Pulsed laser micro polishing: Surface prediction model

The objective of this work is to predict the final roughness of metal surfaces that have undergone pulsed laser micro polishing. The motivation for pulsed laser micro polishing is to reduce the surface roughness of parts whose surface texture can approach the feature size. Being able to predict the magnitude of the polishing and frequency (wavelength) content of the surface will assist in the design of optimal processing parameters with minimal experiments. Laser pulses are used to create shallow melt pools with a controlled size (e.g., depth) and duration in order to allow surface tension forces to “pull down” asperities with small radius of curvature. There is no ablation occurring in the process being modeled. The melt depth and duration are predicted with a transient, two-dimensional axisymmetric heat transfer model with temperature-dependent material properties. The surface of the melt pool is analytically modeled as oscillations of stationary capillary waves with damping resulting from the forces of surface tension and viscosity. Above a critical spatial frequency, f_cr, a significant reduction in the amplitude of the spatial Fourier components is expected. The work described in this paper extends the concept of critical frequency to a physics-based prediction methodology for predicting the spatial frequency content and surface roughness after polishing, given the features of the original surface, the material properties, and laser parameters. The proposed prediction methodology was validated using line polishing data for stainless steel 316L and area polishing results for pure nickel, Ti6Al4V, and Al-6061-T6. The predicted average surface roughnesses were within 12% of the values measured on the polished surfaces.     

Using expert elicitation to define successful adaptation to climate change

This paper develops definitions of adaptation and successful adaptation to climate change, with a view to evaluating adaptations. There is little consensus on the definition of adapting to climate change in existing debates or on the criteria by which adaptation actions can be deemed successful or sustainable. In this paper, a variant of the Delphi technique is used to elicit expert opinion on a definition of successful adaptation to climate change. Through an iterative process, expert respondents coalesced around a definition based on risk and vulnerability and agreed that a transparent and acceptable definition should reflect impacts on sustainability. According to the final definition, agreed by the Delphi panel, successful adaptation is any adjustment that reduces the risks associated with climate change, or vulnerability to climate change impacts, to a predetermined level, without compromising economic, social, and environmental sustainability.     

Ozone in Central England: the impact of 20 years of precursor emission controls in Europe

Episodic peak ozone levels over the 1990–2007 period appear to have declined strongly whilst annual mean daily maximum levels have risen over the same period at monitoring sites within the midlands regions of the UK. Sensitivity studies carried out with a photochemical trajectory model have shown that European policies to control Volatile Organic Compound (VOC) and Nitrogen Oxides (NO_x) emissions are the likely cause of the decline in episodic peak levels. There appeared to have been little influence on the episodic peak from changes in intercontinental trans-Atlantic transport but an overwhelming influence on the annual mean daily maximum levels. Non-linear relationships between VOC and NO_x emission controls and ozone, together with the ambition level set by policy-makers, appear to explain why ozone levels in Central England still do not meet internationally accepted air quality guidelines despite two decades of policy actions within Europe.     

Consistency and comparability of estimation and accounting of removal by sinks in afforestation/reforestation activities

The Kyoto Protocol accounting system and its market mechanisms, Clean Development Mechanism (CDM) and Joint Implementation (JI), are built on the key principle that emission and emission reduction units generated by afforestation/reforestation activities under national systems and projects are fully comparable, no matter their origin. Lack of consistency in the quality of emission and emission reduction units can undermine the environmental integrity of the climate stabilization actions. Therefore, it is the ambition that units generated in the land-use, land-use change and forestry (LULUCF) sector are of similar quality with those from non-LULUCF sectors. In this paper, the authors pose the question of whether there is full estimation and accounting consistency between Annex I Party’s national GHG systems and CDM projects methodologies in the LULUCF sector, in terms accuracy, completeness, levels of uncertainty and permanence risk. We focus on methodological aspects related to the applicability and practicability of using approved afforestation/reforestation CDM methodologies; estimation, reporting and accounting rules; the small pools and sources issue, uncertainty of removal estimate; leakage and handling of non-permanence risk. We conclude that there is significant scope for improving the consistency of greenhouse gas emission accounting from land use activities in the post-2012 climate change agreement, between Annex I domestic and project activities. As well, we conclude that the preparation and implementation of project activities has to be made simpler by a project framework guideline, which is then adapted to any project circumstances.     

Perspectives on area-based conservation and its meaning for future biodiversity policy

During 2021, Parties to the Convention on Biological Diversity (CBD) are expected to meet in Kunming, China, to agree on a new global biodiversity framework aimed at halting and reversing biodiversity loss, encouraging the sustainable use of biodiversity, and ensuring the equitable sharing of its benefits. As the post-2020 global biodiversity framework evolves, parties to the convention are being exposed to a range of perspectives on the conservation and sustainable use of biodiversity, relating to the future framework as a whole or to aspects of it. Area-based conservation measures are one such aspect, and there are diverse perspectives on how new targets might be framed in relation to these measures. These perspectives represent different outlooks on the relationship between human and nonhuman life on Earth. However, in most cases there is a lack of clarity on how they would be implemented in practice, the implications this would have for biodiversity and human well-being, and how they would contribute to achieving the 2050 Vision for Biodiversity of “living in harmony with nature.” We sought to clarify these issues by summarizing some of these perspectives in relation to the future of area-based biodiversity conservation. We identified these perspectives through a review of the literature and expert consultation workshops and compiled them into 4 main groups: Aichi+, ambitious area-based conservation perspectives, new conservation, and whole-earth conservation. We found that although the perspectives Aichi+ and whole earth are in some cases at odds with one another, they also have commonalities, and all perspectives have elements that can contribute to developing and implementing the post-2020 global biodiversity framework and achieving the longer term CBD 2050 Vision.     

An automated system to control and manipulate the flight activity of captive birds

Biologists have long been interested in the behavioural and physiological mechanisms that regulate flight. The manipulation of physical activity of birds under captive conditions, however, faces the experimenter with some technical problems. In this article, we describe a simple automated system that allows control and manipulation of the flight activity of captive birds and use it for the first time to induce blood oxidative stress in male zebra finches (Taeniopygia guttata). Finches subjected to a short-term flight effort regime had an increase of plasma oxidative damage and a decrease of thiol concentration in red blood cells and of body mass, respectively. However, no change in red blood cell glutathione peroxidase was observed. This simple experiment shows that our automated system may be successfully used to induce changes in the physiological state of small birds.     

Oceanic variability and coastal topography shape genetic structure in a long-dispersing sea urchin

Understanding the scale of marine population connectivity is critical for the conservation and sustainable management of marine resources. For many marine species adults are benthic and relatively immobile, so patterns of larval dispersal and recruitment provide the key to understanding marine population connectivity. Contrary to previous expectations, recent studies have often detected unexpectedly low dispersal and fine-scale population structure in the sea, leading to a paradigm shift in how marine systems are viewed. Nonetheless, the link between fine-scale marine population structure and the underlying physical and biological processes has not been made. Here we show that patterns of genetic structure and population connectivity in the broadcast-spawning and long-distance dispersing sea urchin Centrostephanus rodgersii are influenced by physical oceanographic and geographic variables. Despite weak genetic differentiation and no isolation-by-distance over thousands of kilometers among samples from eastern Australia and northern New Zealand, fine-scale genetic structure was associated with sea surface temperature (SST) variability and geography along the southeastern Australian coast. The zone of high SST variability is characterized by periodic shedding of eddies from the East Australian Current, and we suggest that ocean current circulation may, through its influence on larval transport and recruitment, interact with the genetic consequences of large variance in individual reproductive success to generate patterns of fine-scale patchy genetic structure. If proven consistent across species, our findings suggest that the optimal scale for fisheries management and reserve design should vary among localities in relation to regional oceanographic variability and coastal geography.     

A theory of scaling for community-based fisheries management

Community-based approaches to fisheries management has emerged as a mainstream strategy to govern dispersed, diverse and dynamic small scale fisheries. However, amplifying local community led sustainability outcomes remains an enduring challenge. We seek to fill a theoretical gap in the conceptualization of ‘scaling up community-based fisheries management’. We draw on literature of agriculture innovations to provide a framework that takes into account process-driven and structural change occurring across multiple levels of governance, as well as different phases of scaling. We hypothesize that successful scaling requires engagement with all aspects of a governing regime, coalescing a range of actors, and therefore, is an enterprise that is larger than its parts. To demonstrate where the framework offers value, we illustrate the development of community-based fisheries management in Vanuatu according to the framework’s main scaling dimensions.     

Development of a MSW classification system for the evaluation of mechanical properties

To date, sparse information is available on the mechanical properties of municipal solid waste and the results of published work are often hard to compare due to differences in waste composition and therefore properties. To allow comparison, a unified classification system for waste is deemed crucial. Existing classification systems are presented and discussed. For a geotechnical classification, mechanical properties, size, shape and degradability potential of waste components have to be taken into account. A new and improved classification system for waste components is proposed, which complies with the requirements of a geotechnical classification system. It classifies waste components based on: (1) their material engineering properties (e.g., shear, compressive and tensile strength), (2) a size distribution of the components, (3) the component shape (reinforcing, compressible and incompressible), and (4) the degree of degradability. The proposed classification system is applied to data from the literature and methods for presenting classification information are demonstrated. Further work required to develop a full classification system for waste bodies is highlighted.     

采用大气压电喷雾(API-ESI)质谱和液体样品直接大体积进样技术检测饮用和地下水中的苯基脲类和三嗪类除草剂

本文介绍了大体积进样技术分析一组苯基脲类和三嗪类除草剂多残留的简便方法.