An iterative method for simultaneously computing the synthesis of light and heavy elements

We propose an iterative algorithm for computing the synthesis of heavy elements through the rapid capture of neutrons (r-process) and, at sufficiently high temperatures, protons by simultaneously using two distinct computer codes. One of the codes describes the kinetics of nuclear reactions between light and intermediate chemical elements, which are the source of free neutrons and protons used by the second code to synthesize heavy elements from seed nuclides (isotopes near the iron peak of the cosmic abundance curve). The two codes interact through the neutron and proton reaction channels. We demonstrate the efficiency of our method with an example of the nucleosynthesis in a supernova’s helium shell triggered by the evaporation of neutrons and protons from α particles exposed to the neutrino flux from a collapsing stellar core. In this case, three or four iterations are enough to obtain an almost exact self-consistent solution.     

玄武岩纤维堵漏体系在高海拔非开挖钻进中的应用研究

高海拔地区实施非开挖水平定向钻进时,裂隙发育地层的泥浆漏失不仅会影响泥浆的有效循环,还会形成大量的岩屑床,导致钻具过度磨损、摩阻异常增大、有效孔径减小等问题。针对西藏某地钻遇花岗岩裂隙,采用近景摄影测量技术对其进行量化表征,得到该区裂隙地层的缝宽<4 mm;提出采用玄武岩纤维作为裂隙封堵主剂,并建立随钻玄武岩纤维堵漏配方体系,实验结果表明：采用3、6和9 mm多级组合的玄武岩纤维堵漏效果最好,3 mm纤维复合惰性材料形成骨架结构,6和9 mm纤维可发挥一定强度的“加筋”作用。现场随钻实验结果表明：采用玄武岩纤维堵漏后,泥浆中固相含量下降幅度减少了13.14%,有效保障了长距离裂隙山体的有效、绿色、安全钻进。     

地表水渗漏对娘子关岩溶泉泉水水质的影响

娘子关泉水作为阳泉市主要的供水水源,受特定地质结构与人为污染等因素的影响,水质呈现逐年恶化的趋势,部分组分含量目前已处于超标或临界超标状态。在分析泉域岩溶水系统地质结构基础上,通过泉域内各主要河流渗漏量实测与水化学测定,采用物理混合方法评价河流渗漏途径对娘子关泉水水质的污染影响程度。     

新疆坡北矿区ZK2-6孔钻探施工技术

新疆坡北矿区ZK2-6孔施工中遇到多层蚀变带,最长连续强蚀变带达30 m,在以往施工过程中,因卤水配制的泥浆性能难以保证,不利于孔壁的稳定,导致在钻进过程中,孔壁剥落超径、断钻杆事故频发。钻杆断开后,由于孔壁坍塌,找不到事故头,从而导致钻孔报废。针对蚀变、破碎地层钻进易发生的孔壁坍塌、超径、掉块及卤水泥浆性能难以保证等问题,开展相关研究,提出相应的技术措施,圆满完成了坡北工区ZK2-6孔的钻探施工。     

凝胶堵漏技术在阳山矿区漏失地层中的应用

甘肃省文县阳山矿区地质构造复杂,地层破碎蚀变强烈,多层位漏失,钻探施工漏失现象普遍。在研究地层漏失机理的基础上试验应用了聚合物凝胶堵漏技术。ZK2232孔的现场应用表明,聚合物凝胶堵漏剂与其他惰性桥堵剂配合使用,能很好地解决钻进过程中的恶性漏失问题,堵漏效果较好。在堵漏施工中,聚合物凝胶堵漏不受漏失通道的限制,能够通过挤压变形进入裂缝和孔洞空间,最终达到封堵漏层的目的。     

赤泥库大坝渗漏分析及灌浆处理技术

由于施工质量问题,洛阳一个赤泥库大坝在试运行中发生大面积渗漏及管涌。在对渗漏原因进行分析的基础上实施的在坝内坡增设土工膜、坝轴线上游增设帷幕灌浆防渗墙、坝体下游坡面增设排渗沟和排水棱体等抢险加固措施,有效地解决了坝体渗漏问题。在灌浆处理过程中,针对筑坝材料的复杂性和不均匀性,通过施工前的灌浆试验,取得了适合本场地条件的钻孔施工工艺参数及灌浆方式、灌浆压力、灌浆段确定、水灰比比级等施工技术参数,确保了灌浆处理的效果。     

Biomass strategies for climate policies?

Abstract

This paper discusses the results of the BEAP linear programming model that has been developed to study the optimal use of biomass and land for greenhouse gas emission reduction, notably the competition between food production, biomass production for energy and materials and afforestation. The model results suggest up to 100 EJ biomass use in case of global policies (about 20% of global primary energy use). The biomass is used for industrial and residential heating, transportation fuels and as a feedstock for plastics. In the electricity markets competing emission reduction options are more cost-effective than biomass. In case the Kyoto protocol is continued beyond 2010 the developed countries can rely in 2020–2030 on afforestation and land use change credits from developing countries, without any major use of other emission reduction strategies. However, in case of a planning perspective of more than half a century bioenergy is preferred instead of afforestation. The results indicate a limited impact on global agricultural trade, but food demand may be affected by CO₂ policies.     

The design of California's cap-and-trade and its impact on electricity markets

California is considering the adoption of a cap-and-trade regulatory mechanism for regulating the greenhouse gas emissions from electricity and perhaps other industries. Two options have been widely discussed for implementing cap-and-trade in the electricity industry. The first is to regulate the emissions from electricity at the load-serving entity (LSE) level. The second option for implementation of cap-and-trade has been called the ‘first-seller’ approach. Conceptually, under first-seller, individual sources (i.e. power plants) within California would be responsible for their emissions, as with traditional cap-and-trade systems. Emissions from imports would be assigned to the ‘importing firm’. An option that has not been as widely discussed is to implement a pure source-based system within California, effectively excluding imports from the cap-and-trade system altogether. This article examines these three approaches to implementing cap-and-trade for California's electricity sector. The article discusses many of the issues relating to measurement and the impacts on bidding and scheduling incentives that are created by the various regulatory regimes.     

Historic versus output-based allocation of GHG tradable allowances: a comparison

Two ways of allocating greenhouse gas (GHG) allowances are compared: historic allocation (HA) based solely on past information, and output-based allocation (OBA) based on an allocation proportional to the current output level. The advantages and problems of each allocation method are considered and compared. It is essential to distinguish the sectors sheltered from international competition (e.g. power generation) from the exposed sectors. In the sheltered sectors, OBA entails a much higher overall cost because it provides too little incentive to reduce the production of the polluting goods. HA does not suffer from this drawback but its distributional impact is highly unfair. Hence in these sectors neither of these two ways of freely allocating allowances can be supported, and auctioning should be favoured. However, in the exposed sectors, OBA is an option worth considering because it reduces carbon leakage, although it also suffers from some drawbacks compared with auctioning.