项目投资决策实物期权方法

假设投资企业具有指数效用函数,项目投资收益服从具有上反射壁的几何布朗运动,项目投资收益不可复制,研究项目投资择时与定价问题,运用随机控制理论和新的证明方法,得到了项目投资择时与定价问题的解析解.     

我国减灾投入与灾害损失关系研究

在获取国家民政局、林业局、统计局、环境保护总局相关数据的基础上,利用SPSS统计软件,对国际减灾十年活动期间与1991-2005年的减灾投入与灾害损失进行了相关与回归分析,认为我国灾害管理体制正在完善,但仍存在很多问题,并提出了相关对策。     

Determination of optimal rotation period under stochastic wood and carbon prices

The valuation of forest stands is traditionally based on a profit calculus involving revenue from wood sales and associated costs. Currently, the role of carbon management in forests is actively discussed. In a stochastic setting we extend the analysis of the optimal rotation period by considering uncertain revenue streams from carbon trading. We develop a real options model given uncertainties in future wood and CO₂ price behaviour. A detailed sensitivity analysis of the numerical results for both cases – with and without carbon sequestration – is provided. We find that optimal rotation periods vary considerably with (i) the type of price process, (ii) the way how carbon income is defined, and (iii) the selection of discount rates.     

Economic incentives for abandoning or expanding gum arabic production in Sudan

In this paper we use a real options approach to analyze farmers' economic incentives to abandon gum production or expand by creating new plantations. Our results indicate that agricultural crops currently provide higher economic benefits as compared to gum agroforestry. However, we show that the incentives for gum producers to abandon gum production is low, because (i) land is abundant, (ii) gum arabic is produced during the dry season and agricultural crops mainly during the wet season, and (iii) the dry season opportunity cost of labor is low. Hence, an increase in deforestation in the near future is not expected. The analysis further shows that an increase in the prices of gum arabic of about 315% is needed to induce an expansion of gum agroforestry and a shift in land use system from continuous agricultural production to gum agroforestry system. Hence, also an expansion of gum forests and/or agroforests in the near future is not expected. Price policies to improve incentives for expanding gum forests are discussed.     

Potassium application reduces methane emission from a flooded field planted to rice

In a field study, potassium (K) applied as muriate of potash (MOP) significantly reduced methane (CH₄) emission from a flooded alluvial soil planted to rice. Cumulative emission was highest in control plots (125.34 kg CH₄ ha⁻¹), while the lowest emission was recorded in field plots receiving 30 kg K ha⁻¹ (63.81 kg CH₄ ha⁻¹), with a 49% reduction in CH₄ emission. Potassium application prevented a drop in the redox potential and reduced the contents of active reducing substances and Fe²⁺ content in the rhizosphere soil. Potassium amendment also inhibited methanogenic bacteria and stimulated methanotrophic bacterial population. Results suggest that, apart form producing higher plant biomass (both above- and underground) and grain yield, K amendment can effectively reduce CH₄ emission from flooded soil and could be developed into an effective mitigation option, especially in K-deficient soils.     

Modelling the efficacy of proposed mitigation areas for shorebirds: a case study on the Seine estuary, France

A behaviour-based model was used to explore the effect of an extension of the port at Le Havre (Port 2000), and the effect of proposed mitigation measures, on the mortality and body condition of the three main shorebird species that overwinter in the estuary of the river Seine, France. In the model, a 20% reduction in the area of mudflats on the north side of the estuary had little effect on curlew Numenius arquata mortality and body condition but significantly increased mortality and decreased body condition in dunlin Calidris alpina and oystercatchers Haematopus ostralegus. Disturbance of feeding birds both day and night had a significant effect on the mortality and body condition of all three shorebird species, as did disturbance of roosting birds. Disturbance of feeding birds in the daytime only had a significant effect on dunlin mortality and body condition, but not that of curlew and oystercatchers. In the model, the creation of a buffer zone to reduce disturbance of feeding birds restored shorebird mortality and body condition to pre-disturbance levels. A new mudflat area was also effective in mitigating the effect of habitat loss on all three shorebirds and in mitigating the effect of roost disturbance on dunlin and curlew. However, a new mudflat area was not effective in mitigating the effect of roost disturbance on oystercatcher mortality and body condition. The effectiveness of the mitigating mudflat depended as much on its size as its quality. We believe that this is the first time that anyone has been able to forecast the efficacy of proposed mitigation measures.     

数字示波器中波形参数自动测量算法研究

假定标的股票服从分数布朗运动,应用二次近似法和偏微分方程方法求出了美式下降敲出看涨、看跌障碍期权价格近似解以及最佳实施边界. 最后,通过显式差分法比较近似解的准确性,并分析Hurst参数对期权价格和最佳实施边界 S* 的影响.     

Uncertainty and investment in precision agriculture – Is it worth the money?

Irreversibility and uncertainty render the standard capital budgeting techniques such as net present value (NPV) analysis insufficient as a decision criterion. The standard NPV underestimates the value of the investment by not including the value of waiting for new information to reduce the uncertainty of the cashflows generated by the investment. An alternative to NPV analysis is real options. In this study, we apply real options analysis to an investment decision for a grain producer in Western Australia. The investment choice is to either purchase machinery suitable for undertaking controlled traffic precision agriculture or acquire a conventional system and reduce sowing time. The results of the analysis suggest that the required rates of return for the two investment alternatives need to be approximately 96–156% higher than the rates of return used in the standard NPV analysis. These higher rates of return are required to compensate for the uncertainty inherent in the cropping systems of the farm. Also, in most cases, even though the variable costs of operating the precision agriculture system were higher, due to smaller operating widths, the additional returns generated by managing zones individually outweighed these additional costs. Further analysis also shows that the relative size of management zones has a marked effect on the returns generated and that it is possible to increase returns by taking out marginally productive zones.     

Mitigating N2O emissions from cropping systems after conversion from pasture − a modelling approach

Converting pasture to cropping is common in many of the world’s agricultural systems. This conversion results in substantial net mineralisation of soil organic matter that builds up during a phase of pasture. A few studies have shown that this mineralisation leads to increased nitrous oxide (N₂O) emissions compared to long-term pasture or long-term cropping. Understanding of interactions leading to these significant emissions is still scarce but is needed to identify mitigation options for this situation. In this study, the Agricultural Production Systems sIMulator (APSIM) was used to investigate the optimal timing of pasture termination (relative to crop planting) and management of nitrogen (N) in crops after pasture termination to maximise crop yield and limit N₂O emissions. Beforehand, APSIM’s performance in simulating yields and N₂O emissions was tested against data from field experiments conducted in the temperate high-rainfall zone of southern Australia where N₂O emissions were monitored with automatic gas collection chambers during the first year of cropping wheat after terminating long-term pasture on two adjacent sites in two consecutive years. Field experiments and simulation scenarios showed very high N₂O emissions (up to 48 kg N₂O-N ha⁻¹ yr⁻¹) in the first year of wheat after pasture termination, even without N fertiliser application. Measured cumulative N₂O emissions, crop yields and soil mineral N and water content dynamics were simulated well with APSIM. Including a routine into APSIM to account for N₂O transport through the soil profile improved the simulation of daily N₂O emissions considerably, leading to up to 67% of the measured variability in daily N₂O emissions being explained by the model. We predicted that a short fallow between termination of pasture and sowing wheat, instead of a long fallow which is the common practice, reduces N₂O emissions by more than half in the first year of cropping without a noteworthy impact on crop yield. Reducing N fertiliser applications in the first few years after pasture termination by taking available soil mineral N into account, and applying the fertiliser six to twelve weeks after sowing instead of at sowing was predicted to further reduce N₂O emissions. Since the model was calibrated against experimental data during the first year after pasture termination only, experiments determining N₂O emissions in the first two or three years after terminating pasture are needed to confirm our predictions.     

坡耕地土壤水分入渗影响因素分析

介绍了千年生态系统的目的、任务、概念框架、实施过程及服务对象等，并提出了中国应该采取的对策。千年生态系统评估的目的是提高对生态系统的管理水平，为决策者提供信息。其任务是评估生态系统现状、预测生态系统的未来变化、提出对策、在典型地区实施评估计划。