•Used fuels including preheated and unpreheated Jatropha oil, diesel fuel.•Impacts of triple-physical properties of fuel on atomization, breakup, and combustion.•Trilateral correlation of deposits, ...spray characteristics, and engine performance.•Thorough analysis on the relation of accumulated deposits and pollutant emissions.•Dependence of spray penetration and cone angle on formed deposits and fuel properties.
The benefits and advantages of bio-based fuels according to the research results of scientists and researchers related to the stable maintenance and sustainable development for the purpose of harmonizing the environment and life is an indisputable fact. Experimental studies on the use of bio-based fuels for engines in the long term should be thus thoroughly conducted to obtain the fullest results of economic-technical features and emissions, to name just a few. In this paper, a state-of-the-art analysis on the core correlation based on the trilateral relationship of spray characteristics, combustion, and emissions of a high-speed four-stroke diesel engine running on Jatropha oil (JO) in two cases of preheated and unpreheated in comparison to diesel fuel was investigated and carried out. Tests included two phases: (i)-tests of spray characteristics, analysis of combustion and emissions for engine fueled with preheated JO, unpreheated JO, and DF at the first hour and after 300 h of endurance test for engine, (ii)-analysis of formed deposits in the nozzle orifices and piston crown after 300 h of operation. As a result, huge deposits formed in the injector orifices and piston crown based on optical observation by SEM in case of using unpreheated JO as fuel were found, followed by preheated JO and DF. In addition, a sharp increase in spray penetration length and a significant decrease of cone angle for unpreheated JO compared to preheated JO and DF were also indicated, whereas thermal efficiency of the test engine for preheated JO, unpreheated JO, and DF was reduced by respectively 1.68%, 4.38%, and 0.98% after 300 h of operation. For emission data, negative changes such as a more reduction of NOx along with a higher augment of CO, HC, and smoke with unpreheated JO than those of preheated JO and DF were reported. In closing, core correlation as well as trilateral impacts of accumulated deposits, spray characteristics, and combustion were thoroughly demonstrated and deeply analyzed.
For the short-term use of diesel engines, biodiesel can provide a comparable engine performance to that of using fossil diesel fuel. However, some arising problems including the reduction of the ...engine performance, the increase in lacquer deposits, and excessive carbon blacks in the combustion chamber and in the injectors resulting in an increase in the emissions and the damage to the engine have been indicated. Deposits formed inside or outside the injector may have an adverse influence on the engine performance and the fuel injection system. In this study, a review of the formed deposits in the injector of diesel engines fueled with biodiesel was conducted. The physicochemical mechanism of the deposit formation in the injector including injector nozzles, injector holes, and injector tips was mentioned. Moreover, the test-cycles for determining the deposit formation level in the injector were also introduced. Especially, the effects of the key factors such as biodiesel components, temperature, and injector configurations on the formation level of deposits were reviewed, and the utilization of the cativation mechanism in the controlling strategy of the deposits was presented. Besides, the impacts of deposits in the injector on the spray characteristics, combustion, and diesel engine operation process were also referred.
The drastic rise in global warming and the fossil fuel consumption have resulted in destruction of the ecological balance, reduction of the environmental quality, and demotion of the sustainable ...development. The utilization of biofuels have been paid much attention to by researchers and policy makers due to its benefits and indisputable contributions to protect the living environment. Free fatty acid-rich rice bran oil which is unsuitable for food purposes could be a good candidate for biofuel production. Accordingly, rice bran oil-based biofuels (straight oil and its biodiesel) as promising alternative fuels to petrodiesel were reviewed in this article from the sources, components, and physicochemical perspectives. In addition, biodiesel production from rice bran oil using various methods and catalysts was thoroughly detailed. The oxidative stability of rice bran biodiesel as a function of the storage time was also discussed. The application of rice bran oil-based biofuels to diesel engines was completely analyzed and critically discussed based on engine performance, combustion, and emissions characteristics. The effects of using rice bran oil-based biofuels on the lubricating oil degradation, deposit formation, wear, and sound intensity of diesel engines were explained in detail. Finally, the economic aspects of using rice bran oil and its biodiesel as fuels were also assessed. As a conclusion, the blend containing 20% rice bran oil biodiesel and 80% petrodiesel fuel, both in volume, could be the most effective composition considering the techno-economic aspects of diesel engines; meanwhile the remaining blends appeared to be improper for the existing diesel engines.
•Various aspects of biofuels from rice bran oil as alternatives to diesel are reviewed.•Biodiesel production from rice bran oil using various methods is analyzed in detail.•The effects of rice bran oil-based biofuels on the behavior of engines are detailed.•The economic aspects of using rice bran oil and its biodiesel as fuels are assessed.•Blending diesel with 20% rice bran oil biodiesel could lead to promising results.
This study investigated the effects of corruption and economic freedom on corporate leverage. We also evaluated how economic freedom shapes the effect of corruption on corporate leverage. Using a ...sample of Vietnamese firms covering a nine‐year period from 2010 to 2018, we find evidence that increased control of corruption has a significant positive impact on firm leverage, whereas the opposite is true for economic freedom. This effect is robust to alternative measures of control of corruption as well as advanced estimation methods, such as firm‐fixed effects and quantile regressions. Our results also reveal that the positive impact of corruption controls on corporate leverage is more pronounced for firms with high economic freedom. Econometrically, our findings indicate that firms with better control over corruption prefer debt financing, as demonstrated by their higher leverage ratio.
In this study, manganese ferrite-graphene oxide (MFO-GO) nanocomposites were prepared
via
a co-precipitation reaction of Fe
3+
and Mn
2+
ions in a GO suspension. The effects of graphene oxide on the ...physicochemical characteristics, magnetic properties and adsorption activities of the MFO-GO nanocomposites were studied. Methylene blue (MB) and arsenic(
v
) were used in this study as model water pollutants. With an increase in the GO content in the range of 10 wt% to 50 wt%, the removal efficiency for both MB dye and arsenic(
v
) ions was improved. Our adsorption data revealed that the adsorption behavior of MB dye showed good agreement with the Langmuir isotherm model and pseudo-second-order equation, whereas the Freundlich isotherm model was more suitable for simulating the adsorption process of arsenic(
v
) ions on the MFO-GO nanocomposites. In addition, an important role of the GO content in the adsorption mechanisms of both MB dye and arsenic(
v
) ions was found, in which GO nanosheets play a key role in the mechanisms of electrostatic/ionic interactions, oxygen-containing groups and π-π conjugation in the case of the adsorption of MB dye, whereas the role of the GO content is mainly related to the mechanism of electrostatic/ionic interactions in the case of the adsorption of arsenic(
v
). Graphene oxide has the functions of increasing the number of active binding sites comprising oxygen-containing functional groups, reducing the agglomeration of MFO nanoparticles, increasing the number of adsorption sites, and improving the electrostatic/ionic interactions between adsorbents and adsorbates in order to enhance the adsorption performance of cationic organic dyes and/or heavy metal anions from aqueous solutions.
In this study, manganese ferrite-graphene oxide (MFO-GO) nanocomposites were prepared
via
a co-precipitation reaction of Fe
3+
and Mn
2+
ions in a GO suspension.
Nanofluids have gained significant popularity in the field of sustainable and renewable energy systems. The heat transfer capacity of the working fluid has a huge impact on the efficiency of the ...renewable energy system. The addition of a small amount of high thermal conductivity solid nanoparticles to a base fluid improves heat transfer. Even though a large amount of research data is available in the literature, some results are contradictory. Many influencing factors, as well as nonlinearity and refutations, make nanofluid research highly challenging and obstruct its potentially valuable uses. On the other hand, data-driven machine learning techniques would be very useful in nanofluid research for forecasting thermophysical features and heat transfer rate, identifying the most influential factors, and assessing the efficiencies of different renewable energy systems. The primary aim of this review study is to look at the features and applications of different machine learning techniques employed in the nanofluid-based renewable energy system, as well as to reveal new developments in machine learning research. A variety of modern machine learning algorithms for nanofluid-based heat transfer studies in renewable and sustainable energy systems are examined, along with their advantages and disadvantages. Artificial neural networks-based model prediction using contemporary commercial software is simple to develop and the most popular. The prognostic capacity may be further improved by combining a marine predator algorithm, genetic algorithm, swarm intelligence optimization, and other intelligent optimization approaches. In addition to the well-known neural networks and fuzzy- and gene-based machine learning techniques, newer ensemble machine learning techniques such as Boosted regression techniques, K-means, K-nearest neighbor (KNN), CatBoost, and XGBoost are gaining popularity due to their improved architectures and adaptabilities to diverse data types. The regularly used neural networks and fuzzy-based algorithms are mostly black-box methods, with the user having little or no understanding of how they function. This is the reason for concern, and ethical artificial intelligence is required.
This paper investigates the effect of economic uncertainty on the performance of small and medium enterprises (SMEs) over the period 2007–2016. This paper also examines the effects of ownership ...structure on the relation between Economic Uncertainty and firm performance. We find that an increase in economic uncertainty is negatively associated with the performance of SMEs. Our results also reveal that increased economic uncertainty is associated with a lower performance level for state‐owned SMEs, whereas foreign‐owned SMEs can better mitigate the negative impact of on their performance than domestic‐owned firms.
Stigma poses considerable challenges to the mental health of people living with HIV who use drugs (PLHWUD). In this study, we explored factors related to different types of stigma (perceived and ...internalized) attached to layered stigmatizing characters (HIV and drug use) and their mental health influences on PLHWUD. The study used baseline data of an ongoing randomized controlled trial among 241 PLHWUD recruited between March and December 2018 in Vietnam. A structural equation model was used to assess the relationships among different types and layers of stigma and mental health status. Both perceived and internalized drug-related stigma measures were significantly higher than their corresponding HIV-related stigma. HIV-related stigma was negatively associated with mental health status; however, we did not find a significant relationship between drug-related stigma and mental health. Tailored intervention strategies in consideration of types and layers of stigma are needed to address stigma-related challenges faced by PLHWUD.
Microbial fuel cell (MFC) is lauded for its potentials to solve both energy crisis and environmental pollution. Technologically, it offers the capability to harness electricity from the chemical ...energy stored in the organic substrate with no intermediate steps, thereby minimizes the entropic loss due to the inter-conversion of energy. The sciences underneath such MFCs include the electron and proton generation from the metabolic decomposition of the substrate by microbes at the anode, followed by the shuttling of these charges to cathode for electricity generation. While its promising prospects were mutually evinced in the past investigations, the upscaling of MFC in sustaining global energy demands and waste treatments is yet to be put into practice. In this context, the current review summarizes the important knowledge and applications of MFCs, concurrently identifies the technological bottlenecks that restricted its vast implementation. In addition, economic analysis was also performed to provide multiangle perspectives to readers. Succinctly, MFCs are mainly hindered by the slow metabolic kinetics, sluggish transfer of charged particles, and low economic competitiveness when compared to conventional technologies. From these hindering factors, insightful strategies for improved practicality of MFCs were formulated, with potential future research direction being identified too. With proper planning, we are delighted to see the industrialization of MFCs in the near future, which would benefit the entire human race with cleaner energy and the environment.
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•The fundamentals and applications of microbial fuel cells were summarized.•The hindering factors for upscaling of microbial fuel cells were discussed.•Economic analysis for microbial fuel cell technologies was performed.•Insightful strategies to improve microbial fuel cells' practicality were proposed.
This study aimed to measure the exposure of residents to health education messages about non-communicable diseases (NCD)-related risk factors, and activities of village health workers (VHWs) in NCDs ...prevention and control in the mountainous setting of Vietnam. A cross-sectional study was performed in Dap Thanh commune (Ba Che, Quang Ninh province, Vietnam), a mountainous area. There were 151 residents aged 18 years or above recruited for this study. Information regarding exposure to messages about risk factors of NCDs, and activities of VHWs was collected via face-to-face interviews using a structured questionnaire. Multivariate logistic regression was employed to identify associated factors with exposing messages about NCD-related risk factors. The majority of participants heard about messages related to risk factors of NCDs in the last 30 days, from 56.3% (physical inactivity message), 59.6% (diet message), 75.5% (alcohol use message) to 79.5% (smoking message). Radio/television was the most common source of the messages (from 91.8% to 95.8%) and the majority of participants heard these messages from one source (from 77.1% to 80.9%). Most of sample reported the unavailability of VHWs in their locals (53.6%). Among locals having VHWs, health communication and education was the most common service provided (54.3%); however, only 30% received NCD management services. Participants who had other jobs were less likely to hear about diet-related messages (OR = 0.32; 95%CI = 0.11-0.92), and those ever smoking were more likely to hear these messages in the last 30 days (OR = 6.86; 95%CI = 1.06-44.51). People who had diabetes mellitus were more likely to hear physical activity-related messages in the last 30 days (OR = 2.55; 95%CI = 1.20-5.41). Our findings indicated that health communication regarding risk factors of NCDs in mountainous areas in Vietnam was insufficient, and the role of health workers as formal information source was not recognized. Efforts should be made to increase the capacity and involvement of VHWs in health education and NCD prevention in mountainous regions.
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