Micro/nanofluids are the recent alternative solutions for cooling lubrication that can be defined... more Micro/nanofluids are the recent alternative solutions for cooling lubrication that can be defined as the fluids containing microparticles or nanoparticles, which own superior lubrication and cooling characteristics. For these reasons, they have gained significant attention in industrial applications, such as automotive, machining, and biomedical industries. In this chapter, the authors mainly present the recent progress and applications of nanofluids in machining processes, as well as some initial researches about microfluids. Nanofluids provide an excellent media in cutting zone for enhancing the thermal conductivity and tribological characteristics. Therefore, they help to enhance the cutting performance by reducing the coefficient of friction, cutting temperature tool wear, and improving the surface quality. Moreover, the application of nanoparticles in vegetable oils, which are inherently nontoxic as well as biodegradable, gives them superior lubrication properties suitable for MQL application, especially for difficult-to-cut materials. The novel green technology definitely brings out many new solutions in machining practice.
Cutting fluids used in the metal machining industry have exerted serious impacts on the environme... more Cutting fluids used in the metal machining industry have exerted serious impacts on the environment and human health. In addition, the very high cutting heat and forces in machining-hardened steels have been a growing concern in the metal cutting field. Hence, new, eco-friendly cooling and lubricating techniques are necessary to study and develop. Minimum quantity lubrication (MQL) and minimum quantity cooling lubrication (MQCL) using nano cutting fluids have been proven as alternative solutions for machining difficult-to cut materials while retaining an environmentally friendly characteristic. Accordingly, this paper aims to analyze and evaluate the hard turning efficiency of 90CrSi (60 ÷ 62 HRC) steel using MQL and MQCL conditions, using Al2O3 and MoS2 nano cutting fluids. The 2k-p experimental design and analysis of variance (ANOVA) were used to study the influence of input parameters including fluid type, lubrication method, nanoparticle type, nanoparticle concentration, cutting...
The SRI is a dedicated team of over 20 researchers working on different aspects of sustainability... more The SRI is a dedicated team of over 20 researchers working on different aspects of sustainability. Adapting to environmental change and governance for sustainability are the Institute's overarching themes. SRI research explores these in interdisciplinary ways, drawing on geography, ecology, sociology, politics, planning, economics and management. Our specialist areas are: sustainable development and environmental change; environmental policy, planning and governance; ecological and environmental economics; business, environment and corporate responsibility; sustainable production and consumption. The Centre for Climate Change Economics and Policy (CCCEP) was established by the University of Leeds and the London School of Economics and Political Science in 2008 to advance public and private action on climate change through innovative, rigorous research. The Centre is funded by the UK Economic and Social Research Council and has five inter-linked research programmes: 1. Developing climate science and economics 2. Climate change governance for a new global deal 3. Adaptation to climate change and human development 4. Governments, markets and climate change mitigation 5. The Munich Re Programme-Evaluating the economics of climate risks and opportunities in the insurance sector More information about the Centre for Climate Change Economics and Policy can be found at: http://www.cccep.ac.uk.
Advances in Microfluidic Technologies for Energy and Environmental Applications, 2020
Recently, there has been growing attention to nanofluids, especially in industry. More and more p... more Recently, there has been growing attention to nanofluids, especially in industry. More and more people nowadays see nanoparticle applications in various fields such as automotive, agriculture, medicine, machining, and so on. The addition of different nanoparticles to fluids has shown enormous advantages, particularly for improving the efficiency and therefore lowering the energy consumption of processes for addressing a wide range of global challenges related with energy and environmental problems. Nanoparticles are of great scientific interest as they are in that nanofluid with unusual effects, and ultra-small sizes will be a new area for researchers and definitely offer novel mechanisms and technologies in the future. In this chapter, the authors will mainly present the characteristics as well as latest advances in applications of nanofluids in machining practices. Nanoparticle additives contribute to reduce friction coefficient, lower the energy consumption, and significantly extend tool life by lowering thermal stress, from which the surface quality of manufactured parts improves. Moreover, the nanoparticle application in some of the green technologies as MQL and MQCL using vegetable oils not only brings out superior cooling and lubricating properties and minimizes the use of cutting fluids, but also creates new solutions for machining, especially for difficult-to-cut materials.
Machining difficult-to-cut materials is one of the increasingly concerned issues in the metalwork... more Machining difficult-to-cut materials is one of the increasingly concerned issues in the metalworking industry. Low machinability and high cutting temperature generated from the contact zone are the main obstacles that need to be solved in order to improve economic and technical efficiency but still have to ensure environmental friendliness. The application of MQL method using nano cutting fluid is one of the suggested solutions to improve the cooling and lubricating performance of pure-MQL for machining difficult-to-cut materials. The main objective of this paper is to investigate the effects of nanofluid MQL (NFMQL) parameters including the fluid type, type of nanoparticles, air pressure and air flow rate on cutting forces and surface roughness in hard milling of 60Si2Mn hardened steel (50–52 HRC). Analysis of variance (ANOVA) was implemented to study the effects of investigated variables on hard machining performance. The most outstanding finding is that the main effects of the in...
Minimum quantity lubrication (MQL) has gained significant attention in various research fields an... more Minimum quantity lubrication (MQL) has gained significant attention in various research fields and industrial applications for its advantages of being environmentally friendly and suitable for sustainable production. The effectiveness of MQL is increasing significantly by using nano cutting fluid, which can be produced by suspending nanoparticles in the based cutting fluid. This study aims to investigate the effects of MoS2 nanoparticle concentration, cutting speed, and feed rate on MQL hard turning of 90CrSi steel in terms of surface roughness and surface microstructure. The Box–Behnken experimental design was used to analyze the influence of input parameters and their interaction effects as well as to find the optimal set of variables. The obtained results prove the improvement of the machinability of carbide tools due to higher cooling and lubricating performance created by MoS2 nanofluid MQL, which contributes to improve the surface quality and reduce the manufacturing cost. The...
In recent years, the application of environmentally friendly cutting fluids in the metal cutting ... more In recent years, the application of environmentally friendly cutting fluids in the metal cutting industry has been a growing concern in all over the world. In this study, the minimum quantity cooling lubrication (MQCL) technique, which uses very small amount of cutting oil, is motivated to apply to the hard milling process of Hardox 500 steel. Further, rice bran oil, a natural biodegradable oil, is used as the base fluid of Al2O3/MoS2 hybrid nanofluid. ANOVA analysis is used to study the influences of nanoparticle concentration, cutting speed, and feed rate on surface roughness. The obtained results indicate that good surface quality is achieved and the cutting speed is significantly increased to 140 m/min (about 2.55–2.80 times higher than the recommended values) due to the better cooling and lubricating effects from MQCL system and Al2O3/MoS2 hybrid nanofluid. Moreover, the microstructure of the machined surface proves the formation of MoS2 tribo film by using Al2O3/MoS2 hybrid na...
The commercial banks (CBs) performance evaluating has been a necessary problem in currently integ... more The commercial banks (CBs) performance evaluating has been a necessary problem in currently integration trend and usually implemented by a committee of experts under criteria selected. Therefore, it is considered as a Multi - Criteria Decision - Making model (MCDM). Nowadays, there have been many researches proposing various standards and models to evaluate and rank CBs. But in Vietnam, the number of studies related to the Vietnamese banking evaluation model have still been limited. As a result, this study develops a multi-criteria decision model integrating Fuzzy Analytical Hierarchy Process (FAHP) and Fuzzy the Technique for Order of Preference by Similarity to Ideal Solution (FTOPSIS). The proposed model has evaluated and ranked five Vietnamese commercial banks including CTG, VCB, BIDV, TCB and MB. The paper revealed their ranks. Besides, the results of the research show that the Analytical Hierarchy Process (AHP) model is suitable for applying it to the process evaluating bank p...
The present work shows the process for MoS2 nanosheet production by liquid N2-queched bulk, a nov... more The present work shows the process for MoS2 nanosheet production by liquid N2-queched bulk, a novel method having highly efficient, green, and facile operation. The produced MoS2 nanoparticles are suspended in minimum quantity cooling lubrication (MQCL)-based fluid to form nanofluid used for the hard milling of AISI D2 steel. The study aims to improve the hard-milling performance assisted by the MQCL technique using MoS2 nanofluid. ANOVA analysis is used to evaluate the effects of three input machining variables, including nanoparticle concentration, cutting speed, and material hardness on cutting forces. The results indicate that the better cooling effect from the principle of the Ranque–Hilsch vortex tube of the MQCL device combined with the better lubricating performance from MoS2 nanofluid brings out the sustainable alternative solution for machining difficult-to-cut material. Moreover, the experimental results provide the technical guides for the selection of proper values of n...
VNU Journal of Science: Computer Science and Communication Engineering, 2018
In the clinical diagnosis of epilepsy using electroencephalogram (EEG) data, an accurate automati... more In the clinical diagnosis of epilepsy using electroencephalogram (EEG) data, an accurate automatic epileptic spikes detection system is highly useful and meaningful in that the conventional manual process is not only very tedious and time-consuming, but also subjective since it depends on the knowledge and experience of the doctors. In this paper, motivated by significant advantages and lots of achieved successes of deep learning in data mining, we apply Deep Belief Network (DBN), which is one of the breakthrough models laid the foundation for deep learning, to detect epileptic spikes in EEG data. It is really useful in practice because the promising quality evaluation of the spike detection system is higher than $90$\%. In particular, to construct accurate detection model for non-spikes and spikes, a new set of detailed features of epileptic spikes is proposed. These features were then fed to the DBN which is modified from a generative model into a discriminative model to aim ...
Hard machining has gained much attention to be an alternative solution for many traditional finis... more Hard machining has gained much attention to be an alternative solution for many traditional finish grinding operations due to high productivity, ease to adapt to complex part contours, the elimination of cutting fluids, good surface quality, and the reduction of machine tool investment. However, the enormous amount of heat generated from the cutting zone always requires the high-grade inserts and limits the cutting conditions. The MQL technique with nanofluids assisted for hard machining helps to improve the cutting performance while ensuring environmentally friendly characteristics. This paper focuses on the development of MQL technique by adding Al2O3 and MoS2 nanoparticles to the base fluids (soybean oil and water-based emulsion) for the hard turning of 90CrSi steel (60÷62 HRC). The analysis of variance (ANOVA) is used to evaluate the performance of MQL parameters in terms of cutting forces and surface roughness. The study reveals that a better performance of coated carbide inser...
Asia-Pacific journal of public health, Jan 26, 2018
Water hygiene, sanitation, and proper management of health care wastes at health care facilities ... more Water hygiene, sanitation, and proper management of health care wastes at health care facilities are important in preventing infections and improving health and the environment. This article describes the access to safe water and sanitation facilities and the disposal of medical wastes at commune health centers (CHCs) in Vietnam. Data was extracted from the 2015 World Bank Vietnam District and Commune Health Facility Survey. Bivariate and multivariate logistic regression was applied to identify associations of CHCs' access to improved water and sanitation and their medical waste management. Overall, 72.76% CHCs had access to both improved water and sanitation facilities, and better access was found in the richest communes. Rural CHCs had higher prevalence of appropriate wastewater treatment. The majority of CHCs combusted medical solid wastes by specialized incinerations, contracted out with sanitation companies, or transported them to district health centers. However, the data ...
The Law on Tobacco Control and the Law on Advertisement prohibit the advertising of any tobacco p... more The Law on Tobacco Control and the Law on Advertisement prohibit the advertising of any tobacco product in Vietnam. Tobacco promotion and marketing are alsostrictly prohibited. However, the violation of tobacco adverting and promotion is still common in Vietnam. This article aims at describing the exposure to tobacco advertising and promotion among the population aged 15+ years in Vietnam based on the data from the Global Adult Tobacco Survey 2015 from the view of the community, identifying any possible associations between the exposure to tobacco advertising and promotion and other individual factors, and discussing its possible public health implications. A cross-sectional study with the nationwide scale. Secondary data from the Global Adult Tobacco Survey 2015 was explored and analyzed. Chi-square test and multivariate logistic regressions were applied in the data analysis. The most common type of adults' exposure to tobacco advertising and promotion was points of sale (8.6%)...
Journal of Polymer Science: Polymer Physics Edition, 1985
Solutions of polystyrene of molecular weight 4.5 × 106 and 8.4 × 106 in mixed solvents of carbon ... more Solutions of polystyrene of molecular weight 4.5 × 106 and 8.4 × 106 in mixed solvents of carbon tetrachloride/methanol were filtered through track-etched mica membranes at low membrane velocities. The unperturbed hydrodynamic radius of the polymer was always larger than the pore radius. The reflection coefficient σ, defined as the fraction of polymer held back by the membrane, was determined from material balances as a function of solvent flow rate per pore q, volume percent CCl4 of the solvent, and polymer concentration C0. In the dilute region (C0 C*) σ decreased significantly as C0 was increased.
Journal of Polymer Science: Polymer Physics Edition, 1984
Dilute solutions of polystyrene (molecular weight 1 x 105-2x lo7) in a mixed solvent of 90% carbo... more Dilute solutions of polystyrene (molecular weight 1 x 105-2x lo7) in a mixed solvent of 90% carbon tetrachloride-10% methanol were filtered through tracketched porous mica membranes. The reflection coefficient u, defined as the fraction of polymer held back by the membrane, was measured as a function of polymer size r,, pore radius r,,, and solvent flow rate q through each pore. Polymer size was characterized by the StokeEinstein radius, as determined from diffusion coefficients measured by quasielastic light scattering, and chain relaxation times T were estimated from measured intrinsic viscosities. In the case of chains whose unperturbed radius was smaller than the pore, u depended on the ratio r J r , in the manner predicted by a hard-sphere theory, as long as-j~ < < 1, where-j is the mean rate of strain of solvent at the pore entrance. However, when the polymer chains exceeded the pore in size, u depended on flow rate and decreased from almost unity, at small q, toward zero at high q. The relationship between u and q was nearly independent of polymer and pore size, consistent with a theory based on scaling concepts of how polymer chains deform at the entrance of a pore, but the reduction in u as q increased was very gradual and did not exhibit the sharp transition predicted by the theory. We were able to empirically correlate all the data for (T when r, > r,, by a single similarity variable 8 = (rJro)/(yT)"-(rJro)13nq-"; a leastsquares fit gave n = 0.33, showing that u is insensitive to polymer size for large chains.
It is indicated that children are involuntarily exposed to secondhand smoke from adults, mainly a... more It is indicated that children are involuntarily exposed to secondhand smoke from adults, mainly at their home environment. This study aimed at describing the effectiveness of the school-based intervention to decrease the in-home smoking situation of adults so as to decrease children's exposure to secondhand smoke at home during the year 2011-2012 in a rural district in Hanoi, Viet Nam. This school-based intervention program (intervention and control group) involved 804 children aged 8 to 11 years from August 2011 to May 2012 in a rural district of Hanoi, Viet Nam. Children were taught in class about the harmful effects of secondhand smoke and about how to negotiate with fathers not to smoke in-home. Then children applied what they learnt, including staying away from secondhand smoke and persuading fathers not to smoke in-home in order to decrease children's exposure to secondhand smoke. Chi square test, t-test and multinominal logistic regression were applied in data analysis. The results showed that children's reported their father's in-home smoking decreased from 83.0% pre-intervention to 59.8% post-intervention (p < 0.001) in the intervention school while no change 864
This study aims to characterize household trends in access to improved water sources and sanitato... more This study aims to characterize household trends in access to improved water sources and sanitaton in Chi Linh Town, Hai Duong Province, Vietnam, and to identify factors affecting those trends. Method: Data were extracted from the Chi Linh Health and Demographic Surveillance System (CHILILAB HDSS) database from 2004-2014, which included household access to improved water sources, household access to improved sanitation, and household demographic data. Descriptive statistical analysis and multinominal logistic regression were used. The results showed that over a 10-year period (2004-2014), the proportion of households with access to improved water and improved sanitation increased by 3.7% and 28.3%, respectively. As such, the 2015 Millennium Development Goal targets for safe drinking water and basic sanitation were met. However, 13.5% of households still had unimproved water and sanitation. People who are retired, work in trade or services, or other occupations were 1.49, 1.97, and 1.34 times more likely to have access to improved water and sanitation facilities than farming households, respectively (p < 0.001). Households living in urban areas were 1.84 times more likely than those living in rural areas to have access to improved water sources and improved sanitation facilities (OR =1.84; 95% CI = 1.73-1.96). Non-poor households were 2.12 times more likely to have access to improved water sources and 881 AIMS Public Health Volume 3, Issue 4, 880-890. improved sanitation facilities compared to the poor group (OR = 2.12; 95% CI = 2.00-2.25). More efforts are required to increase household access to both improved water and sanitation in Chi Linh Town, focusing on the 13.5% of households currently without access. Similar to situations observed elsewhere in Vietnam and other low-and middle-income countries, there is a need to address socioeconomic factors that are associated with inadequate access to improved water sources and sanitation facilities.
Evidence shows that tobacco advertising and promotion activities may increase tobacco consumption... more Evidence shows that tobacco advertising and promotion activities may increase tobacco consumption and usage, especially in youth. Despite the regulation on prohibiting advertisement of any tobacco product, tobacco advertisement and promotion activities are still common in Vietnam. This article presents current exposure to tobacco advertising and promotion (TAP) among school children aged 13 to 15 years in Vietnam in 2014 and potential influencing factors. Data from the Global Youth Tobacco Survey 2014 in Vietnam covering 3,430 school aged children were used. Both descriptive and analytical statistics were carried out with Stata 13 statistical software. Binary logistic regression was applied to explain the exposure to TAP among youth and examine relationships with individual factors. A significance level of p<0.05 and sampling weights were used in all of the computations. In the past 30 days, 48.6% of the students experienced exposure to at least 1 type of tobacco advertising or promotion. Wearing or otherwise using products related to tobacco was the most exposure TAP type reported by students (22.3%). The internet (22.1), points of sales (19.2) and social events (11.5) were three places that students aged 13-15 frequently were exposed to TAP. Binary logistic results showed that gender (female vs male) (OR = 0.61, 95%CI: 0.52-0.71), susceptibility to smoking (OR = 2.12, 95%CI: 1.53-2.92), closest friends' smoked (OR = 1.43, 95%CI: 1.2-1.7) and parents smoking status (OR = 2.83, 95%CI: 1.6-5.01) were significantly associated with TAP exposure among school-aged children. The research findings should contribute to effective implementation of measures for preventing and controlling tobacco use among students aged 13-15 in Viet Nam.
Comprehensive bans on tobacco advertising and promotion were introduced through tobacco control l... more Comprehensive bans on tobacco advertising and promotion were introduced through tobacco control legislation in Viet Nam, but it has been established that violations of the bans are very common. This study was conducted to explore the trend in violations of bans on tobacco advertising and promotion at points of sale in Viet Nam in the past six years and to explore any differences in the violation situations before and after the Law on Tobacco Control came into effect on 1st May 2013. Quantitative data were collected through observation of violations of the bans on tobacco advertising and promotion at points of sale in 10 provinces throughout Viet Nam in four survey rounds (2009, 2010, 2011, and 2015). Variation in violation prevalence over time was examined by chi-square test using a Bonferini method. Binary logistic regression was employed to identify the factors that may have influences on different types of violation. A level of significance of p<0.05 was used for all tests in this article. The most common form of violation was the display of more than one pack/one carton of a cigarette brand. Violation of bans on tobacco advertising increased while violations on promotion ban and on displaying tobacco decreased through time. Some factors associated with the tobacco advertising and promotion bans included surveyed years, types of points of sale, regions and areas where the points of sale were located. The enforcement of the bans did not improve even after the issuance and the enactment of the Law on Tobacco Control. This suggests that the monitoring and enforcement of bans on tobacco advertising and promotion at points of sale should be strengthened. Penalties should be strictly applied for violators as indicated in the current tobacco control legislation.
Journal of Mechanics Engineering and Automation, 2016
The application of cutting fluids in machining brings out many benefits, but their use is accompa... more The application of cutting fluids in machining brings out many benefits, but their use is accompanied by health and enviroment hazards. MQL (Minimum Quantity Lubricant) has become a preciously alternative solution for lubrication against dry machinning and flood cooling lubricant, and this is a step toward green machining. This paper presents a comprehensively experiemental study on investigation of MQL performance in hard milling of S60C steel for multiple responses, including surface quality, cutting forces and tool wear. Compared to dry milling, even-enhanced surfaces finish quality, 20% less cutting force (F t) and almost 112% prolonged tool lifetime are achieved by using MQL with 5% Emulsion in hard milling. In addition, this study compared the performances of MQL milling by using 5% Emulsion to the peanut oil completely harmless to the enviroment. This encouraging result, therefore, reveals that the MQL-employed hard milling can enable significant improvement in productivity, product quality, and overall machining economy even after covering the additional cost of designing and implementing MQL system. Moreover, this study also shows the limitation of peanut oils employed in MQL and proposes the further research in novel additives to enhance the performance of cooling lubricant for vegetable oils.
Micro/nanofluids are the recent alternative solutions for cooling lubrication that can be defined... more Micro/nanofluids are the recent alternative solutions for cooling lubrication that can be defined as the fluids containing microparticles or nanoparticles, which own superior lubrication and cooling characteristics. For these reasons, they have gained significant attention in industrial applications, such as automotive, machining, and biomedical industries. In this chapter, the authors mainly present the recent progress and applications of nanofluids in machining processes, as well as some initial researches about microfluids. Nanofluids provide an excellent media in cutting zone for enhancing the thermal conductivity and tribological characteristics. Therefore, they help to enhance the cutting performance by reducing the coefficient of friction, cutting temperature tool wear, and improving the surface quality. Moreover, the application of nanoparticles in vegetable oils, which are inherently nontoxic as well as biodegradable, gives them superior lubrication properties suitable for MQL application, especially for difficult-to-cut materials. The novel green technology definitely brings out many new solutions in machining practice.
Cutting fluids used in the metal machining industry have exerted serious impacts on the environme... more Cutting fluids used in the metal machining industry have exerted serious impacts on the environment and human health. In addition, the very high cutting heat and forces in machining-hardened steels have been a growing concern in the metal cutting field. Hence, new, eco-friendly cooling and lubricating techniques are necessary to study and develop. Minimum quantity lubrication (MQL) and minimum quantity cooling lubrication (MQCL) using nano cutting fluids have been proven as alternative solutions for machining difficult-to cut materials while retaining an environmentally friendly characteristic. Accordingly, this paper aims to analyze and evaluate the hard turning efficiency of 90CrSi (60 ÷ 62 HRC) steel using MQL and MQCL conditions, using Al2O3 and MoS2 nano cutting fluids. The 2k-p experimental design and analysis of variance (ANOVA) were used to study the influence of input parameters including fluid type, lubrication method, nanoparticle type, nanoparticle concentration, cutting...
The SRI is a dedicated team of over 20 researchers working on different aspects of sustainability... more The SRI is a dedicated team of over 20 researchers working on different aspects of sustainability. Adapting to environmental change and governance for sustainability are the Institute's overarching themes. SRI research explores these in interdisciplinary ways, drawing on geography, ecology, sociology, politics, planning, economics and management. Our specialist areas are: sustainable development and environmental change; environmental policy, planning and governance; ecological and environmental economics; business, environment and corporate responsibility; sustainable production and consumption. The Centre for Climate Change Economics and Policy (CCCEP) was established by the University of Leeds and the London School of Economics and Political Science in 2008 to advance public and private action on climate change through innovative, rigorous research. The Centre is funded by the UK Economic and Social Research Council and has five inter-linked research programmes: 1. Developing climate science and economics 2. Climate change governance for a new global deal 3. Adaptation to climate change and human development 4. Governments, markets and climate change mitigation 5. The Munich Re Programme-Evaluating the economics of climate risks and opportunities in the insurance sector More information about the Centre for Climate Change Economics and Policy can be found at: http://www.cccep.ac.uk.
Advances in Microfluidic Technologies for Energy and Environmental Applications, 2020
Recently, there has been growing attention to nanofluids, especially in industry. More and more p... more Recently, there has been growing attention to nanofluids, especially in industry. More and more people nowadays see nanoparticle applications in various fields such as automotive, agriculture, medicine, machining, and so on. The addition of different nanoparticles to fluids has shown enormous advantages, particularly for improving the efficiency and therefore lowering the energy consumption of processes for addressing a wide range of global challenges related with energy and environmental problems. Nanoparticles are of great scientific interest as they are in that nanofluid with unusual effects, and ultra-small sizes will be a new area for researchers and definitely offer novel mechanisms and technologies in the future. In this chapter, the authors will mainly present the characteristics as well as latest advances in applications of nanofluids in machining practices. Nanoparticle additives contribute to reduce friction coefficient, lower the energy consumption, and significantly extend tool life by lowering thermal stress, from which the surface quality of manufactured parts improves. Moreover, the nanoparticle application in some of the green technologies as MQL and MQCL using vegetable oils not only brings out superior cooling and lubricating properties and minimizes the use of cutting fluids, but also creates new solutions for machining, especially for difficult-to-cut materials.
Machining difficult-to-cut materials is one of the increasingly concerned issues in the metalwork... more Machining difficult-to-cut materials is one of the increasingly concerned issues in the metalworking industry. Low machinability and high cutting temperature generated from the contact zone are the main obstacles that need to be solved in order to improve economic and technical efficiency but still have to ensure environmental friendliness. The application of MQL method using nano cutting fluid is one of the suggested solutions to improve the cooling and lubricating performance of pure-MQL for machining difficult-to-cut materials. The main objective of this paper is to investigate the effects of nanofluid MQL (NFMQL) parameters including the fluid type, type of nanoparticles, air pressure and air flow rate on cutting forces and surface roughness in hard milling of 60Si2Mn hardened steel (50–52 HRC). Analysis of variance (ANOVA) was implemented to study the effects of investigated variables on hard machining performance. The most outstanding finding is that the main effects of the in...
Minimum quantity lubrication (MQL) has gained significant attention in various research fields an... more Minimum quantity lubrication (MQL) has gained significant attention in various research fields and industrial applications for its advantages of being environmentally friendly and suitable for sustainable production. The effectiveness of MQL is increasing significantly by using nano cutting fluid, which can be produced by suspending nanoparticles in the based cutting fluid. This study aims to investigate the effects of MoS2 nanoparticle concentration, cutting speed, and feed rate on MQL hard turning of 90CrSi steel in terms of surface roughness and surface microstructure. The Box–Behnken experimental design was used to analyze the influence of input parameters and their interaction effects as well as to find the optimal set of variables. The obtained results prove the improvement of the machinability of carbide tools due to higher cooling and lubricating performance created by MoS2 nanofluid MQL, which contributes to improve the surface quality and reduce the manufacturing cost. The...
In recent years, the application of environmentally friendly cutting fluids in the metal cutting ... more In recent years, the application of environmentally friendly cutting fluids in the metal cutting industry has been a growing concern in all over the world. In this study, the minimum quantity cooling lubrication (MQCL) technique, which uses very small amount of cutting oil, is motivated to apply to the hard milling process of Hardox 500 steel. Further, rice bran oil, a natural biodegradable oil, is used as the base fluid of Al2O3/MoS2 hybrid nanofluid. ANOVA analysis is used to study the influences of nanoparticle concentration, cutting speed, and feed rate on surface roughness. The obtained results indicate that good surface quality is achieved and the cutting speed is significantly increased to 140 m/min (about 2.55–2.80 times higher than the recommended values) due to the better cooling and lubricating effects from MQCL system and Al2O3/MoS2 hybrid nanofluid. Moreover, the microstructure of the machined surface proves the formation of MoS2 tribo film by using Al2O3/MoS2 hybrid na...
The commercial banks (CBs) performance evaluating has been a necessary problem in currently integ... more The commercial banks (CBs) performance evaluating has been a necessary problem in currently integration trend and usually implemented by a committee of experts under criteria selected. Therefore, it is considered as a Multi - Criteria Decision - Making model (MCDM). Nowadays, there have been many researches proposing various standards and models to evaluate and rank CBs. But in Vietnam, the number of studies related to the Vietnamese banking evaluation model have still been limited. As a result, this study develops a multi-criteria decision model integrating Fuzzy Analytical Hierarchy Process (FAHP) and Fuzzy the Technique for Order of Preference by Similarity to Ideal Solution (FTOPSIS). The proposed model has evaluated and ranked five Vietnamese commercial banks including CTG, VCB, BIDV, TCB and MB. The paper revealed their ranks. Besides, the results of the research show that the Analytical Hierarchy Process (AHP) model is suitable for applying it to the process evaluating bank p...
The present work shows the process for MoS2 nanosheet production by liquid N2-queched bulk, a nov... more The present work shows the process for MoS2 nanosheet production by liquid N2-queched bulk, a novel method having highly efficient, green, and facile operation. The produced MoS2 nanoparticles are suspended in minimum quantity cooling lubrication (MQCL)-based fluid to form nanofluid used for the hard milling of AISI D2 steel. The study aims to improve the hard-milling performance assisted by the MQCL technique using MoS2 nanofluid. ANOVA analysis is used to evaluate the effects of three input machining variables, including nanoparticle concentration, cutting speed, and material hardness on cutting forces. The results indicate that the better cooling effect from the principle of the Ranque–Hilsch vortex tube of the MQCL device combined with the better lubricating performance from MoS2 nanofluid brings out the sustainable alternative solution for machining difficult-to-cut material. Moreover, the experimental results provide the technical guides for the selection of proper values of n...
VNU Journal of Science: Computer Science and Communication Engineering, 2018
In the clinical diagnosis of epilepsy using electroencephalogram (EEG) data, an accurate automati... more In the clinical diagnosis of epilepsy using electroencephalogram (EEG) data, an accurate automatic epileptic spikes detection system is highly useful and meaningful in that the conventional manual process is not only very tedious and time-consuming, but also subjective since it depends on the knowledge and experience of the doctors. In this paper, motivated by significant advantages and lots of achieved successes of deep learning in data mining, we apply Deep Belief Network (DBN), which is one of the breakthrough models laid the foundation for deep learning, to detect epileptic spikes in EEG data. It is really useful in practice because the promising quality evaluation of the spike detection system is higher than $90$\%. In particular, to construct accurate detection model for non-spikes and spikes, a new set of detailed features of epileptic spikes is proposed. These features were then fed to the DBN which is modified from a generative model into a discriminative model to aim ...
Hard machining has gained much attention to be an alternative solution for many traditional finis... more Hard machining has gained much attention to be an alternative solution for many traditional finish grinding operations due to high productivity, ease to adapt to complex part contours, the elimination of cutting fluids, good surface quality, and the reduction of machine tool investment. However, the enormous amount of heat generated from the cutting zone always requires the high-grade inserts and limits the cutting conditions. The MQL technique with nanofluids assisted for hard machining helps to improve the cutting performance while ensuring environmentally friendly characteristics. This paper focuses on the development of MQL technique by adding Al2O3 and MoS2 nanoparticles to the base fluids (soybean oil and water-based emulsion) for the hard turning of 90CrSi steel (60÷62 HRC). The analysis of variance (ANOVA) is used to evaluate the performance of MQL parameters in terms of cutting forces and surface roughness. The study reveals that a better performance of coated carbide inser...
Asia-Pacific journal of public health, Jan 26, 2018
Water hygiene, sanitation, and proper management of health care wastes at health care facilities ... more Water hygiene, sanitation, and proper management of health care wastes at health care facilities are important in preventing infections and improving health and the environment. This article describes the access to safe water and sanitation facilities and the disposal of medical wastes at commune health centers (CHCs) in Vietnam. Data was extracted from the 2015 World Bank Vietnam District and Commune Health Facility Survey. Bivariate and multivariate logistic regression was applied to identify associations of CHCs' access to improved water and sanitation and their medical waste management. Overall, 72.76% CHCs had access to both improved water and sanitation facilities, and better access was found in the richest communes. Rural CHCs had higher prevalence of appropriate wastewater treatment. The majority of CHCs combusted medical solid wastes by specialized incinerations, contracted out with sanitation companies, or transported them to district health centers. However, the data ...
The Law on Tobacco Control and the Law on Advertisement prohibit the advertising of any tobacco p... more The Law on Tobacco Control and the Law on Advertisement prohibit the advertising of any tobacco product in Vietnam. Tobacco promotion and marketing are alsostrictly prohibited. However, the violation of tobacco adverting and promotion is still common in Vietnam. This article aims at describing the exposure to tobacco advertising and promotion among the population aged 15+ years in Vietnam based on the data from the Global Adult Tobacco Survey 2015 from the view of the community, identifying any possible associations between the exposure to tobacco advertising and promotion and other individual factors, and discussing its possible public health implications. A cross-sectional study with the nationwide scale. Secondary data from the Global Adult Tobacco Survey 2015 was explored and analyzed. Chi-square test and multivariate logistic regressions were applied in the data analysis. The most common type of adults' exposure to tobacco advertising and promotion was points of sale (8.6%)...
Journal of Polymer Science: Polymer Physics Edition, 1985
Solutions of polystyrene of molecular weight 4.5 × 106 and 8.4 × 106 in mixed solvents of carbon ... more Solutions of polystyrene of molecular weight 4.5 × 106 and 8.4 × 106 in mixed solvents of carbon tetrachloride/methanol were filtered through track-etched mica membranes at low membrane velocities. The unperturbed hydrodynamic radius of the polymer was always larger than the pore radius. The reflection coefficient σ, defined as the fraction of polymer held back by the membrane, was determined from material balances as a function of solvent flow rate per pore q, volume percent CCl4 of the solvent, and polymer concentration C0. In the dilute region (C0 C*) σ decreased significantly as C0 was increased.
Journal of Polymer Science: Polymer Physics Edition, 1984
Dilute solutions of polystyrene (molecular weight 1 x 105-2x lo7) in a mixed solvent of 90% carbo... more Dilute solutions of polystyrene (molecular weight 1 x 105-2x lo7) in a mixed solvent of 90% carbon tetrachloride-10% methanol were filtered through tracketched porous mica membranes. The reflection coefficient u, defined as the fraction of polymer held back by the membrane, was measured as a function of polymer size r,, pore radius r,,, and solvent flow rate q through each pore. Polymer size was characterized by the StokeEinstein radius, as determined from diffusion coefficients measured by quasielastic light scattering, and chain relaxation times T were estimated from measured intrinsic viscosities. In the case of chains whose unperturbed radius was smaller than the pore, u depended on the ratio r J r , in the manner predicted by a hard-sphere theory, as long as-j~ < < 1, where-j is the mean rate of strain of solvent at the pore entrance. However, when the polymer chains exceeded the pore in size, u depended on flow rate and decreased from almost unity, at small q, toward zero at high q. The relationship between u and q was nearly independent of polymer and pore size, consistent with a theory based on scaling concepts of how polymer chains deform at the entrance of a pore, but the reduction in u as q increased was very gradual and did not exhibit the sharp transition predicted by the theory. We were able to empirically correlate all the data for (T when r, > r,, by a single similarity variable 8 = (rJro)/(yT)"-(rJro)13nq-"; a leastsquares fit gave n = 0.33, showing that u is insensitive to polymer size for large chains.
It is indicated that children are involuntarily exposed to secondhand smoke from adults, mainly a... more It is indicated that children are involuntarily exposed to secondhand smoke from adults, mainly at their home environment. This study aimed at describing the effectiveness of the school-based intervention to decrease the in-home smoking situation of adults so as to decrease children's exposure to secondhand smoke at home during the year 2011-2012 in a rural district in Hanoi, Viet Nam. This school-based intervention program (intervention and control group) involved 804 children aged 8 to 11 years from August 2011 to May 2012 in a rural district of Hanoi, Viet Nam. Children were taught in class about the harmful effects of secondhand smoke and about how to negotiate with fathers not to smoke in-home. Then children applied what they learnt, including staying away from secondhand smoke and persuading fathers not to smoke in-home in order to decrease children's exposure to secondhand smoke. Chi square test, t-test and multinominal logistic regression were applied in data analysis. The results showed that children's reported their father's in-home smoking decreased from 83.0% pre-intervention to 59.8% post-intervention (p < 0.001) in the intervention school while no change 864
This study aims to characterize household trends in access to improved water sources and sanitato... more This study aims to characterize household trends in access to improved water sources and sanitaton in Chi Linh Town, Hai Duong Province, Vietnam, and to identify factors affecting those trends. Method: Data were extracted from the Chi Linh Health and Demographic Surveillance System (CHILILAB HDSS) database from 2004-2014, which included household access to improved water sources, household access to improved sanitation, and household demographic data. Descriptive statistical analysis and multinominal logistic regression were used. The results showed that over a 10-year period (2004-2014), the proportion of households with access to improved water and improved sanitation increased by 3.7% and 28.3%, respectively. As such, the 2015 Millennium Development Goal targets for safe drinking water and basic sanitation were met. However, 13.5% of households still had unimproved water and sanitation. People who are retired, work in trade or services, or other occupations were 1.49, 1.97, and 1.34 times more likely to have access to improved water and sanitation facilities than farming households, respectively (p < 0.001). Households living in urban areas were 1.84 times more likely than those living in rural areas to have access to improved water sources and improved sanitation facilities (OR =1.84; 95% CI = 1.73-1.96). Non-poor households were 2.12 times more likely to have access to improved water sources and 881 AIMS Public Health Volume 3, Issue 4, 880-890. improved sanitation facilities compared to the poor group (OR = 2.12; 95% CI = 2.00-2.25). More efforts are required to increase household access to both improved water and sanitation in Chi Linh Town, focusing on the 13.5% of households currently without access. Similar to situations observed elsewhere in Vietnam and other low-and middle-income countries, there is a need to address socioeconomic factors that are associated with inadequate access to improved water sources and sanitation facilities.
Evidence shows that tobacco advertising and promotion activities may increase tobacco consumption... more Evidence shows that tobacco advertising and promotion activities may increase tobacco consumption and usage, especially in youth. Despite the regulation on prohibiting advertisement of any tobacco product, tobacco advertisement and promotion activities are still common in Vietnam. This article presents current exposure to tobacco advertising and promotion (TAP) among school children aged 13 to 15 years in Vietnam in 2014 and potential influencing factors. Data from the Global Youth Tobacco Survey 2014 in Vietnam covering 3,430 school aged children were used. Both descriptive and analytical statistics were carried out with Stata 13 statistical software. Binary logistic regression was applied to explain the exposure to TAP among youth and examine relationships with individual factors. A significance level of p<0.05 and sampling weights were used in all of the computations. In the past 30 days, 48.6% of the students experienced exposure to at least 1 type of tobacco advertising or promotion. Wearing or otherwise using products related to tobacco was the most exposure TAP type reported by students (22.3%). The internet (22.1), points of sales (19.2) and social events (11.5) were three places that students aged 13-15 frequently were exposed to TAP. Binary logistic results showed that gender (female vs male) (OR = 0.61, 95%CI: 0.52-0.71), susceptibility to smoking (OR = 2.12, 95%CI: 1.53-2.92), closest friends' smoked (OR = 1.43, 95%CI: 1.2-1.7) and parents smoking status (OR = 2.83, 95%CI: 1.6-5.01) were significantly associated with TAP exposure among school-aged children. The research findings should contribute to effective implementation of measures for preventing and controlling tobacco use among students aged 13-15 in Viet Nam.
Comprehensive bans on tobacco advertising and promotion were introduced through tobacco control l... more Comprehensive bans on tobacco advertising and promotion were introduced through tobacco control legislation in Viet Nam, but it has been established that violations of the bans are very common. This study was conducted to explore the trend in violations of bans on tobacco advertising and promotion at points of sale in Viet Nam in the past six years and to explore any differences in the violation situations before and after the Law on Tobacco Control came into effect on 1st May 2013. Quantitative data were collected through observation of violations of the bans on tobacco advertising and promotion at points of sale in 10 provinces throughout Viet Nam in four survey rounds (2009, 2010, 2011, and 2015). Variation in violation prevalence over time was examined by chi-square test using a Bonferini method. Binary logistic regression was employed to identify the factors that may have influences on different types of violation. A level of significance of p<0.05 was used for all tests in this article. The most common form of violation was the display of more than one pack/one carton of a cigarette brand. Violation of bans on tobacco advertising increased while violations on promotion ban and on displaying tobacco decreased through time. Some factors associated with the tobacco advertising and promotion bans included surveyed years, types of points of sale, regions and areas where the points of sale were located. The enforcement of the bans did not improve even after the issuance and the enactment of the Law on Tobacco Control. This suggests that the monitoring and enforcement of bans on tobacco advertising and promotion at points of sale should be strengthened. Penalties should be strictly applied for violators as indicated in the current tobacco control legislation.
Journal of Mechanics Engineering and Automation, 2016
The application of cutting fluids in machining brings out many benefits, but their use is accompa... more The application of cutting fluids in machining brings out many benefits, but their use is accompanied by health and enviroment hazards. MQL (Minimum Quantity Lubricant) has become a preciously alternative solution for lubrication against dry machinning and flood cooling lubricant, and this is a step toward green machining. This paper presents a comprehensively experiemental study on investigation of MQL performance in hard milling of S60C steel for multiple responses, including surface quality, cutting forces and tool wear. Compared to dry milling, even-enhanced surfaces finish quality, 20% less cutting force (F t) and almost 112% prolonged tool lifetime are achieved by using MQL with 5% Emulsion in hard milling. In addition, this study compared the performances of MQL milling by using 5% Emulsion to the peanut oil completely harmless to the enviroment. This encouraging result, therefore, reveals that the MQL-employed hard milling can enable significant improvement in productivity, product quality, and overall machining economy even after covering the additional cost of designing and implementing MQL system. Moreover, this study also shows the limitation of peanut oils employed in MQL and proposes the further research in novel additives to enhance the performance of cooling lubricant for vegetable oils.
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