济增长。本文的结论只能部分支持节能和经济发展双赢的环境波特假说,对于有的省份而言节能和经济增长之间还是面临着两难抉择。     

全面建设小康社会的能源合理利用与CO2减排

与世界发达国家的比较,可以发现中国能源消费结构以煤为主,CO2排放总量大但人均量小,单位能耗的CO2排放指标偏高.21世纪头20年是中国全面建设小康社会的关键时期,在人口将继续增长、能耗规模继续增大、以煤为主的能源结构难以根本改变的情况下,如何实现CO2减排,是对中国的严峻挑战.借鉴发达国家的经验教训,该文提出优化产业结构,不断提高新技术产业和第三产业的比例;改善能源结构,提高水电、核能、太阳能及生物能等清洁能源比例;引进和开发能源环保技术,提高能源利用效率;以法律、政策和经济手段,促进能源合理利用和削减CO2的排放量的设想和对策.     

New projects in particle physics

Recent results in the field of particle physics raise many questions on the elementary constituents of matter and their interactions. These cannot be answered, nor the latest theoretical predictions verified, without accelerators operating at higher energies. Pending world-wide collaboration for the construction of a gigantic accelerator, individual nations are engaged in an increasingly competitive race to construct such machines. The author describes the main assemblies under construction or currently planned in Western Europe, the USA and the USSR, and discusses the technical, financial, political, and, by no means least, human problems involved.     

Coulomb excitation of atomic electrons in heavy ion—atom collisions

The relationship between Coulomb excitation of collective nuclear levels and Coulomb ionization of atomic electrons is discussed. Particular emphasis is placed on K shell ionization in this paper. Results of initial experiments with the Triangle Universities Laboratory Cyclo-Graaff where K X-ray production cross-sections were measured for Ca, Ti and Ni are given. The energies at which these cross-sections reach a maximum value were found and agreed well with theory. The experimental cross-sections had the same trend with energy as the theory but were too high by typically 25 per cent. Reasons for this disagreement are discussed. A similar experiment is described where Ag was the target. In this case theory and experiment agreed quite well. An experiment is described where Bi is bombarded with protons from 2–15 MeV and the K X-ray production cross-sections are measured. Also Po K X-rays are detected at the higher bombarding energies and it is shown that Coulomb ionization cannot be responsible. The most likely process for production of these X-rays is internal conversion of excited reaction products following (p, n) and (p, 2n) reactions.     

Elasto-inertial particle focusing under the viscoelastic flow of DNA solution in a square channel

Particle focusing is an essential step in a wide range of applications such as cell counting and sorting. Recently, viscoelastic particle focusing, which exploits the spatially non-uniform viscoelastic properties of a polymer solution under Poiseuille flow, has attracted much attention because the particles are focused along the channel centerline without any external force. Lateral particle migration in polymer solutions in square channels has been studied due to its practical importance in lab-on-a-chip applications. However, there are still many questions about how the rheological properties of the medium alter the equilibrium particle positions and about the flow rate ranges for particle focusing. In this study, we investigated lateral particle migration in a viscoelastic flow of DNA solution in a square microchannel. The elastic property is relevant due to the long relaxation time of a DNA molecule, even when the DNA concentration is extremely low. Further, the shear viscosity of the solution is essentially constant irrespective of shear rate. Our current results demonstrate that the particles migrate toward the channel centerline and the four corners of a square channel in the dilute DNA solution when the inertia is negligible (elasticity-dominant flow). As the flow rate increases, the multiple equilibrium particle positions are reduced to a single file along the channel centerline, due to the elasto-inertial particle focusing mechanism. The current results support that elasto-inertial particle focusing mechanism is a universal phenomenon in a viscoelastic fluid with constant shear viscosity (Boger fluid). Also, the effective flow rate ranges for three-dimensional particle focusing in the DNA solution were significantly higher and wider than those for the previous synthetic polymer solution case, which facilitates high throughput analysis of particulate systems. In addition, we demonstrated that the DNA solution can be applied to focus a wide range of particle sizes in a single channel and also align red blood cells without any significant deformation.     

基于CGE和EFA的中国能源使用安全测度

全球生态环境的日益恶化和能源使用对环境产生的巨大影响使能源使用安全问题受到各国的广泛关注。鉴于经济、社会、能源和环境的复杂关系,本文在拓展可计量均衡模型（CGE）原有研究的基础上,借助生态足迹分析法（EFA）的概念,构建能源CGE模型和能源使用安全测度框架,将能源的最终需求、初始能源转换矩阵、能源生态足迹转换率和本区域的能源生态承栽力联系在一起,通过对比能源生态承栽力和生态足迹,分析能源使用安全状况。对中国1962年至2002年能源使用安全测度,结果显示,这40多年里,从人均和总量水平来看,能源生态承载力基本呈逐年下降趋势,而能源生态足迹呈逐年上升趋势,并且,能源人均生态承载力的下降速度快于能源人均生态足迹的上升速度,最终造成能源生态赤字的出现及不断扩大的演变规律,说明我国能源使用安全状况越来越令人担忧。要扭转这种不利的发展态势,也应该从能源使用的环境影响和环境容量两个方面入手,期望通过逐步减少能源使用的环境影响和提高环境质量,全方位加强我国的能源使用安全。     

New physics searches at the BESIII experiment

The standard model (SM) of particle physics, comprised of the unified electroweak and quantum chromodynamic theories, accurately explains almost all experimental results related to the micro-world, and has made a number of predictions for previously unseen particles, most notably the Higgs scalar boson, that were subsequently discovered. As a result, the SM is currently universally accepted as the theory of the fundamental particles and their interactions. However, in spite of its numerous successes, the SM has a number of apparent shortcomings, including: many free parameters that must be supplied by experimental measurements; no mechanism to produce the dominance of matter over antimatter in the universe; and no explanations for gravity, the dark matter in the universe, neutrino masses, the number of particle generations, etc. Because of these shortcomings, there is considerable incentive to search for evidence for new, non-SM physics phenomena that might provide important clues about what a new, beyond the SM theory (BSM) might look like. Although the center-of-mass energies that BESIII can access are far below the energy frontier, searches for new, BSM physics are an important component of its research program. This report reviews some of the highlights from BESIII’s searches for signs of new, BSM physics by: measuring rates for processes that the SM predicts to be forbidden or very rare; searching for non-SM particles such as dark photons; performing precision tests of SM predictions; and looking for violations of the discrete symmetries C and CP in processes for which the SM expectations are immeasurably small.     

金刚石/铜复合材料传热数值模拟

本文采用有限元方法对金刚石/铜复合材料的传热性进行数值模拟,建立多颗粒二维随机分布复合材料测试模型,研究金刚石颗粒体积分数、颗粒半径、颗粒形貌、粒径比及界面因素对金刚石/铜复合材料传热性能的影响规律及机制。结果表明:金刚石/铜复合材料的热导率随着金刚石体积分数的增大而升高;热导率随着粒径的增大而呈现先升高后降低的规律;方形金刚石颗粒的复合材料热导率高于球形颗粒的复合材料;在金刚石体积分数一定时,适量配比细颗粒可提高材料热导率;对金刚石表面镀覆层新物质(W、Cr、Ti)来等效金刚石和铜二者物理结合时的界面热阻。     

基于G8与BRIC的新能源及可再生能源发电绩效动态评价

新能源及可再生能源发电是各国能源可持续发展战略的重要组成部分.本文针对各种新能源及可再生能源的特点,对各国新能源及可再生能源的潜在资源量予以定义和整理,以此为基础提出新能源及可再生能源发电绩效指数(REPPI),对八国集团和金砖四国从2000年-2008年的新能源及可再生能源发电绩效进行动态评价.之后,使用面板数据模型对新能源及可再生能源发电绩效与宏观经济条件、技术进步、电力消费和R&D投入之间的关系进行分析,研究了各国新能源及可再生能源发电绩效的驱动力.结果表明:发达国家的REPPI普遍高于发展中国家,但REPPI的增长速度却低于发展中国家.新能源及可再生能源资源量丰富的国家,REPPI普遍低于新能源及可再生能源资源量匮乏的国家;技术进步和新能源及可再生能源R&D投入比重在推动REPPI提高方面具有显著作用.最后,给出了促进我国新能源及可再生能源电力发展的政策建议.     

中国风电和碳捕集技术发展路径与减排成本研究——基于技术学习曲线的分析

煤炭是我国能源的主体,煤电也是我国电力的主要构成。我国未来低碳发展将主要取决于低碳电力技术的选择及其推广,其中风电与碳捕集与碳封存(CCS)技术发展十分迅速但都处于发展初期,其未来不确定性较大。本文将基于风电和碳捕集的技术学习曲线,探讨这两类技术未来发展的主要问题,包括(实现市场竞争所需的)推广时间、减排潜力和减排成本等,以期为政策制定者提供参考。研究发现：在减排量与发展路径相同的前提下,风电技术成本较新建煤粉(PC)电厂碳捕集技术成本略高,后者若考虑了碳运输与碳封存成本在内,其减排成本将更高;另外,考虑了技术学习效应后,风电技术与CCS技术成本较相关研究结果都更低。到2025年风电技术发展将面临电网基础设施的瓶颈,在当前技术条件下将很难取得突破;碳捕集技术减排潜力更大,其新增投资主要表现在燃料成本与新增资本投资部分,当前主要工作应加快发展碳捕集示范项目、强化国际学习与合作,降低其不确定性,在2025年实现CCS与风电技术的对接。     

鹤山乡土混交林的能量特征及光能利用率

通过对鹤山以红荷和荷木为主的乡土树种混交林的辐射能、光合呼吸作用与总第一性生产力、生物量与热值等的综合研究可知：１全年抵达该群落林冠上层的总太阳辐射能４５１５．２ＭＪ·ｍ－２，截获２５１９．３ＭＪ·ｍ－２，透过１４７２．２ｍＪ·ｍ－２；２群落总的生物量１０３．３１ｔ；能量现存量１７１．３３ＭＪ·ｍ－２；３群落冠层截获能量中有８６．８０ＭＪ·ｍ－２用于光合作用，其中有２１．７１ＭＪ·ｍ－２用于净第一性生产力；其光能利用效率约０．４８％；４由于群落年龄和冠层结构原因，鹤山乡土树种混交林群落的生物量现存量、净第一性生产力和光能截获率均低于同地带近顶极群落一季风常绿阔叶林的相应值．     

A particle inerter system for structural seismic response mitigation

This study introduces a novel particle inerter system (PIS) designed for vibration mitigation of structures. The new system comprises an inerter subsystem, a spring, and a tuned particle element, where the spring is used for tuning the particle element and the inerter subsystem is set for energy absorption and dissipation. The structural performance and the vibration mitigation effect of the PIS are assessed in terms of displacement and acceleration responses. An optimal design method is developed for a PIS under a performance-oriented design framework. Following the criterion of lightweight control, the added mass of the PIS is minimized under the constraints of target displacement and acceleration responses. A parametric analysis is performed and the robustness of the PIS for seismic response mitigation is verified. Design cases are carried out for the illustration of the proposed design method. The results show that the structural displacement and acceleration responses can be reduced significantly with the help of a PIS. Compared with the particle tuned mass damper with the same parameters, both the energy absorption and dissipation effects of the PIS are increased and the relative displacement response of the container in the PIS is reduced by the inerter subsystem. Under the same performance target, the required physical mass of the container and particles in the PIS is minimized and is significantly smaller than that of the conventional particle tuned mass damper.     

自然保护区周边社区薪柴消费影响因素分析

薪柴作为一种传统能源,依然是自然保护区周边社区的主要生活能源。落后的薪柴采集和消费不仅造成能源浪费,还严重影响着自然保护区的资源生态环境,因此促进自然保护区周边社区的薪柴消费向高效清洁的商品能源消费转变具有重要意义。本研究基于陕西省洋县和宁陕县朱鹮自然保护区周边社区农户薪柴消费微观调查数据,采用多元线性回归模型,对自然保护区周边家庭薪柴消费的影响因素进行了计量分析。结果表明,0.01的显著水平上,家庭人口数、家庭年龄、养殖业收入对农户薪柴消费具有显著正向影响,外出务工收入对农户薪柴消费具有显著反向影响;在0.05的显著水平上,个体经营收入对农户薪柴消费具有显著反向影响。因此,通过提高农民的教育水平,引导农村剩余劳动力进城务工,加强自然保护区转移支付等方式,促进自然保护区周边能源消费从薪柴消费向商品能源消费转变,是解决自然保护区周边社区森林资源破坏的有效途径。     

基于LEAP的城市居住区能值评价与复合情景分析

中国城市化正呈现快速发展的态势,但支撑和驱动这种态势是资源的大量消耗。由于上游产品工艺相对落后、加工效率较低、下游消费格局有待改善等原因,使得当前中国城市发展中的能源环境的可持续性面临巨大挑战。以城市居住区为研究案例,结合LEAP模拟平台,对小区的能源和原材料消耗终端进行了自底向上的系统建模,并结合能值评价指标及多情景的复合分析评估了小区的生态压力、服务及整体可持续性水平,并对常规发展趋势和当前可行的改进措施进行了定量化研究与比较。结果表明,未来常规情景下案例社区的能值可持续性将大幅度下降,应用改进措施在一定程度上能缓解恶化情况,其中提高终端设备效率的技术方案效果较好。但彻底提升城市居住区的可持续性还有待进一步的研究与探讨。     

资源经济贡献与发展诅咒的互逆关系研究——中国31个省区能源开发利用与经济增长关系的实证分析

资源是经济发展的物质基础,经济的发展离不开资源支持;然而,在知识经济时代和不公平的贸易下,自然资源禀赋及生产量大的地区,往往经济比较落后,呈现出"资源诅咒"现象。本文选取1985年~2004年中国各省区经济发展及能源生产/消耗的相关数据,从资源经济贡献和发展诅咒两方面进行实证研究,结果显示:经济总量大、增长速度快的省区,能源消耗量亦较大,反之,能耗就较低;能源储量丰富、生产量大的地区,往往经济发展水平及增长速度都较低,出现了"富饶的贫穷"。汇总这两方面研究,本文绘制了能源产耗和经济发展的矩阵图,将中国31个省区划分为不同类型:上海、浙江、北京等东部沿海省区,生产量最低、能源消耗量较高,经济发展水平居于我国领先地位;山西、内蒙古、陕西等中西部地区,能源生产量大、消耗量相对较低,经济发展水平比较落后;另外,河南、四川、江西等省区产耗相当,经济发展水平也随之同步变化。     

中国知网居前1‰高被引论文的学科阈值

寻找各学科居前1‰高被引论文的阈值,是评估科研绩效的标尺。利用中国知网检索了94个学科领域的居前1‰高被引论文,对被引用阈值和权重进行排序,发现各学科领域的阈值严重不均衡,最高值和最低值之间相差55倍,平均阈值为101。各学科阈值的高低取决于以下因素:文献总量多的学科领域高于文献总量少的学科领域;哲学与人文社会科学同一学科内基础理论领域高于其他领域等。