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النتائج 4411 - 4420 من 7,292
Determinants of load capacity factor in South Korea: does structural change matter? النص الكامل
2022
Abdulmagid Basheer Agila, Taha | Khalifa, Wagdi M. S. | Saint Akadiri, Seyi | Adebayo, Tomiwa Sunday | Altuntaş, Mehmet
By likening biocapacity and ecological footprint, the load capacity factor follows a specified ecological threshold, permitting for an in-depth analysis of ecological damage. It can be seen that as the load capacity factor is reduced, the ecological damage intensifies. Until now, scholars have used carbon dioxide, ecological footprint, nitrogen oxide, sulfur dioxide, and other indices to objectively examine ecological problems. The utilization of these metrics can cause the supply side of ecological concerns to be overlooked. To make up for this weakness, this paper evaluates the impact of structural change and trade globalization on the load capacity factor. The research also considers other drivers of load capacity factors such as economic growth and energy. We utilized the nonparametric such as nonparametric causality and quantile-on-quantile (QQ) regression approaches to scrutinize these interconnections for South Korea between 1970 and 2018. The findings from the QQ approach disclosed that in the majority of the quantiles, the influence of economic growth, structural change, energies (renewable and nonrenewable), and trade globalization mitigate the load capacity factor. Moreover, the nonparametric causality test divulged that in variance and mean, all the independent variables can predict the load capacity factor. Policy proposals for South Korea’s sustainable development are offered based on the findings.
اظهر المزيد [+] اقل [-]Environmental quality and the role of economic policy uncertainty, economic complexity, renewable energy, and energy intensity: the case of G7 countries النص الكامل
2022
Chu, Lan Khanh | Le, Ngoc Thi Minh
This study explores the environmental impacts of economic policy uncertainty, economic complexity, renewable energy, and energy intensity on the countries in the Group of Seven (G7) countries. To this end, the study employs fully modified ordinary least squares and a fixed effects model with Driscoll and Kraay, Rev Econ Stat 80:549–560, (1998) robust standard errors and a panel dataset from 1997 to 2015. The findings demonstrate a long-term relationship between the variables of interest and carbon dioxide emissions and the ecological footprint. Specifically, high energy intensity increases environmental pollution while high economic policy uncertainty and renewable energy reduces environmental degradation. The environmental Kuznet curve of economic complexity and environmental quality holds for G7 countries. Moreover, economic policy uncertainty strongly moderates the environmental effect of renewable energy, economic complexity, and energy intensity. Specifically, although economic policy uncertainty amplifies the beneficial environmental effects of renewable energy and economic complexity, it enlarges the harmful effect of energy intensity on environmental quality. These empirical outcomes allow us to draw useful implications for policy makers to mitigate the environmental degradation.
اظهر المزيد [+] اقل [-]Taguchi optimization of geopolymer concrete produced with rice husk ash and ceramic dust النص الكامل
2022
Memiş, Selçuk | Bılal, Mohamed Ahmed Mohamed
Metakaolin, fly ash, and mostly granulated blast furnace slag (GBFS) are traditionally used in the production of geopolymer. This study, adding to the knowledge base on geopolymer concretes as an alternative to cement mixtures, explored an experimental approach that investigates the use of ceramic dust (CD) and rice husk ash (RHA) with high SiO content instead of GBFS in the production of geopolymers. For this purpose, instead of GBFS, RHA at proportions of 0, 5%, 10%, and 15% and CD at proportions of 0, 10%, 20%, and 30% were used in the production of geopolymer concrete. In addition, groups were determined with a Taguchi L16 matrix with NaOH (an important material in geopolymer production) at 12, 14, 16, and 18 molality. Varying combinations of flow diameter, density, porosity, and water absorption rate were used, and their performance under high temperatures in terms of compressive strength was evaluated. The use of RHA in geopolymer concretes produced using CD and RHA had a negative effect on the flow and water absorption rates. However, the use of CD had a positive effect, and geopolymer concretes with high density and porosity were obtained. In addition, it was determined that strengths > 70 MPa could only be obtained if 5–20% CD were used at 14–16 molality. The resistance of geopolymer concretes to high temperatures is lower than normal concretes. However, when comparing RHA and CD, it was determined that the use of CD would be more effective on geopolymer materials, and special measures should be taken at temperatures > 450 °C.
اظهر المزيد [+] اقل [-]Insights into the nurse effect of a native plant Ficus tikoua on Pb‒Zn tailing wastelands in western Hunan, China النص الكامل
2022
Zhou, Yingru | Sun, Kuangnan | Mi, Ying | Luo, Benxiang | Xiang, Jing | Ma, Taowu
Lead‒zinc (Pb‒Zn) processing and extraction activity generates large volumes of highly toxic and bare tailing (BT) wastelands which poses a potentially extreme risk to the surrounding environment. Revegetation in the Pb‒Zn tailing wastelands is usually considered a beneficial approach. Ficus tikoua is a native vine which can successfully colonize on Maoping Pb‒Zn mine tailing wastelands in western Hunan, China. This study involved examination of the nurse effect of F. tikoua on Pb‒Zn tailing wastelands, to provide insights into the potential mechanism of F. tikoua influencing soil quality and vegetation succession. The vegetation characteristics, nutrient properties, and heavy metal contents of three different types of vegetation patches associated with F. tikoua in Pb‒Zn tailing wastelands, representing different stage of succession, were investigated. The height, coverage, and aboveground and underground biomass of these vegetation patches showed an increasing trend from vegetation patch I (VP-I) to patch III (VP-III). The nutrient pool and chemical properties of these tailing wastelands gradually re-established from BT wasteland to VP-III. From VP-I to VP-III, the total heavy metal contents (i.e., Pb, Zn, Cu, and Cd) and DTPA-extractable Pb, Cu, and Cd contents significantly decreased, while the DTPA-extractable Zn content remained unchanged. Our findings suggested that F. tikoua exerts a distinct nurse plant effect by increasing the essential nutrient content of soil, reducing the available heavy metal content, and subsequently increasing the number of plant species and the biomass. Therefore, F. tikoua may be used as a promising nurse plant for triggering revegetation and phytostabilization of Pb‒Zn tailing wastelands at the initial stage of remediation.
اظهر المزيد [+] اقل [-]Polycyclic aromatic hydrocarbons in coastal sediments of Southern Terengganu, South China Sea, Malaysia: source assessment using diagnostic ratios and multivariate statistic النص الكامل
2022
Pang, Swee Yun | Suratman, Suhaimi | Latif, Mohd Talib | Khan, Md Firoz | Simoneit, Bernd R. T. | Mohd Tahir, Norhayati
Surface sediments along the Southern Terengganu coast (≤7 km from the coast) were analyzed for polycyclic aromatic hydrocarbons (PAHs). The concentrations of 16 USEPA priority polycyclic aromatic hydrocarbons (ΣPAH₁₆) ranged from 2.59 to 155 ng g⁻¹ and their respective alkylated ranged between 8.80 and 24.90 ng g⁻¹. Traces of acephenanthrylene, benzo[c]phenanthrene, thiophenic PAH, and benzonaphthofuran were identified. PAH diagnostic ratios and cross-plots revealed that these sedimentary PAH compounds are derived mainly from pyrogenic sources, primarily from biomass burning and petroleum combustion residues with minor petrogenic input. The high correlations between pyrogenic PAHs to total PAHs (r >0.73, p <0.5), and the Bap/Bep ratio to total PAHs (r = 0.88, p <0.5), suggest that atmospheric deposition and urban runoff are the main deposition pathways. The concentrations of the PAHs in the southern South China Sea fall in the moderate contamination range of 100–1000 ng g⁻¹.
اظهر المزيد [+] اقل [-]Organochlorine pesticides and polychlorinated biphenyls in high mountain lakes, Mexico النص الكامل
2022
García-Solorio, Liliana | Muro, Claudia | De La Rosa, Isaías | Amador-Muñoz, Omar | Ponce-Vélez, Guadalupe
Pollution levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the El Sol and the La Luna alpine lakes. The lakes are located in central Mexico, in the crater of the Nevado de Toluca volcano. The El Sol and the La Luna lakes are extremely relevant in Mexico and in the world because they are recognized as pristine regions and environmental reservoirs. Samples of atmospheric aerosol, sediment, plankton, and Tubifex tubifex (sludge worm) were collected at three different sample locations for three years (2017, 2018, and 2019) at three different times of year, meaning that the weather conditions at the time of sampling were different. Pollutants were analysed by gas chromatography–mass spectrometry with negative chemical ionisation (GC–MS/NCI). Endosulfan was the most frequent and abundant pollutant, showing the highest peaks of all. Atmospheric aerosol revealed Σ₂ = 45 pg/m³, including α and β, while sediment lakes displayed α, β and endosulfan sulfate as Σ₃ = 1963 pg/g, whereas plankton and Tubifex tubifex showed Σ₂ = 576 pg/g and 540 pg/g for α and β respectively. Results of endosulfan ratios (α/β) and (α-β/endosulfan sulfate) suggest that both fresh and old discharges continue to arrive at the lakes. This study shows for the first time the pollution levels of OCP and PCB in high mountain lakes in Mexico. These results that must be considered by policy makers to mitigate their use in the various productive activities of the region.
اظهر المزيد [+] اقل [-]Instantaneous discharge characteristics and its methane ignition mechanism of coal mine rock damage النص الكامل
2022
Li, Min | Lv, Huan | Lu, Yi | Wang, Deming | Shi, Shiliang | Li, Runqiu
The goaf is the main site of gas explosions in coal mines. A large number of accidents indicate that the occurrence of gas explosion in the goaf is related to the deformation and fracture of the goaf roof. An experimental system was constructed to study the instantaneous discharge characteristics and its ignition mechanism caused by rock damage. The research results reveal that different rocks produce avalanche-like dust clouds ejected outward during the fracture process, and the generation process takes an extremely short time. This dust cloud is not caused by rock fragments heated to incandescence because of friction. The electric sparks produced in the process of rock rupture and the appearance of instantaneous discharge are related not only to the quartz content of the rock, but also to the compressive strength of the rock. The piezoelectric effect of the rock becomes the key factor for the strength or the generation of an electric spark. The instantaneous discharge leaded to the collision of high-energy electrons released during the fracture process with air molecules, ionising, and breaking down the air. When the surrounding medium is gas air within the explosion limit, ionisation is formed and causes gas explosions.
اظهر المزيد [+] اقل [-]Electric vehicle routing models and solution algorithms in logistics distribution: A systematic review النص الكامل
2022
Ye, Chong | He, Wenjie | Chen, Hanqi
With the development of green logistics and the promotion of new energy vehicle development policies domestically and abroad, electric vehicles have been put into logistics and distribution as an alternative to traditional fuel vehicles. The Electric Vehicle Routing Problem (EVRP) has attracted widespread attention from the academic community. This paper comprehensively examines the latest research progress on electric vehicle routing models and solution algorithms in logistics and distribution. Firstly briefly introduces EVRP models considering battery losses; secondly, based on the composition of the EVRP objective function and constraints, EVRP models are classified into four types: EVRP considering load and battery life constraints, EVRP with a time window and considering charging strategies, the study of vehicle routing problems for hybrid fleets, and EVRP combined with charging/swapping station location. Then, briefly introduce exact algorithms, traditional heuristics, meta-heuristics, and hybrid algorithms for solving EVRP models. Moreover, it analyzes the main meta-heuristics that are more widely used. Finally, this review points out the development trend of EVRP theoretical methods.
اظهر المزيد [+] اقل [-]Method development, validation, monitoring, seasonal effect and risk assessment of multiclass multi pesticide residues in surface and ground water of new alluvial zone in eastern India النص الكامل
2022
Bhattacharyya, Sudip | Poi, Rajlakshmi | Mandal, Swagata | Baskey Sen, Moni | Hazra, Dipak Kumar | Saha, Supradip | Karmakar, Rajib
A liquid–liquid extraction (LLE) method was validated as per SANTE/12682/2019 guidelines for gas chromatography–mass spectrometric (GC–MS) determination of thirty-six multiclass pesticides in environmental waters. Seasonal (summer, monsoon, and winter) effects on the magnitude of pesticide residues in environmental water (river, pond, and tube well) of six different urban areas of Nadia and North 24 Parganas districts (New alluvial zone, Eastern India) was monitored for subsequent risk assessment. Total 288 water samples (96 each of river, pond, and tube-well) irrespective of locations and seasons were monitored for multiclass multi pesticide residues during the experiment. Each sample (750 mL) was extracted with ethyl acetate/dichloromethane (8:2) liquid–liquid partitioning and filtration (0.22 μm nylon filter paper) and total residue was reconstituted in acetone (1 mL) for GC–MS analysis with developed and validated method resulting satisfactory recovery percentages (77.84–118.15%). The maximum no. of organochlorine (OC) and organophosphorus (OP) pesticide residues were dominated in river and pond water irrespective of seasons and monitoring sites. About 74% of river water samples were found to be contaminated with concerned pesticides in variable magnitudes. Monsoon (July to October) season was highly alarming with the highest presence of total pesticide residues in different types of environmental waters. Risk quotient (RQ) [acute and chronic] was also evaluated in pond and river water as sometimes used for drinking purposes. RQ value (5900) of total endosulfan indicates the highest risk of chronic toxicity to river fishes. Seven water samples from tube-wells were also monitored and found to be contaminated with butachlor and chlorpyriphos in non-significant amounts (< 0.1 ng mL⁻¹), irrespective of seasons and sites, thus safe for consumption.
اظهر المزيد [+] اقل [-]Forecasting carbon emissions due to electricity power generation in Bahrain النص الكامل
2022
Qader, Mohammed Redha | Khan, Shahnawaz | Kamal, Mustafa | ʻUs̲mān, Muḥammad | Haseeb, Mohammad
Global warming and climate change have become one of the most embarrassing and explosive problems/challenges all over the world, especially in third-world countries. It is due to a rapid increase in industrialization and urbanization process that has given the boost to the volume of greenhouse gases (GHGs) emissions. In this regard, carbon dioxide (CO₂) is considered a significant driver of GHGs and is the major contributing factor for global warming. Considering the goal of mitigating environmental pollution, this research has applied multiple methods such as neural network time series nonlinear autoregressive, Gaussian Process Regression, and Holt’s methods for forecasting CO₂ emission. It attempts to forecast the CO₂ emission of Bahrain. These methods are evaluated for performance. The neural network model has the root mean square errors (RMSE) of merely 0.206, while the Gaussian Process Regression Rational Quadratic (GPR-RQ) Model has RMSE of 1.0171, and Holt’s method has RMSE of 1.4096. Therefore, it can be concluded that the neural network time series nonlinear autoregressive model has performed better for forecasting the CO₂ emission in the case of Bahrain.
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