Modeling and simulation of arc: Laser and hybrid welding process

Welding is a fabrication process to join two different materials. Among the many welding processes, the arc and laser welding processes are the most widely used. Great effort is required to understand the physical phenomena of arc and laser welding due to the complex behaviors which include liquid phase, solid phase and, gas phase. So it is necessary to conduct numerical simulation to understand the detailed procedures of welding. This paper will present the various numerical simulation methods of the arc welding processes such as arc plasma, gas tungsten arc welding, gas metal arc welding, laser welding, and laser–arc hybrid welding. These simulations are conducted by the finite element method, finite differential method and volume of fluid method to describe and analyze the various welding processes.     

Oxidation of Toluene on γ-Al2O3 Supported Copper–Manganese Catalysts

Abstract Catalytic incineration of toluene over γ-Al2O3-supported copper–manganese oxide catalysts in the temperature range of 433?K–553?K was investigated using a fixed-bed flow reactor. Catalysts were characterized using Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, temperature-programmed reduction, temperature-programmed oxidation, X-ray photoelectron spectroscopy, and X-ray diffraction. Incineration of toluene was achieved at temperatures up to 553?K and it was found that the weight ratio of reactants (Cu:Mn) was optimized to be 15:10. Brunauer-Emmett-Teller surface area results had no correlation with the activity of the catalysts. Results of temperature-programmed reduction/temperature-programmed oxidation and X-ray photoelectron spectroscopy showed that the redox peak of the 15Cu-10Mn catalyst shifted at lower temperatures and the binding energy shifted toward higher oxidation levels. These results show that high binding energy and high redox capacity are the causes of...     

Plenty of water,not enough strategy: How inadequate accessibility,poor governance and a volatile government can tip the balance against ensuring water security: The case of Nepal

Water security is arguably the single most important factor regarding the future sustainability of our planet. Without water we have no life, and with depleting freshwater resources conflict can easily ensue. The intersection between hydrology and politics requires a delicate balancing from decision-makers to ensure policy is well-informed and science is well communicated. In this paper, we discuss water issues currently faced by Nepal, a nation where freshwater resources are abundant yet political pressures are threatening future water security. We argue that despite adequate water supplies a nation may still experience severe water insecurity, particularly if effective governance and equitable access are not prioritised. We explore potential policy options necessary to achieve a holistic framework for water resources management, which we suggest, need to consider water resource reliability, accessibility and governance as fundamental pillars for ensuring water security.     

Unusual prenatal presentation of Beckwith–Wiedemann syndrome

When Beckwith–Wiedemann syndrome (BWS) is detected prenatally, it is usually on the basis of macroglossia, exomphalos or enlarged kidneys. We describe a case that presented as gross hepatomegaly and a suspected enlarged pancreas at 20 weeks' gestation, with none of the usual features. Copyright © 2004 John Wiley & Sons, Ltd.     

Environmental,economic and social costs and benefits of a packaging waste management system: A Portuguese case study

The impact of the management of packaging waste on the environment, economic growth and job creation is analyzed in this paper. This integrated assessment intends to cover a gap in the literature for this type of studies, using the specific case study of the Portuguese packaging waste management system (SIGRE).The net environmental benefits associated with the management of packaging waste, are calculated using the Life Cycle Assessment methodology. The results show that, for the categories studied, the impacts associated to SIGRE's various activities are surpassed by the benefits associated to material and energy recovery, with special focus on recycling. For example, in 2011 SIGRE avoided the emission of 116 kt CO₂ equiv. – the equivalent carbon emission of the electricity consumption of 124.000 households in Portugal.The economic impact of SIGRE is evaluated through Input–Output Analysis. It was found that SIGRE's activities also have a significant economic impact. For example, their added value are ranked amongst the upper third of the economic activities with highest multiplier effect at national level: this means that for each Euro of value added generated within SIGRE, 1.25 additional € are added to the rest of the economy (multiplier effect of 2.25).Regarding the social impacts of SIGRE, the number of direct jobs associated with the system is estimated to be more than two thousand and three hundred workers. Out of these, 83% are connected to the management of municipal waste packaging (selective collection and sorting), 15% are connected to the management of non-municipal packaging waste and only 2% are connected to the Sociedade Ponto Verde (SPV, green dot society in English) – the management entity responsible for SIGRE.In general terms, the results obtained provide quantitative support to the EEA (2011) suggestion that moving up the waste hierarchy – from landfilling to recycling – creates jobs and boosts the economy.     

Governing trade-offs in ecosystem services and disservices to achieve human–wildlife coexistence

Sustaining wildlife populations, which provide both ecosystem services and disservices, represents a worldwide conservation challenge. The ecosystem services and Ostrom's social–ecological systems frameworks have been adopted across natural and social sciences to characterize benefits from nature. Despite their generalizability, individually they do not include explicit tools for addressing the sustainable management of many wildlife populations. For instance, Ostrom's framework does not specifically address competing perspectives on wildlife, whereas the ecosystem services framework provides a limited representation of the social and governance context wherein such competing perspectives are embedded. We developed a unified social–ecological framework of ecosystem disservices and services (SEEDS) that advances both frameworks by explicitly acknowledging the importance of competing wildlife perspectives embedded in the social and governance contexts. The SEEDS framework emulates the hierarchical structure of Ostrom's social–ecological systems, but adds subsystems reflecting heterogeneous stakeholder views and experiences of wildlife-based services and disservices. To facilitate operationalizing SEEDS and further broader analyses across human–wildlife systems, we devised a list of variables to describe SEEDS subsystems, such as types and level of services and disservices, cost and benefit sharing, and social participation of stakeholders. Steps to implement SEEDS involve engaging local communities and stakeholders to define the subsystems, analyze interactions and outcomes, and identify leverage points and actions to remedy unwanted outcomes. These steps connect SEEDS with other existing approaches in social–ecological research and can guide analyses across systems or within individual systems to provide new insights and management options for sustainable human–wildlife coexistence.     

Enhanced styrene recovery from waste polystyrene pyrolysis using response surface methodology coupled with Box–Behnken design

A work applied response surface methodology coupled with Box–Behnken design (RSM-BBD) has been developed to enhance styrene recovery from waste polystyrene (WPS) through pyrolysis. The relationship between styrene yield and three selected operating parameters (i.e., temperature, heating rate, and carrier gas flow rate) was investigated. A second order polynomial equation was successfully built to describe the process and predict styrene yield under the study conditions. The factors identified as statistically significant to styrene production were: temperature, with a quadratic effect; heating rate, with a linear effect; carrier gas flow rate, with a quadratic effect; interaction between temperature and carrier gas flow rate; and interaction between heating rate and carrier gas flow rate. The optimum conditions for the current system were determined to be at a temperature range of 470–505 °C, a heating rate of 40 °C/min, and a carrier gas flow rate range of 115–140 mL/min. Under such conditions, 64.52% WPS was recovered as styrene, which was 12% more than the highest reported yield for reactors of similar size. It is concluded that RSM-BBD is an effective approach for yield optimization of styrene recovery from WPS pyrolysis.