Flow Regimes in Bubble Columns with and without Internals: A Review

Hydrodynamics characterization in terms offlow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies.This review presents recent studies on the typicalflow regimes established in bubble columns.Some effort is also provided to introduce relevant definitions pertaining to thisfield,namely,that of“void fraction”and related(local,chordal,cross-sectional and volumetric)variants.Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail.In the second part of the review,the attention is shifted to cases with internals of various types(perfo-rated plates,baffles,vibrating helical springs,mixers,and heat exchanger tubes)immersed in the bubble columns.It is shown that the presence of these elements has a limited influence on the global column hydrodynamics.However,they can make the homogeneousflow regime more stable in terms of transition gas velocity and transi-tion holdup value.The last section is used to highlight gaps which have not beenfilled yet and future directions of investigation.

Modelling the Iranian Petroleum Contract fiscal regime using bargaining game theory to guide contract negotiators

Based on Iran's sixth development plan,the country's oil and gas industry requires an investment of about$200 bn in the next five years to increase production.The Iranian government,to attract and motivate international oil company investment in their oil and gas fields,has presented a new type of risk service contract:the Iranian Petroleum Contract(IPC).This paper summarizes the features of the IPC and presents mathematical models of its fiscal regime for the benefit and guidance of both the National Iranian Oil Company(NIOC)and the contractors.Next,adopting bargaining game theory provides a mathematical model for reaching a win-win situation between the NIOC and the contractor.Finally,a numerical example is given and a sensitivity analysis performed to illustrate the implementation of the proposed models.The contractor and the NIOC may use these models when preparing their proposal and in the course of actual negotiations to calculate their internal rate of return,remuneration fee,and net present value for developing the fields at different conditions of their bargaining power,and derive a logical bargain to protect their best possible interests.

Essence and resolution of international climate negotiation

In essence, international climate negotiation is a serious and responsible global effort, despite various conflicts, to establish a rational international climate regime. In essence, tackling climate changes is leading the globe to actualize sustainable development of all humankind along the low-carbon, green, and cyclic-development path. Thus, climate negotiation should be driving all parties to achieve a global climate regime arrangement in a constructive way. Therefore, this paper suggests focusing on the following three major recommendations: early developed countries take the lead in committing positively to absolute emission reduction; the developing countries contribute according to their abilities and stages of development; the developed countries perform real deeds using their funds and technology. Based on substantial breakthrough that would be made, progressive supplement and improvement could be accomplished through the mechanism of review and adjustment under the Convention framework. This path represents a combination of bottom-up and top-down. The ultimate way out of international climate negotiation lies in win-win cooperation. Profound reasons for China to participate proactively and practically in international climate negotiation,based on its actual conditions, are the internal wants and needs of its scientific and sustainable development, as well as the undertaking of international responsibilities as a responsible, large, developing country.

Carbon Budget Proposal:An Institutional Framework for an Equitable and Sustainable World Climate Regime

Consensus on reducing greenhouse gas emissions has been reached at the technical and political level.However,as the issue involves economic costs and the right to develop,the international institutional framework for addressing greenhouse gas emissions has consistently failed to balance the demands of impartiality and sustainability.However,a sustainable carbon budget proposal is undoubtedly achievable if the global carbon budget (the total amount of carbon permitted by climate security) is made an absolute constraint.If a preliminary distribution was made among the world's population on a per capita basis,the total limited global carbon budget could not only meet basic needs but also ensure the proposal's equitable.Taking into account historical emission levels and future needs,we should carry out carbon budget transfer payments and devise a corresponding funding mechanism to ensure efficient allocation under the proposal.Unlike the phase-by-phase progress and provisional goals of the Kyoto Protocol,the carbon budget proposal outlined above is a comprehensive and holistic package.Due to the politicization of the climate change issue,however,many technical issues can only be worked out through international political and diplomatic negotiations.

《海牙规则》之回顾与启示

《海牙规则》是船货双方利益妥协的产物,以统一提单若干法律规则为宗旨,具有调整内容的限定性、法律规范的强制性和规则内容的明确性之特点,其实施至少在20世纪60年代基本实现了海上货物运输法律国际化,且对当前这一领域的国际化仍然发挥着基础性作用。《汉堡规则》和《鹿特丹规则》采用的承运人责任规则超出海上贸易实际需求,以及在上述特点方面存在不足,是其未能发挥实现海上货物运输法律国际化作用的主要原因。在正确认识海上货物运输条约与国内法的关系、立法的共性和差异基础上,中国在对参加《鹿特丹规则》持谨慎态度的同时,应当在《海商法》修改时积极借鉴或吸收该规则中合理和成熟的内容,优化《海商法》第四章采用的“混合制度”。

地位满意度与印度的国际机制合作行为

近年来,印度愈发注重通过参与国际机制合作来提升本国的国际地位,并在不同的国际机制中展现出差异性的合作行为。既有研究缺乏对印度在不同机制中合作行为的比较,因此本文结合角色理论,在分析框架中引入“地位”这一变量来阐释印度的国际机制合作行为。“地位满意度”是指一国在国际机制中的实际地位与预期地位的比较和匹配,不同的“地位满意度”将引发不同的国家角色建构,并最终导致特定的国家行为。案例分析表明,作为新兴崛起国的印度具有追求国际地位的强烈动机,其在联合国安全理事会、南亚国家区域合作联盟以及“印太经济框架”中分别建构了“变革者”“控制者”以及“有限合作者”的角色,并展现了相应的合作行为。研究表明,虽然印度对于参与国际机制合作乃至多边主义的态度日趋积极,但鉴于其一贯的自利做法,恐难以在国际机制合作中真正践行多边主义原则。

China, the G20 and the International Investment Regime

China has become a major home country for outward foreign direct investment （OFDI） flows. As a result, the country is increasingly concerned with protecting its OFDI and facilitating the operations of its firms investing abroad and creating a strong universal international investment law and policy regime. This article briefly reviews the emergence of China as an outward investor. It continues with an analysis of some policy issues related to the rise of FDIfrom emerging markets. A brief discussion of issues central to the future of the international investment law and policy regime follows, before focusing on several outcomes that could be pursued under China＇s G20 leadership： non- binding shared principles that could outline the architecture of a universal framework on international investment; an international support program for sustainable investment facilitation; and the creation of an additional intergovernmental platform that would allow for a continued systematic intergovernmental process to discuss the range of issues related to the governance of international investment, preferably paralleled by an informal, inclusive and result-oriented consensus-building process that takes place outside intergovernmental settings.

Carbon budget proposal： a framework for an equitable and sustainable international climate regime

A worldwide consensus on reducing greenhouse gas emissions has been reached at the technical and political level. However, as the issue involves economic costs and developmental interests, the international institutional framework for addressing global greenhouse gas emissions has consistently failed to balance the demands of equity and sustainability. But the sustainability of carbon budget proposal is undoubtedly achievable if the total global carbon budget （the total amount of carbon permitted by climate security） is made an absolute constraint. If an initial allocation is made among all members of the global village on a per capita basis, a limited total budget could not only meet basic needs but also ensure equity. Taking into account historical emission levels and future needs, we should implement carbon budget transfer payments and devise a corresponding financial mechanism to ensure efficient allocation. Unlike the phase-by-phase progress and provisional goals of the Kyoto Protocol, the carbon budget proposal presented here is a comprehensive and holistic package. Due to the politicization of the climate change question, however, many technical issues can only be worked out through international political and diplomatic negotiations.

汇率制度变迁如何影响企业出口贸易?

基于对称开放两国模型的一般均衡分析框架,采用中国贸易企业的微观数据,研究中国与贸易伙伴国双边事实汇率制度安排影响企业出口贸易的微观机制。研究表明:一方面,固定汇率制度通过降低风险提升了所有企业出口,即存在正向规模效应;另一方面,固定汇率制度阻碍了生产要素从低效率企业流向高效率企业,不利于高效率企业出口,即存在负向结构效应。一旦企业生产效率超过一定阈值,负向结构效应会超过正向规模效应,浮动汇率反而更有益于国际贸易增长。因此,从国际贸易平稳发展角度看,相对于汇率制度改革,企业生产率水平提升才是更根本的因素。

教育类国际非政府组织的组织结构与运行机制考察——基于五个教育类国际非政府组织的调研

基于5个教育类国际非政府组织的考察发现,教育类国际非政府组织的决策机构主要有全体大会、理事会或执行委员会、工作委员会或特别工作组三个层级。其中,全体大会通常为最高决策机构;议事规则为达到所规定的最低参会人数,投票表决,通常以简单多数为标准;执行委员会和秘书处是执行决策机构。制度互动和体制互动是教育类国际非政府组织运行及开展基本活动的范式。其中制度互动包括组织结构互动、政治性互动和功能性互动。体制互动包括制定各类教育标准,开展教育水平认证;畅通学术交流渠道和学术激励机制,构建学术共同体;强化学术对话,拓展学术共同体意识。因此,中国要发起或主导教育类国际非政府组织的路径是:推动中国教育话语的国际传播,深度参与或主导教育标准制定,鼓励高校成为发展教育类国际非政府组织的主力军,借力“一带一路”倡议实施推动开展教育类国际非政府组织的共建实践。

Experimental and numerical investigation on the gas leakage regime for ventilated tail cavity of an underwater vehicle

The objective of this paper is mainly to investigate the ventilated tail cavity flow of an underwater vehicle with focus on the gas leakage regime by experimental and numerical methods.A high-speed camera and pressure measurement system are used to record the cavity flow patterns and pressure behavior,respectively.The numerical simulation is carried out with volume of fluid(VOF)model and Filter-based turbulence model(FBM).Good agreement can be obtained between the experimental and numerical results.There are three gas leakage types in the evolution of the intact tail cavity,i.e.,twin-vortex tube entrainment(TVTE),toroidal vortex shedding(TVS)and hybrid twin-vortex tube entrainment and toroidal vortex shedding(TVTE-TVS).With the increase of Fr,the unsteady behavior of the cavity with different gas leakage types becomes more apparent.The internal flow characteristics revealed three distinct regions including the ventilation influence region,the reverse flow region and the high shear flow region and have an important effect on the transition of gas leakage regime.

默许程度与生存空间:缅甸军人政权的国际合法性分析

2021年缅甸军人重新接管国家政权后,面临着与以往军人接权不同的国际合法性困境,但这些困境仍是有限的、非致命的。国际合法性并非简单的承认或不承认,而经常体现为介于两者之间的模糊地带,即因外部默许程度的变化而产生差异的国际生存空间。联合国、东盟、域内外大国等国际行为体,基于对缅甸身份、利益、规范和权力认知的差异,给予缅甸军人政权不同程度的默许,使其能够大致维系最低的国际合法性。军人政权要走出国际合法性困境,需尽可能地调和各利益相关方的矛盾,兑现选举承诺,完成政治转型,中短期内势必经历阵痛。基于不同默许程度的衡量,系统梳理不同国际行为体的对缅政策,甄别不同指标的国际合法性,可为判断2021年军人接权后的未来走势提供参考。

“负责任外空行为”议程与太空安全机制新动向

近年来,太空安全环境发生急剧变化,各国太空军事化步伐加速,商业航天崛起,太空拥挤加剧,太空军民融合加深。在此背景下,英国于2020年发起一项名为“负责任外空行为”的太空军控新议程。该议程推出后,美国积极参与并试图将之导向一项自愿承诺禁止地基动能反卫星试验的国际协议,这意味着其太空军控立场的重大转向。美国意图借“负责任外空行为”议程干扰对手发展不对称反卫星手段、强化太空同盟、划定太空威慑“红线”、策应太空环境议题。“负责任外空行为”已成为太空安全机制领域最有影响力的议程,不仅因为其引发了大国间政治矛盾,还因其体现了太空安全机制的发展动向。在新的太空安全环境下,太空军事安全和民事安全的国际机制正交叉融合发展,各机制的议程模式将更加开放、参与者更加多样、控制行为的路径更加主流。

国际秩序失衡的内在逻辑与中国的应对之策

国际秩序失衡是当今世界的主要特征,特别是在俄乌冲突爆发后愈发明显。与此同时,新兴大国威胁论甚嚣尘上,并逐渐成为西方国家自由国际秩序排他性政策合法性的来源。然而,行为体的权力偏好变迁与秩序内主导性制度衰败是导致国际秩序失衡的深层原因。在多边主义政治秩序僵化与民主国家间自由国际秩序加速衰败的背景下,西方国家不仅疲于应对内部治理危机,还希冀通过政策调整获得结构性权力的相对优势以保持竞争领先。囿于霸权国预防性政策要求其他大国“选边站”,新兴大国无法通过现有多边主义秩序推进全球化、全球治理与规范塑造。对此,以中国为代表的新兴大国首先应通过可塑性较强的双边制度管控分歧,实现与霸权国的良性竞争,其次通过现有或重建多边主义制度保持与其他大国的议题联系,解决全球治理难题,谋求规范化共识的塑造。

规制的形成、演进动力与有效性——奥兰·扬国际规制理论述评

在国际规制形成的问题上,奥兰·扬打破了传统现实主义与功利主义的两分法,将国际规制视为制度谈判的产物。奥兰·扬通过对国际规制的演进动力分析,实现了国际规制研究从静态分析到动态观察的转变。另外,他对国际规制有效性的研究也进一步拓展了国际规制理论研究的议程。在复合性思维影响下,奥兰·扬强调国际规制理论与实践的相互作用,倡导并创设了一套跨越范式、理论与方法的规制复合体,以此来有效应对当今全球治理面临的挑战。在国际规制理论发展与创新层面,奥兰·扬一直处于领先地位,其贡献不仅仅局限于学术界,也在北极治理与环境治理的实践中发挥了重要作用。

《联合国海洋法公约》序言中“一般国际法”的界定与适用

《联合国海洋法公约》序言将其未予规定的事项诉诸一般国际法规则和原则。一般国际法在《联合国海洋法公约》通过以来未得到充分重视,各国也较少直接将其作为海洋确权的法律依据,导致中国以此构建海洋权利主张存在难度。对一般国际法的界定可将国际法委员会报告作为重要参考,将其归纳为包含习惯国际法、一般法律原则、国际与国内法普遍适用的规则,以及法律效力位阶更高的强行法,在国际条约、法院规约、司法实践及海洋领域广泛运用。一般国际法实质有效且有法律约束力,对于规则与权利的确认具有重要的价值。中国可运用一般国际法构建海洋权利主张,从诚实信用、有约必守、禁止反言等一般法律原则角度构建南海历史性权利,以正在形成中的习惯国际法为大陆国家远洋群岛制度提供法律依据,满足国家海洋维权的现实需求,促进《联合国海洋法公约》适用与海洋法新发展。

国际机制视角下的全球海洋治理效能提升

推进全球海洋治理变革是时代发展的重要课题,既有研究主要从主体、理念、规范的视角去探讨如何提升治理效能。国际机制理论为全球海洋治理效能提升提供了新的研究视角。行为体利益和体系动力是影响国际机制生成的自变量。当下的全球海洋治理机制取得了一定进展,但也存在海洋治理机制对治理主体的规范力不足、治理机制难以应对治理客体的困境。未来,为提升全球海洋治理机制效能,应当聚合机制主体的共同利益、增强机制发展的体系动力。

1972年跨国石油公司与欧佩克围绕石油参股问题的博弈

为了维护产油国的石油权益,欧佩克于20世纪70年代初掀起收回石油资源主权的高潮。1972年1月21日到10月5日,欧佩克与跨国石油公司进行石油参股谈判,双方代表签署了《纽约协议》。这一协议是双方妥协的产物。欧佩克把最初参股比例从20%提高到25%,石油公司获得了比欧佩克最初方案更多的补偿。该协议使欧佩克国家逐渐获得对其石油资源的主权,导致跨国石油公司控制产油国石油的国际石油机制进一步瓦解。在谈判过程中,跨国石油公司对欧佩克的态度,从拒绝欧佩克的参股要求转变为基本上接受欧佩克的要求。其动因包括:维护跨国石油公司的经济利益,欧佩克的壮大和斗争,中东地区局势的演进,世界石油生产中心向中东转移。

国际视野下的中国资历框架研究

终身教育体系建设的本质是制度创新,核心任务是建立一套鼓励终身学习、支持终身学习的制度,其中资历框架是最基础的制度,只有以资历框架为基础,其他制度才能逐步建立起来。我国目前尚未建立系统完整的国家层面的资历框架,虽对资历框架建设作了政策准备,但颁布的政策主要提出继续教育的学分累积与转换制度的重要性,并未明确资历框架的核心制度、运作机制、管理模式、实施主体等;国内关于资历框架的研究主要是国外经验介绍以及对资历框架中关键制度"学分银行"的探索,而对资历架构整体的认识及其对终身学习体系建设的重要意义还有待进一步深化;我国的资历框架相关实践已经积累了大量的宝贵经验,但实践探索的范围还非常有限,尚未形成完善的学习成果认证机制和组织机构,无法从根本上构建完整的"学分转换体系"。从国际经验看,建立资历框架也是破解当前我国终身教育的制度瓶颈,切实推进我国终身教育实践的关键。资历框架的建立应列为重点工程尽快开展,立法和质量保证是资历框架顺利实施的法律保障和质量保障。

基坑支护结构内力及变形动态分析

本文提出了一种基坑支护结构内力及变形动态分析的弹性地基梁有限元计算方法，并结合一个工程实例，分析了基坑开挖过程支护结构体系内力及变形的变化过程， 计算表明， 该方法与传统方法相比， 更符合工程实际。