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Can Gio (CG), a mangrove forest with a dense network of tidal creeks, gradually grew and spread seaward on a coastal platform, which was built since about 8 ka before present (BP). Along with this development, a sand ridge began to form and moved back with the shoreline withdrawal landward in the Late Holocene. This mangrove environment is likely abandoned from the mainland but was, however, the place for settlement of ancient Vietnamese a few centuries BC. The CG mangrove forest was severely destroyed during the American War and was restored since 1980. However, the historical change of the landscape along the Saigon-Dong Nai River (SG-DNR) since the Late Holocene is not completely unraveled. By analyzing sediment cores with a multiproxy approach, we investigated the recent geological development with regard to the variation of the intensity of the East Asian palaeomonsoon and regarding the accommodation space, as both regulate the development of this coastal environment. A recently significant shift in the coastline, mainly due to a change of hydroclimatic factors, was observed. A continuous coastline retreat occurred over the last millennium, changing the depositional environment and reshaping the CG mangrove landscape. Along the present coast and tidal channels, partially strong erosion and bank failures occur, alternating with accretion at other coastal sections. This development tends to increase progressively.

Over the last four decades, banking crises around the globe have become longer. This, along with the unprecedented government responses to the Great Recession of 2007/08, has led to a critical question of whether political decisions were somehow to blame for these more prolonged crises. Despite growing concerns, little attention has been given to the political and institutional determinants of financial crisis duration. Using an extensive database with 125 countries observed over the period 1976-2017 and employing a discrete-time duration model, we find that the electoral cycle, political ideology, majority governments, and institutional quality matter for the understanding of the length of financial crises. This study also shows that, to better understand the dynamics of the duration of financial crises, it is essential to look at the duration dynamics in each type of financial crisis. Finally, allowing for more flexible duration dependence patterns, we observe that the duration of banking and twin/triple crises presents a non-monotonic cubic behavior, while the probability of debt crisis ending decreases monotonically over time.

A crucial material comprising a pneumatic tire is rubber. In general, the tire, or more specifically, the hysteresis effects brought on by the deformation of the part made of rubber during the procedure, heat up the part. In addition, the tire temperature depends on several factors, including the inflation pressure, automobile loading, car speed, road tire, the environmental conditions, and the tire geometry. This work focuses on using simulations to calculate the temperature and generated heat flow distributions of a rolling tire with constant velocity using the finite element method. For the sake of simplicity, it is assumed that the only components of the tire are rubber, body-ply, bead wire, and the rim. While the other components are believed to be made of a linear elastic material, the nonlinear mechanical behavior of the rubber is characterized by a Mooney–Rivlin model. Investigations are conducted into the combined effects of vehicle loads and inflation pressure. Hysteresis energy loss is used as a bridge to link the strain energy density to the heat source in rolling tires, and their temperature and heat flow distributions may be determined by steady-state thermal analysis. Thanks to the state-of-the-art computing method, the time required for connected 3D dynamic rolling tire simulations is reduced. The simulation outcomes demonstrate that the maximum temperature in this paper is attained with high weights, high velocities, and low inner inflated pressures. Overall, the maximum temperature is increased with the rise of all three variables. Moreover, the rise of the friction coefficient between the tread and road surface moves the high-temperature area towards the tread/sidewall connection area.

The research aimed to study 24 rock slope surfaces along the road around Hon Lon Island, Kien Hai district, Kien Giang province, Vietnam. The analytical results have determined slope failure, wedge failure, and toppling, which occurred on almost slope surface and the average percentage of plane failure is the largest. The average percent of plane failure is 19.23%, the wedge failure is 15.35%, and the toppling fault is 6.73%. Besides, the analytical results have also identified the slope surfaces which can be the key blocks: ND-13, 18, 23, 25, 34, 37, 45, 51, 62, 63. The other analytical results show that the existence of key blocks at the rock slope surfaces in the N-S direction, dip to E at the survey locations: ND-13, 23, 63 and dip to W at the survey locations: ND-37, 45; in the NE-SW direction, dip to SE at the survey locations: ND-15, 62 and dip to NW at the survey locations: ND-18, 34; in the NW-SE direction, dip to SW at the survey location ND-51. These results have important significance to support for protecting slope surface safety.

Introduction: Many methods have been proposed to handle the image restoration problem with Poisson noise. A popular approach to Poissonian image reconstruction is the one based on Total Variation. This method can provide significantly sharp edges and visually fine images, but it results in piecewise-constant regions in the resulting images. Purpose: Developing an adaptive total variation-based model for the reconstruction of images contaminated by Poisson noise, and an algorithm for solving the optimization problem. Results: We proposed an effective way to restore images degraded by Poisson noise. Using the Bayesian framework, we proposed an adaptive model based on a combination of first-order total variation and fractional order total variation. The first-order total variation model is efficient for suppressing the noise and preserving the keen edges simultaneously. However, the first-order total variation method usually causes artifact problems in the obtained results. To avoid this drawback, we can use high-order total variation models, one of which is the fractional-order total variation-based model for image restoration. In the fractional-order total variation model, the derivatives have an order greater than or equal to one. It leads to the convenience of computation with a compact discrete form. However, methods based on the fractional-order total variation may cause image blurring. Thus, the proposed model incorporates the advantages of two total variation regularization models, having a significant effect on the edge-preserving image restoration. In order to solve the considered optimization problem, the Split Bregman method is used. Experimental results are provided, demonstrating the effectiveness of the proposed method. Practical relevance: The proposed method allows you to restore Poissonian images preserving their edges. The presented numerical simulation demonstrates the competitive performance of the model proposed for image reconstruction. Discussion: From the experimental results, we can see that the proposed algorithm is effective in suppressing noise and preserving the image edges. However, the weighted parameters in the proposed model were not automatically selected at each iteration of the proposed algorithm. This requires additional research.

A choice experiment (CE) with approximately 1000 respondents was designed and conducted to estimate economic benefits associated with air quality improvements in Hanoi City, the capital of Vietnam. In this CE application, different scenarios of air quality improvements were described based on reduction in morbidity and mortality risk, and increase in urban tree cover to elicit respondents’ willingness-to-pay (WTP). To gain better understanding of the WTP estimates, the econometric analysis applied several models, including conditional logit models, a mixed logit model, a generalized multinomial logit model and a latent class model. The WTP for maximal improvements is about 0.16–1.88% of household income. Results of marginal WTP for reduction in morbidity and mortality risk suggest that the values of statistical illness relating to air pollution range from USD1,120 to USD8,280, and the values of statistical life fall between USD7,100 and 64,700. Based on marginal WTP for boosting urban tree cover, aggregate WTP estimated for Hanoi population is about USD18.6–124 million per year to achieve the tree cover level of 18m2 per capita. Given the budget limitation, the information on residents’ WTP for improving air quality would be useful for policy makers to invest efficiently in controlling air pollution.

PurposeThis purpose of this paper is to understand residents’ choice of preferred measures and their willingness-to-pay (WTP) for the measures to improve the air quality of Hanoi city.Design/methodology/approachQuestionnaire surveys were conducted to collect the opinions of 212 household representatives living in Hanoi City. The survey tools were tested and adjusted through an online survey with 191 responses. Multivariate probit and linear regression models were used to identify determinants of respondents’ choices of measures and their WTP.FindingsRespondents expressed their strong preferences for three measures for air quality improvements, including: (1) increase of green spaces; (2) use of less polluting fuels; (3) expansion of public transportation. The mean WTP for the implementation of those measures was estimated at about 148,000–282,000 Vietnamese dong, equivalent to 0.09–0.16% of household income. The respondents’ choices appear to be consistent with their characteristics and needs, such as financial affordability, time on roads and their perceived impacts of air pollution. The WTP estimates increase with perception of air pollution impacts, time on roads, education and income; but are lower for older people.Practical implicationIncrease of green spaces can be the measure to which policy makers should pay more attention. The match-up of residents needs and well-informed plans will be an important key to success.Originality/valueThis appears to be the first attempt to test the validity of public opinions on choices of measures for improving urban air quality in Vietnam. Our WTP estimates also contribute to the database on the values of improved air quality in the developing world.

The solution of using a collector well was investigated to take additional water, overcome the weaknesses of the conventional weir that are prone to sediment accumulation intake structures of a weir, especially at the location where weir is not needed. The solution was considered using a laboratory model at Hydraulic Construction Institute - Vietnam Academy for Water Resources. The results of model research and construction of a pilot project in Muong Lan commune, Muong Ang district, Dien Bien province show that collector well can collect water over 31 l/s ensuring water supply for more than 20 ha of rice field.

This study explores ordering effects in close association with strategic behaviour in a discrete choice experiment surveying preference for improvements in cyclone warning services. To examine strategic behaviour, we assign respondents to assumed non-strategic and strategic groups using their answers to two questions on their beliefs about the consequentiality of the survey and the payment obligation. The data from each group are analysed non-parametrically and parametrically to investigate ordering effects in their preferences. Comparison of results between the two groups suggests that preferences of possibly strategic respondents are relatively unstable over a sequence of six choice tasks. It appears that these respondents could have behaved strategically from the fourth task onwards, diverting their responses from the choices of the non-strategic respondents. This finding may indicate that strategic behaviour is a possible cause of position-dependent ordering effects in the repeated question format.

The production of natural astaxanthin is usually accomplished by suspended cultivation of the microalgae Haematococcus pluvialis. In this study, for the purpose of cost reduction, H. pluvialis is grown in pilot scale angled twin-layer porous substrate photobioreactors with light energy from red/blue LEDs that can produce red light, blue light, or a combination of blue-red light. The total dry biomass of the microalgae reached a maximum of 40.74 g.m-2under blue-red LEDs. The early initiation of blue-red LED illumination (on day 2) after algae immobilization in the biofilm resulted in the highest accumulation of astaxanthin in the dry biomass, which reached a maximum of 1.3% (w/w) after 10 d of culture.

An angled twin-layer porous substrate photobioreactor (TL-PSBR) using LED light was designed to cultivate Nannochloropsis oculata. Flocculation and sedimentation by modification of pH to 11 were determined as the optimal method for harvesting the N. oculata inoculum. The following optimised parameters were found: tilt angle 15°, Kraft 220 g m

Introduction: A common problem in image restoration is image denoising. Among many noise models, the mixed Poisson-Gaussian model has recently aroused considerable interest. Purpose: Development of a model for denoising images corrupted by mixed Poisson-Gaussian noise, along with an algorithm for solving the resulting minimization problem. Results: We proposed a new total variation model for restoring an image with mixed Poisson-Gaussian noise, based on second-order total generalized variation. In order to solve this problem, an efficient alternating minimization algorithm is used. To illustrate its comparison with related methods, experimental results are presented, demonstrating the high efficiency of the proposed approach. Practical relevance: The proposed model allows you to remove mixed Poisson-Gaussian noise in digital images, preserving the edges. The presented numerical results demonstrate the competitive features of the proposed model.

This study aims to find the optimized parameters for surveying the milling process of S50C steel in a minimum quantity lubrication (MQL) environment using a support vector machine-genetic algorithm (SVM-GA). Based on the experimental matrix designed by the Taguchi method, surface roughness and cutting force data were collected corresponding to each experiment with changes in input parameters such as cutting speed, tooth feed rate, and axial depth of cut, along with changes in two parameters of the minimum lubrication system: flow rates and injection pressure. Through analysis by the SVR-NSGAII method, the study obtained the optimal parameters of cutting and lubricating conditions when prioritizing either surface roughness or focusing on the cutting force; however, the most comprehensive result is believed to be achieved by balancing these two factors. So, when striving for the neutral value of both output parameters, which are surface roughness (µm) and cutting force (N), the optimum parameters including injection pressure (MPa), flow rates (mL/h), cutting speed (m/min), feed rate (mm/tooth), and axial depth of cut (mm) are proposed.

In this study, samples from 429 dog individuals across three main regions of Vietnam (Southern Vietnam (SVN), Central Vietnam (CVN), and Northern Vietnam (NVN)) were collected to analyze the 582 bp region mtDNA HVI, so as to study the genetic diversity and to screen the rare haplotype E in the Vietnamese village dog population. Nine new haplotypes A, two new haplotypes B, and three haplotypes C were unique to Vietnam dogs, in which the new haplotypes An3, An7, Cn1, and Cn3 concerned mutations at new polymorphism sites (15,517, 15,505, 15,479, and 15,933, respectively) which have not been previously reported. The detection of haplotypes A9 and A29, and the appearance of haplotype A200 in the two individual dogs sampled support that the Southeast Asian dog is the ancestor of today’s Australian dingo and Polynesian dog. The two rare haplotypes E (E1 and E4) were reconfirmed in Vietnamese dogs and discussed. This study also contributes to strengthening the theory of domestication of dogs to the south of the Yangtze River and the Southeast Asian origin of the dingo.

This study presents a novel approach named as “multiple objective social group optimization” (MOSGO) to tradeoff time, cost, quality, and carbon dioxide emission (TCQC) factors in generalized construction projects. The proposed algorithm modifies the operation mechanism to balance the exploration and exploitation abilities of the optimization process. The TCQC tradeoff problem considers all types of logical relationships between project activities. Two practical case studies demonstrate the ability of MOSGO-generated, non-dominated solutions. In addition, evidential reasoning is applied to select a compromise solution for project implementation. Comparisons between the MOSGO and four well-known algorithms (MODE, MOABC, MOPSO, and NSGA-II) to verify the efficiency and effectiveness of the developed algorithm. According to the statistical analysis, the proposed algorithm generated the highest values of diversification measurement (DM) of 26.113 and 40.27; the highest values of hyper-volume (HV) of 0.875 and 0.881 in case 1 and case 2, respectively. The proposed algorithm also found solutions with lowest mean ideal distance (MID) and spread (SP) values of 0.872 and 0.462 in the first case and of 0.754 and 0.689 in the second case. MOSGO showed had better diversify and convergence, gained wider spread, and yielded higher uniformity of solutions than the compared multiple objective evolutionary algorithms.

This paper assesses the role of the political environment in the timing of financial crises over a sample of 85 countries during the period 1975-2017. We consider systemic banking, currency, and sovereign debt crises in addition to twin and triple crises. Using a fixed effects logit model, this study shows that banking and currency crises are more likely to occur within one year after elections. There is also evidence that the probability of currency crises increases when right-wing parties are in office. Moreover, time in office of incumbent chief executives reduces the likelihood of any type of financial crises. The incidence of twin and triple crises is lower when majority governments are in office. This study contributes to the literature by calling attention to the importance of some political factors for different types of financial crises.

This study investigates the impacts of the United States (US) federal funds rate and Chinese interbank rate on the behaviors of stablecoins and traditional cryptocurrencies. We employ GARCH, EGARCH and Fixed Effects models for the daily sample of the top five stablecoins and the top five traditional cryptocurrencies in terms of market capitalization from December 2018 to December 2019. Our results show that a higher federal funds rate and Chinese interbank rate compress the prices and price volatility of stablecoins. In contrast, higher rates from both countries increase the prices and price volatility of traditional cryptocurrencies. Both rates also increase the trading value of both types of coins. The federal funds rate tends to have stronger impacts compared to the Chinese interbank rate on both types of coins, except for the price response of traditional cryptocurrencies.

Inappropriate use of antibiotics in animal production system is one of the major factors leading to the antibiotic resistance (ABR) development. In Vietnam, the ABR situation is crucial as antibiotics have been used indiscriminately for disease prevention and as growth promoters in animals. Thus, a thorough understanding on the ABR in veterinary settings would be beneficial to the Vietnam public health authority in formulating timely interventions. This review aimed to provide information on the current status of antibiotic usage in animal husbandry in Vietnam, identified gaps in research, and suggested possible solutions to tackle ABR. To this end, data on ABR in animals were extracted from 3 major electronic databases (PubMed, Web of Science, and ScienceDirect) in the period of January 2013-December 2020. The review findings were reported according to PRISMA, which highlighted the emergence and persistence of ABR in bacterial isolates, including Escherichia coli, Enterococcus spp., and Salmonella species, obtained from pigs and poultry. The lack of awareness of Vietnamese farmers on the antibiotic utilization guidelines was one of the main causes driving the animal ABR. Hence, this paper calls for interventions to restrict antibiotics use in food-producing animals by national action plan and antibiotics control programs. Additionally, studies to evaluate knowledge, attitude, and practice (KAP) of the community are required to promote rational use of antibiotics in all sectors.

The study analysed the dose–response relationship between dietary viscosity and nutrient digestibility, faecal waste characteristics in striped catfish and the long-term impacts of viscosity on performance of striped catfish. This was done in two experiments: Exp.1 lasted 29 days, in which six dietary viscosity levels were created by including different amount of guar gum (GG; 0, 0.25, 0.5, 1.0, 2.0 or 3.0 g/kg) and Exp.2 lasted 60 days and assessed the long-term effects of three dietary GG levels (0, 0.5 and 3.0 g/kg) were checked. In Exp.1, digestibility of nutrients (except crude fat) decreased linearly with dietary viscosity. With increasing viscosity, removal efficiency of faeces from the water reduced linearly, whereas the total amount of faeces produced and the fraction of big-sized faecal particles (>2 mm). increased linearly. In Exp.1, viscosity did not affect performance. However, in Exp.2, the GG inclusion level of 3.0 g/kg (1.72 cP for the viscosity) affected fish performance. In conclusion, the best strategy for faecal waste management in striped catfish by dietary viscosity is to keep it as low as possible in the diet.

The bus frame structure is mainly subject to the complex loads that affect the vehicle during operation, so the design of frame structure is always a key issue in the design, consuming a lot of time and effort. To enhance the flexibility of the design and calculation process, minimize the changes in design of the same type of bus, enhance the level of standardization and mass production of the product, the using of 3D parametric software to carry out designing the bus frame structure has become an indispensable trend in the development of automotive manufacturing technology. This article presents the results of research on the features of the geometric model establishment of Solidworks software as well as the interactive ability, data access between Solidworks and Excel software. Based on the features of the software and on the basis of the analysis of the design process, the structural features of the bus frame, the method of rapid shaping is set up. The application of rapid shaping by using Solidworks and Excel software to increase productivity, reduce time, effort and budget for frame structure design process of bus.

The model predicting Bitcoin price formation remains a mystery to academia and investors. Newly invented cryptocurrencies (alternative coins – altcoins) with enhanced features may become close substitutes to Bitcoin in terms of risk diversification. Employing Autoregressive-Distributed-Lag (ARDL) estimations, we document the evidence that the introduction of a new altcoin tends to lower Bitcoin return by 0.7% which is substantial given that the average and median daily returns of Bitcoin are 0.63% and 0.27%, respectively. Our study suggests that the negative impact of an Initial Public Offering on existing stock prices can also be observed in the cryptocurrency market: altcoin introductions reduce Bitcoin return.

In recently years, Automotive industry in Vietnam is a fast growing sector, mainly reliant on domestic produces, assembly and sales. There are some details of cars that have been modeled, calculated to research and fabricate. Body vibration of the vehicles is one of the criteria to evaluate quality in the process of manufacturing and assembling automobiles. There are so many factors affecting on vibration of vehicles, in that body structure is one of the main causes. Up to now, automobiles manufactured and assembled in Vietnam have not yet had specific evaluations and standards on vibration. Determination of characteristic body vibration is a main part to reduce sound and vibration. In this paper, the modelling and calculating the body’s characteristic vibration of cars manufactured, assembled in Vietnam was researched. The body structure is designed by 3D model using commercial Catia Software. The model was transformed from Catia software to Hypermesh software, using finite element method to simulate. The calculation results of 25 measurement characteristic vibrations whose frequency is in range of 22.77 Hz to 97.21 Hz. The results are shown that, characteristic vibration of state 1 and 2 significantly influence the noise of the body. This is also the basis for optimal analysis of the body structure to control the vibration and noise of automobiles.