Journal Articles - Environment and Environmental Protection - 2017

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  • Publication
    Preliminary developing a mathematical model for estimating household solid waste generation rate: the case of Ho Chi Minh City, Vietnam
    ( 2017)
    Le Minh Truong
    ;
    Tran Thu Trang
    ;
    Tran Thi My Dieu
    Solid waste generation rate plays an important role in calculation and design different elements of a municipal solid waste management system of an urban area. The survey was carried out at 644 households living in 6 selected wards of 6 districts in Ho Chi Minh City (HCMC) that have different population densities to determine generation rates and main composition (food refuses and plastic bags) in domestic solid waste. Composition of household solid waste of HCMC determined from this study will help to develop a model to predict solid waste generation rate in the future. It is also found from the study that, in 2015 household solid waste generation rate of HCMC is 0.41 kg/capita/day (SD = 0.313), food refuse generation rate is 0.23 kg/capita/day, plastic bag generation rate is 0.032 kg/ capita/day, and percentages of food refuses and plastic bags in domestic solid wastes of HCMC are 61.63% and 7.67%, respectively. Statistical data indicate that generation rates of household solid waste, food refuses, and plastic bags are inversely proportional to the number of people in a family and directly proportional to the household income. The rank correlation shows no significance between the household solid waste generation rates and the urbanization levels as well as between household solid waste generation rates and days of a week. A linear regression model proposed to determine generation rates of household solid waste, household food refuse, and household plastic bags shows that household size and household income explain only 14.2% of solid waste generation rate (R2 = 0.142) and 11.9% of plastic bag generation rate (R2 = 0.119). Generation rate of food refuse (within the scope of this study) can only be estimated based on household size (R2 = 0.08).
  • Publication
    Correlation between climate change impacts and migration decisions in Vietnamese Mekong Delta
    ( 2017)
    Oanh Le Thi Kim
    ;
    Truong Le Minh
    Climate change poses new risks to human security and causes a new context for migration (CARE, 2009). Sang and Long (2012) showed that the largest source of migrants in Ho Chi Minh City (HCMC) originates from Mekong Delta while (Dun, 2009) demonstrated that environmental issues are important factors promoting migration in this region. To further study the impact of climate change on migration, the study aims at investigating a correlation between the environmental impacts of climate change and migration decisions. Based on 400 interviews with local people in Ben Tre and Dong Thap provinces (highest sources of immigrants in HCMC), statistical analysis (reliability analysis – Cronbach’s alpha and factor analysis – EFA) proves that (1) the impacts of climate change on production activities; (2) the impacts of climate change on the quality of life; (3) the impacts of climate change on environmental quality are factors which have contributed to migration decisions of those suffering from climate change. Correlation analysis results showed that there is a correlation between the impacts of climate change and migration decisions (p <0.05), and the decision to migrate directly proportional to the increase in the influence of climate change.
  • Publication
    Nghiên cứu thực nghiệm việc thay thế môi chất R404A bằng môi chất R407F để tiết kiệm năng lượng và bảo vệ môi tường
    ( 2017)
    Nguyen The Bao
    ;
    Nguyen Duy Tue
    ;
    Do Huy Tuan
    Trong các loại môi chất lạnh dùng thay thế R22, môi chất R404A được sử dụng khá phổ biến trong các hệ thống lạnh nhiệt độ trung bình và thấp tại nước ta. Tuy nhiên, với hệ số GWP=3922 khá cao, môi chất này cũng làm gia tăng hiệu ứng nhà kính nên hiện nay các nước Châu Âu đang tiến hành cắt giảm việc sản xuất loại môi chất này. Do đó, với một hệ số GWP=1824, thấp hơn 50% so với R404A thì môi chất R407F là một trong những môi chất được sử dụng để thay thế R404A. Kết quả thực nghiệm cho thấy rằng, khi thay thế một hệ thống lạnh đang sử dụng R404A bằng R407F thì năng suất lạnh tăng, công nén giảm khoảng 7%, giúp tiết kiệm năng lượng từ 10% trở lên, và làm giảm thời gian làm lạnh sản phẩm mà không cần thay thế các thiết bị chính trong hệ thống lạnh. Tuy nhiên, với lưu lượng khối lượng tuần hoàn thấp hơn 40% so với R404A nên cần cân chỉnh van tiết lưu để phù hợp khi vận hành.