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。     

Visible light photocatalytic bismuth oxide coatings are effective at suppressing aquatic cyanobacteria and degrading free-floating genomic DNA

Access to safe drinking water free from microbial pollution is an issue of global concern. The use of photocatalytic thin films in water treatment has focused on titanium dioxide, which requires UV-activation, proving a potential barrier to upscaling and implementation in the real world. Visible-light-activated photocatalytic thin films, such as bismuth oxide, have recently been shown to have antimicrobial properties. However, more understanding of the photocatalytic effect on the microbial population in water is required. Glass beads coated with bismuth oxide were incubated with either Microcystis aeruginosa, Anabaena sp. or free-floating genomic DNA. The presence of bismuth oxide-coated glass beads was able to rapidly stop a population of cyanobacteria from increasing. The coated beads were also able to degrade genomic DNA. Leachate from the beads showed no increase in toxicity against human liver cells. This data demonstrates the efficacy of bismuth oxide-coated glass beads for controlling potentially dangerous cyanobacterial populations, whilst potentially reducing the amount of free-floating genomic DNA (an essential issue in the face of antimicrobial resistance) – all of which should be essential considerations in emerging water treatment technologies.     

Reflections on network governance in Africa's forestry sector

International forestry governance is an integral part of the global policy debates on how to prevent deforestation, illicit extraction, and unsustainable timber practices. Africa is an important producer of timber, yet the region is beset by a lack of capacity and other governance challenges in the management of its forestry sector. We employ a network governance analysis to examine the extent to which the evolution and operation of the Forest Stewardship Council (FSC) and la Commission des Forêts d'Afrique Centrale (COMIFAC) have addressed governance challenges. We assess the strengths and weaknesses of these two leading examples of international forestry governance by introducing recent evidence and insights from Africa. We conclude with a policy‐relevant discussion of how the FSC and COMIFAC might enhance authority, legitimacy, and effectiveness and improve forestry governance in Africa and other parts of the world.     

Multi-factors influencing the spatial distribution of polycyclic aromatic hydrocarbons in soils surrounding drinking water protection zone

We selected the Guanting Reservoir in Beijing, China as a case where an industrial area locates on the upwind corner to study the influence of human activities and natural processes on the distribution of polycyclic aromatic hydrocarbons (PAHs) in soils. Soil PAH concentrations in the study area follow a log-normal probability distribution function, suggesting that distribution of PAH in soils was affected by human activities. Distribution of PAHs in soils was significantly affected by the point source that high PAH concentrations were observed in near industrial area with an obvious declining trend from the northwest to the southeast which was the prevailing wind direction in this area. Away from the influence of point source, distribution of PAHs in soils was found to significantly correlate with total organic carbon content, while the influences of agricultural land uses and type of soil texture on the total soil PAHs contents and ring compositions were quite limited. The results can provide some evidences and data on the pollutant accumulation in drink water protection area influenced by natural processes and human activities.     

A new fossil thryonomyid from the Late Miocene of the United Arab Emirates and the origin of African cane rats

Cane rats (Thryonomyidae) are represented today by two species inhabiting sub-Saharan Africa. Their fossil record is predominately African, but includes several Miocene species from Arabia and continental Asia that represent dispersal events from Africa. For example, Paraulacodus indicus, known from the Miocene of Pakistan, is closely related to living Thryonomys. Here we describe a new thryonomyid, Protohummus dango, gen. et sp. nov., from the late Miocene Baynunah Formation of the United Arab Emirates. The new thryonomyid is less derived than “Thryonomys” asakomae from the latest Miocene of Ethiopia and clarifies the origin of crown Thryonomys and the evolutionary transition from Paraulacodus. A phylogenetic analysis shows Protohummus dango to be morphologically intermediate between Paraulacodus spp. and extinct and living Thryonomys spp. The morphological grade and phylogenetic position of Protohummus dango further supports previous biochronological estimates of the age of the Baynunah Formation (ca. 6–8 Ma).     

Integrating Environmental and Socio-Economic Indicators of a Linked Catchment–Coastal System Using Variable Environmental Intensity

Can we develop land use policy that balances the conflicting views of stakeholders in a catchment while moving toward long term sustainability? Adaptive management provides a strategy for this whereby measures of catchment performance are compared against performance goals in order to progressively improve policy. However, the feedback loop of adaptive management is often slow and irreversible impacts may result before policy has been adapted. In contrast, integrated modelling of future land use policy provides rapid feedback and potentially improves the chance of avoiding unwanted collapse events. Replacing measures of catchment performance with modelled catchment performance has usually required the dynamic linking of many models, both biophysical and socio-economic—and this requires much effort in software development. As an alternative, we propose the use of variable environmental intensity (defined as the ratio of environmental impact over economic output) in a loose coupling of models to provide a sufficient level of integration while avoiding significant effort required for software development. This model construct was applied to the Motueka Catchment of New Zealand where several biophysical (riverine water quantity, sediment, E. coli faecal bacteria, trout numbers, nitrogen transport, marine productivity) models, a socio-economic (gross output, gross margin, job numbers) model, and an agent-based model were linked. An extreme set of land use scenarios (historic, present, and intensive) were applied to this modelling framework. Results suggest that the catchment is presently in a near optimal land use configuration that is unlikely to benefit from further intensification. This would quickly put stress on water quantity (at low flow) and water quality (E. coli). To date, this model evaluation is based on a theoretical test that explores the logical implications of intensification at an unlikely extreme in order to assess the implications of likely growth trajectories from present use. While this has largely been a desktop exercise, it would also be possible to use this framework to model and explore the biophysical and economic impacts of individual or collective catchment visions. We are currently investigating the use of the model in this type of application.     

A free-enzyme catalyst for the bioremediation of environmental atrazine contamination

Herbicide contamination from agriculture is a major issue worldwide, and has been identified as a threat to freshwater and marine environments in the Great Barrier Reef World Heritage Area in Australia. The triazine herbicides are of particular concern because of potential adverse effects, both on photosynthetic organisms and upon vertebrate development. To date a number of bioremediation strategies have been proposed for triazine herbicides, but are unlikely to be implemented due to their reliance upon the release of genetically modified organisms. We propose an alternative strategy using a free-enzyme bioremediant, which is unconstrained by the issues surrounding the use of live organisms. Here we report an initial field trial with an enzyme-based product, demonstrating that the technology is technically capable of remediating water bodies contaminated with the most common triazine herbicide, atrazine.     

Assessment of Integrated Pedestrian Protection Systems with Autonomous Emergency Braking (AEB) and Passive Safety Components

Objective: Autonomous emergency braking (AEB) systems fitted to cars for pedestrians have been predicted to offer substantial benefit. On this basis, consumer rating programs—for example, the European New Car Assessment Programme (Euro NCAP)—are developing rating schemes to encourage fitment of these systems. One of the questions that needs to be answered to do this fully is how the assessment of the speed reduction offered by the AEB is integrated with the current assessment of the passive safety for mitigation of pedestrian injury. Ideally, this should be done on a benefit-related basis.

The objective of this research was to develop a benefit-based methodology for assessment of integrated pedestrian protection systems with AEB and passive safety components. The method should include weighting procedures to ensure that it represents injury patterns from accident data and replicates an independently estimated benefit of AEB.

Methods: A methodology has been developed to calculate the expected societal cost of pedestrian injuries, assuming that all pedestrians in the target population (i.e., pedestrians impacted by the front of a passenger car) are impacted by the car being assessed, taking into account the impact speed reduction offered by the car's AEB (if fitted) and the passive safety protection offered by the car's frontal structure. For rating purposes, the cost for the assessed car is normalized by comparing it to the cost calculated for a reference car.

The speed reductions measured in AEB tests are used to determine the speed at which each pedestrian in the target population will be impacted. Injury probabilities for each impact are then calculated using the results from Euro NCAP pedestrian impactor tests and injury risk curves. These injury probabilities are converted into cost using “harm”-type costs for the body regions tested. These costs are weighted and summed. Weighting factors were determined using accident data from Germany and Great Britain and an independently estimated AEB benefit. German and Great Britain versions of the methodology are available. The methodology was used to assess cars with good, average, and poor Euro NCAP pedestrian ratings, in combination with a current AEB system. The fitment of a hypothetical A-pillar airbag was also investigated.

Results: It was found that the decrease in casualty injury cost achieved by fitting an AEB system was approximately equivalent to that achieved by increasing the passive safety rating from poor to average. Because the assessment was influenced strongly by the level of head protection offered in the scuttle and windscreen area, a hypothetical A-pillar airbag showed high potential to reduce overall casualty cost.

Conclusions: A benefit-based methodology for assessment of integrated pedestrian protection systems with AEB has been developed and tested. It uses input from AEB tests and Euro NCAP passive safety tests to give an integrated assessment of the system performance, which includes consideration of effects such as the change in head impact location caused by the impact speed reduction given by the AEB.