Environmental management of the Colorado River within the Grand Canyon

Irreversible environmental changes are occurring along the Colorado River in the Grand Canyon as a result of regulation of the river flow by the Glen Canyon Dam. The questions of primary importance in managing this great natural resource are 1) in what manner and how rapidly are the physical and ecological adjustments taking place, and 2) is the increased use of the river for recreational boating contributing to the degradation? Human use along the Colorado River is limited, for the most part, to the relic, pre-dam fluvial deposits colloquially called “beaches.” With the new river regime these deposits are positioned well above the present high-water stage, 27,000 cubic feet/second (cfs), or 765 cubic meters/second (cms), so they are not replenished periodically as they were prior to construction of the dam in 1963. The dominant natural processes now are aeolian sand transport and mass wasting. The float-trip passengers use the river beaches for hiking, camping, and. lunch stops. At the most desirable sites thirty to forty people camp on the beaches each night over a four to five month season. Human impact includes incorporation of campsite litter, burial of chemically treated waste, and the direct stress associated with people walking on the vegetation and unstable sedimentary deposits. Results of our investigations indicate that the rate of degradation at the most heavily used sites exceeds the capacity of aeolian processes to reestablish natural landscapes. Therefore, careful management of float trjps is needed if these environments are to be maintained in a natural state rather than a “sand-box” state.     

The challenge of integrating non-continuous processes – milk powder plant case study

The integration of non-continuous processes such as a milk powder plant presents a challenge for existing process integration techniques. Current techniques are generally based on steady and continuous operation which for some industries is not the case. Milk production varies considerably during the year as dairy cows in New Zealand are grazed on pasture. In this paper the potential for indirect heat transfer between the several plants using a heat recovery loop and stratified tank at a typical New Zealand dairy factory is investigated. The maximum amount of heat recovery is calculated for a range of recirculation loop temperatures. The maximum amount of heat recovery can be increased considerably if the temperature of the hot fluid in the recirculation loop is varied depending on which condition the site is operating under.     

一种改进的多学习教与学优化算法

针对传统教与学算法在解决复杂多峰函数优化问题时,具有局部最优且搜索开发能力较差的缺点,提出了一种改进的多学习教与学优化算法,新算法为学员的每一维加入不同的教学因子,设计了基于学员均值比较的教师选择策略和向教师及学员学习的多学习策略。基于多个单峰和多峰函数的仿真结果表明,新算法跟传统的、改进的教与学算法相比,在稳定性、寻优精度和收敛速度方面更具优势。     

Sampling and Mapping a Soil Erosion Cover Factor by Integrating Stratification,Model Updating and Cokriging with Images

Cost-efficient sample designs for collection of ground data and accurate mapping of variables are required to monitor natural resources and environmental and ecological systems. In this study, a sample design and mapping method was developed by integrating stratification, model updating, and cokriging with Landsat Thematic Mapper (TM) imagery. This method is based on the spatial autocorrelation of variables and the spatial cross-correlation among them. It can lead to sample designs with variable grid spacing, where sampling distances between plots vary depending on spatial variability of the variables from location to location. This has potential cost-efficiencies in terms of sample design and mapping. This method is also applicable for mapping in the case in which no ground data can be collected in some parts of a study area because of the high cost. The method was validated in a case study in which a ground and vegetation cover factor was sampled and mapped for monitoring soil erosion. The results showed that when the sample obtained with three strata using the developed method was used for sampling and mapping the cover factor, the sampling cost was greatly decreased, although the error of the map was slightly increased compared to that without stratification; that is, the sample cost-efficiency quantified by the product of cost and error was greatly increased. The increase of cost-efficiency was more obvious when the cover factor values of the plots within the no-significant-change stratum were updated by a model developed using the previous observations instead of remeasuring them in the field.