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Daniel Whittaker Andreas Geist Giuseppe Modolo Robin Taylor Mark Sarsfield Andreas Wilden 《溶剂提取与离子交换》2018,36(3):223-256
Over the last decade there has been much interest in the applications of diglycolamide (DGA) ligands for the extraction of the trivalent lanthanide and actinide ions from PUREX high active raffinates or dissolved spent nuclear fuel. Of the DGAs, the N,N,N’,N’-tetraoctyldiglycolamide (TODGA) is the best known and most widely studied. A number of new actinide separation processes have been proposed based on extraction with TODGA. This review covers TODGA-based processes and extraction data, specifically focusing on how phase modifiers have been used to increase metal loading and thus enhance the operating process envelopes. Effects of third phase formation and the organic phase speciation are reviewed in this context. Relevant aspects of the extraction chemistry of important solvents (TODGA-modifier-diluent combinations) are described and their performances demonstrated by a consideration of the published flowsheet tests. It is seen that modifiers are successfully enabling the use of TODGA in actinide separation processes but to date the identification and testing of suitable modifiers has been rather empirical. There is a growing understanding of the fundamental chemistry occurring in the organic phase and how that affects extractant speciation and metal loading capacity but studies are still needed if TODGA-based flowsheets are to become an industrially deployable option for minor actinide (MA) recovery processes. 相似文献
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Risk allocation decisions are of critical importance in project management. The present study proposes an explanation for how risk allocation in a contract motivates a contractor to cooperate with a project owner. Theories of risk allocation and trust were used to motivate the research. Using a survey methodology, we collected data concerning 124 construction projects in China. We found that risk allocation influenced the contractor’s role behavior through the contractor’s feeling of being trusted but not the contractor’s trust in the owner. Feeling of being trusted partially mediated the effect of risk allocation on the contractor’s in-role (i.e., contractual) behavior and fully mediated the effect on extra-role behavior. The study introduces a social and psychological view of the impacts of risk allocation to the project and engineering management literature. We contribute to theory by arguing and demonstrating the mediating effect of trust on the relationship between risk allocation and contractor behavior. From a practical standpoint, we conclude that contractual risk allocation has a significant impact on building a trusting relationship between owners and contractors and that contractors who feel trusted perform both contractually mandated actions and actions external to the contract more diligently, resulting in the likelihood of improved outcomes for both parties. 相似文献
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聚合物驱偏心分质注入技术 总被引:6,自引:0,他引:6
大庆油田主力油层聚驱结束后,聚驱驱替对象已转向渗透率更低、层间差异更大的二、三类油层,分注技术面临着新的矛盾。高渗透率油层需要控制注入量,同时要降低粘损率;低渗透油层要适当降低相对分子质量和粘度,以保证不堵塞油层又有足够的注入速度。为此,研究了聚合物驱偏心分质注入技术,可实现对分层相对分子质量、注入量的双重调节,并在注聚区块开展了现场试验,见到了明显效果。 相似文献
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三峡三期工程主坝大体积混凝土内部温度控制 总被引:2,自引:2,他引:0
三峡右岸三期工程施工中,为了有效控制坝体大体积混凝土内部温升,采取了高温季节使用预冷混凝土浇筑、控制混凝土出机口温度及浇筑温度、对混凝土内部人工通水进行初冷、中冷和后冷等措施。三峡三期工程大坝混凝土内部温度没有出现超标现象,混凝土温控工作取得了良好的效果。 相似文献
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Panagiotis N. Zarros Myung J. Lee Tarek N. Saadawi 《Journal of Network and Systems Management》1994,2(4):361-382
In this paper, an algorithm to determine the set of packets generated continuously and periodically from different participants that are arriving at a node either for mixing at the master of a conference, or for simply playing back at a regular participant of a conference, is proposed. The essence of the algorithm is to estimate the expected packet arrival time (or reference time) for each participant. With the reference time at hand, the maximum jitter and the optimum waiting time for a mixer to wait packets from all participants can be determined. An enhancement to improve synchronization which deals with the estimation of the time offsets between the individual periods of the sources and the period of the receiver is also presented. The error of the proposed algorithm is enumerated by the Chernoff bound and demonstrated by simulation and is shown to be acceptable in practical application. The algorithm can also be employed when traffic sources operate with different periods. 相似文献
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3G系统的安全策略分析 总被引:1,自引:0,他引:1
介绍了当前3G系统面临的各种威胁和针对3G的攻击方法,如对非授权数据的非法获取、对数据完整性的攻击和对业务的非法访问攻击等.分析了3G系统的安全体系结构和安全特性的优缺点. 相似文献
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