OPTIMIZATION OF THE HYDROMETRIC NETWORK OPERATION BY A HEURISTIC TRAVELING SALESMAN ALGORITHM1

ABSTRACT: The problem of determining the optimal route to operate a network of hydrometric gauges within a given area is formulated and solved by an original heuristic traveling salesman algorithm. The algorithm used for solving the problem takes into account the variation of station service time, the eight-hour maximum working day, existence of more than one home base, and the budget constraint. The traveling salesman algorithm is used to solve the optima! assignment problem within a one-day time limit, locating a starting base, stations to visit, and the closest home base. The ending base for the previous day becomes the starting base for the next day, and the assignment procedure is repeated. The computation proceeds from day to day, until all the stations in the considered region are serviced. The solution obtained presents the optimal route to operate a network of hydrometric gauges. The optimization procedure has been applied to the Dauphin hydrometric field area in Manitoba.     

Prospects of DLC coating as environment friendly surface treatment process

After first commercialization in 90's, the applications of diamond-like carbon (DLC) have been significantly expanded to tool, automobile parts, machineries and moulds to enhance wear and friction properties. Although DLC has many advantages like high hardness, low friction electrical insulating and chemical stability and has the possible market, its application in the field is still very limited due to the gaps of understanding between end-user and developer of its advantage of costing. Recently, one of the most popular issues in the surface modification is providing the long lasting super-hydrophilic or -hydrophobic properties on the material surface for the outdoor usage. A lot of material loss is caused due to water corrosion which has to do with the flow and contacts of water like fuel cell separator and air conditioner parts. The consequence of development of functional surface based on the hydrophilic or hydrophobic design for the important parts would be really helpful for materials to be cleaner and more energy effective. Here, we first reviewed the DLC technology and then examined the kind of surface modification as well as its merits and disadvantage. We also looked at how we can improve super-hydrophilic and super hydrophobic for the DLC coating layer as well as current status of technology and arts of DLC. In the end, we would like to suggest it as one of the environmental friendly industrial technology.     

Robust Prioritization of Climate Change Adaptation Strategies Using the VIKOR Method with Objective Weights

This study proposes a robust prioritization framework for climate change adaptation strategies under uncertain climate change scenarios, using the VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) method, a multi‐criteria decision‐making approach, together with the Shannon entropy‐based weights. The VIKOR method allows us to find a compromise solution between two decision strategies of maximizing group utility and minimizing individual regret, and the Shannon entropy is used to determine objective weights among multiple climate change scenarios. The proposed methodology was applied to the problem of selecting locations of subwatersheds for reusing treated wastewater (TWW) in a Korean urban watershed. Selected based on the sustainability concept, hydro‐environmental and socioeconomic indicators were used to evaluate the sustainability of TWW reuse under multiple climate change scenarios, using the hydrologic simulation model results and statistical data. Finally, sustainability scores under multiple scenarios were aggregated using the VIKOR together with the Shannon entropy‐based weights for the robust prioritization of adaptation strategies. According to the different levels of regret aversion or affinity, our results for water quality showed different sets of adaptation strategies as the best options, suggesting that our framework would help stakeholders seeking the robust options considering both the utility and regret.     

The Impact of Perceptual and Situational Factors on Environmental Communication: A Study of Citizen Engagement in China

This study applied a situational approach to understanding an environmental problem: PM2.5 (its resulted haze and smog air pollution) in China. Based on a national sample of 374 citizens living in China, it tested a situational model of problem solving and extended it by adding citizens’ environmental engagement behaviour as an immediate consequence of their communicative action. Results of a structural equation modelling analysis supported all the causal links in the conceptual model. Moreover, communicative action significantly mediated the relationship between referent criterion and environmental engagement. Problem recognition, constraint recognition, and involvement recognition did not influence environmental engagement directly, but exerted their significant indirect impact via two key mediators in the model: situational motivation in problem solving and communicative action in problem solving. Theoretical and practical implications of the present study were discussed.     

Application of biochar in advanced oxidation processes: supportive,adsorptive, and catalytic role

Environmental Science and Pollution Research - The advanced oxidation processes (AOPs), especially sulphate radical (SO4•−)–based AOPs (SR-AOPs), have been considered more...     

Assessments of natural and anthropogenic influences on water chemistry in the upper Nakdong River,South Korea

Abstract

The purpose of this study is to evaluate what sources principally affect the chemical compositions in the catchment of the upper Nakdong River, South Korea where bedrock mostly consists of silicates as a natural factor. From October 7^th to 9^th, 2015, thirty-three water samples were collected, including samples from tributaries which run alongside mines. We analyzed the major anions, cations, trace elements and water isotopes of the samples and the analyzed data are divided into four groups by principle component analysis (PCA). We determined that most of the water samples are influenced by water-rock interactions when we consider the PCA results and the chemical weathering equation line. However, six samples have excess concentrations of sulfate and plot below the equation line. These samples were mostly from streams beside a zinc-cadmium smelter, which was also consistent with the PCA results. Samples near populated area could also be separated into a group via domestic pollution. Based on the PCA and chemical results, the chemical compositions of the river can be affected by two anthropogenic inputs: mine wastes and domestic contaminants.     

Market potential of biomethane as alternative transportation fuel in South Korea

This study estimated domestically available energy amount of biomethane including landfill gas (LFG) as a transportation fuel by 2035. The amount of available energy that could be supplied was predicted through four stages of ‘theoretical-’, ‘geographical-’, ‘technical-’, and ‘market potential’ by considering geographical, technical, economic conditions, etc. Energy efficiency and added value of biomethane are largely influenced by the site conditions and the neighboring infrastructures. So, how much of the natural gas used in transportation could be substituted with biomethane was examined by setting limits to the amount of organic wastes generated within urban areas. As a result, the market potential of biomethane including landfill gas was approximately 331 × 10⁶ Nm³/year, corresponding to 25% of the natural gas supply for transportation, which could be replaced by biomethane. Assuming that 2% of natural gas for transportation is replaced by biomethane, it corresponds to 29 × 10⁶ Nm³/year (approximately 9% of market potential of biomethane). However, RFS annual mixing rate may be increased upon introduction and the growth rate of the natural gas supply for transport would be higher than that of market potential of biomethane calculated in this study.     

Characterization of dried sewage sludge for co-firing in coal power plant by using thermal gravimetric analysis

This research studied the characteristics of dried sewage sludge using TGA to co-fire dried sewage sludge with coal in power plants. The sewage sludges that were discharged from Daejeon, Korea were dried and examined fundamental properties to use them as a fuel. Also, the properties of bituminous coal and wood pellet, which are used in domestic coal power plants, were analyzed and compared with them of sewage sludges and non-isothermal analyses of dried sewage sludges were performed at the heating rates of 5, 10, 20, and 30C /min using TG analyzer to investigate the basic combustion characteristics. As a results of these TGA/DTG analyses, sewage sludges showed its primary peak at the temperature of 250–500?°C, which overlapped with main peak of wood and secondary peak at around 500–600?°C, which overlapped with main peak of coals. Also for the interpretation by Friedman method, the activation energies in the section of highest weight loss were 525.16 kJ/mole for dried digested sewage sludge, 544.88 kJ/mole for dried excess sewage sludge, 203.86 kJ/mole for wood pellet and 146.4585 kJ/mole for bituminous coal. The reaction orders for dried digested excess sewage sludge, dried excess sewage sludge, wood pellet and bituminous coal were 28.775, 24.319, 18.398 and 9.1005, respectively, and the frequency factors were 5.89?\(\times \hspace{0.17em}\)10²⁸, 1.65?\(\times \hspace{0.17em}\)10^24,, 9.59?\(\times \hspace{0.17em}\)10¹⁶ and 1.77?\(\times \hspace{0.17em}\)10⁸ for each, respectively.