Coastal morphodynamical modelling in nonlinear shallow water framework using a coordinate transformation method

A 1D numerical model of Nonlinear Shallow Water Equations (NSWEs) coupled to an advection equation for suspended sediment and a bed evolution equation is developed. The moving boundary at the shoreline is treated by a coordinate transformation method (CTM). An absorbing-generating seaward boundary condition in the transformed variables is also developed. The purely hydrodynamic component (NSWEs) is verifed against analytical results. The NSWEs plus advection equation is verifed quasi-analytical results. The fully-coupled model with bed change due to bed-load is verifed against a single swash event and long-term numerical simulation. Excellent agreement is observed in all verifcations

Outage performance analysis of non-orthogonal multiple access with time-switching energy harvesting

In recent years, although non-orthogonal multiple access (NOMA) has shown its potentials thanks to its ability to enhance the performance of future wireless communication networks, a number of issues emerge related to the improvement of NOMA systems. In this work, we consider a half-duplex (HD) relaying cooperative NOMA network using decode-and-forward (DF) transmission mode with energy harvesting (Ell) capacity, where we assume the NOMA destination (D) is able to receive two data symbols in two continuous time slots which leads to the higher transmission rate than traditional relaying networks. To analyse EH, we deploy time-switching (TS) architecture to comprehensively study the optimal transmission time and outage performance at D. In particular, we are going to obtain closed-form expressions for outage probability (OP) with optimal TS ratio for both data symbols with both exact and approximate forms. The given simulation results show that the placement of the relay (R) plays an important role in the system performance.Web of Science253918

1D morphodynamical modelling of macro-tidal sandy beaches under pure tidal currents

This research aims to study bed level evolution of a sandy beach under tidal effects over a long-time scale, using a fully-coupled hydro-morphodynamical numerical model. The proposed model originates from a system comprising nonlinear shallow water equations (NSWEs), an advection equation to describe suspended load and the Exner equation for bed change. Here non-flux conservative NSWEs are used, since no shock waves are formed by tidal motion. The moving boundary at the shoreline is treated by a coordinate transformation method (CTM) which can capture accurately the time variation of the shoreline. The absorbing-generating seaward boundary allows description of the outgoing hydrodynamic signals along with incoming signals. We also include the seaward boundary condition proposed by Incelli et al. [2015] to allow sediment to exit and enter the domain whilst maintaining the conservation. A fully coupled model with both bed-load and suspended-load transport is developed. The model performance is verified in both hydrodynamics and morphodynamics against available analytical and numerical solutions. The morphodynamic evolution of a sandy beach under macro-tidal currents over a duration of 100 tidal cycles is investigated. We consider both bed load and suspended load transport, either in individual or combined mode. Furthermore, we also consider how the coupling could affect bed change by considering the fully coupled against the quasi coupled one. Regarding suspended load only, erosion is observed offshore; while deposition always occurs at the intertidal zone. The non zero bed change under symmetrical tide due to settling lag effect, which is the difference in phase between the suspended sediment concentration and velocity. Bed change due to suspended load depends not only on the exchange parameter but also on the bed mobility parameter. While bed mobility parameter mainly affects the bed change rate, the exchange parameter affects both bed change rate and patterns. Particularly, in case of low exchange parameter value, erosion is also observed in the sub-tidal region. Bed change due solely to bed load is only significant in the intertidal region. This is partly due to the shock condition applied in the shoreline boundary. Moreover, the shoreline velocity due to transient from initial still water is much higher than normal, resulting in higher bed change after the first cycle compared to the remaining simulation time. Although the hydrodynamic nonlinearity is small in tidal motion, it still exists and is higher in the intertidal region than further offshore. As a result, the spatial derivatives of bed load flux is not zero and is higher in the intertidal region. Bed change under suspended load transport is more dominant than under bed load transport. Moreover, bed change under bed load converges after a shorter time than that due to suspended load. The results of fully-coupled and quasi-coupled models qualitatively agree in bed change magnitude and pattern. The difference is proportional to bed change. In particular, the higher the bed change rate is, the greater the difference between the two model is. The quasi-coupled model obtains total suspended load or bed load over a tide. Then bed change is only updated after every tide. The comparison results have shown that in cases of high bed mobility or low exchange parameter, the coupling effect is significant

SEROTYPES, TOXINS AND ANTIBIOTIC RESISTANCE OF Escherichia coli (E.COLI) STRAINS ISOLATED FROM DIARRHEIC RABBITS IN PHU VANG, THUA THIEN HUE

This study was conducted to determine the prevalence of E. coli in rabbits, their biochemical and serological characteristics, common virulence genes, and antibiotic resistance. The diarrhea rabbit feces were collected from households and rabbit farms in Phu Vang - Thua Thien Hue with a total of 250 samples for testing. The results showed that rabbits age from 31 to 45 days old had the highest incidence of diarrhea disease caused by E.coli (92.0%) and the lowest infection rate was observed in rabbits over 60 days old with an infection rate of 30%. Further, the isolated E.coli strains tested biochemical characteristics showed 100% motile, positive for indole and methyl red, fermenting glucose and lactose. Simultaneously these strains were detected belong to 7 serotypes O103, O157, O158, O169, O44, O125, O153 and susceptible to cefuroxime (95.45%), akamicin (86.37%), streptomycin (81.82%), amoxicillin (81.82%), tetracycline (68.18%), colistin (68.18%), ampicillin (63.63%), gentamycin (59.10%) and levofloxacin (50.0%), whilst resistant to doxycycline (100%), sulfamethoxazole-bactrim (95.46%), and neomycin (86.37%). By using PCR assay for detection of virulence genes of the isolated E. coli strains, there were 7 strains carried virulence genes, of which 4/7 E. coli strains carried eaeA and tsh genes (57.14%), 2/7 strains carried stx2 gene (28.57%); 1/7 E. coli strains carried stx1 gene (14.28%) and the F4, F5 and F6 genes were not found in all serotypes in this study

Outage and bit error probability analysis in energy harvesting wireless cooperative networks

This study focuses on a wireless powered cooperative communication network (WPCCN), which includes a hybrid access point (HAP), a source and a relay. The considered source and relay are installed without embedded energy supply (EES), thus are dependent on energy harvested from signals from the HAP to power their cooperative information transmission (IT). Taking inspiration from this, the author group investigates into a harvest-then-cooperate (HTC) protocol, whereas the source and the relay first harvest the energy from the AP in a downlink (DL) and then collaboratively work in uplink (UL) for IT of the source. For careful evaluation of the system performance, derivations of the approximate closed-form expression of the outage probability (OP) and an average bit error probability ( ABER) for the HTC protocol over Rayleigh fading channels are done. Lastly, the author group performs Monte-Carlo simulations to reassure the numerical results they obtained.Web of Science255746

Outage performance analysis and SWIPT optimization in energy-harvesting wireless sensor network deploying NOMA

Thanks to the benefits of non-orthogonal multiple access (NOMA) in wireless communications, we evaluate a wireless sensor network deploying NOMA (WSN-NOMA), where the destination can receive two data symbols in a whole transmission process with two time slots. In this work, two relaying protocols, so-called time-switching-based relaying WSN-NOMA (TSR WSN-NOMA) and power-splitting-based relaying WSN-NOMA (PSR WSN-NOMA) are deployed to study energy-harvesting (EH). Regarding the system performance analysis, we obtain the closed-form expressions for the exact and approximate outage probability (OP) in both protocols, and the delay-limited throughput is also evaluated. We then compare the two protocols theoretically, and two optimization problems are formulated to reduce the impact of OP and optimize the data rate. Our numerical and simulation results are provided to prove the theoretical and analytical analysis. Thanks to these results, a great performance gain can be achieved for both TSR WSN-NOMA and PSR WSN-NOMA if optimal values of TS and PS ratios are found. In addition, the optimized TSR WSN-NOMA outperforms that of PSR WSN-NOMA in terms of OP.Web of Science193art. no. 61

Kinetic modeling of essential oil hydro-distillation from peels of pomelo (Citrus grandis L.) fruit grown in Southern Vietnam

Thorough understanding of kinetics plays a key role in improving existing industrial processes. In this study, we attempted to model the kinetics of the hydro-distillation process that produces essential oil from peels of pomelo (Citrus grandis L.) fruit, which is a product with high economic value and a wide range of applications. We first determined the optimal water-to-material ratio for attaining maximal oil yield. Then, further experimental attempts were carried out at different distillation rates to generate experimental data to fit three kinetic models, namely first-order kinetics model, instantaneous washing, followed by diffusion model and simultaneous washing and diffusion model. Overall, the three models have well described the experimental kinetic data on hydro-distillation (R2> 90%). Of which, the simultaneous washing and diffusion model attaining the R2 of 99.97% was chosen as the most suitable to describe the kinetics of the extraction process. Estimated parameters also shown that the washing stage occurs more rapidly than the later, diffusion stage. GC-MS results showed that the obtained oil sample was characterized by the dominance of the D-Limonene compound (97.873%)

AN INVESTIGATION INTO THE COMMON ERRORS OF WORD FORM USED IN WRITING OF THE FRESHMEN: A CASE STUDY

English has been used all across the world, including in Vietnam. From middle school to high school and even university, Vietnamese students have numerous opportunities to engage with English grammar, but there is still a significant gap between their understanding and the correct application of English grammar. In fact, Grammar has a significant impact on the writing skills of Vietnamese students in general, and especially the first-year students of English majors who were not much exposed to writing in high school, so they are not yet used to writing at a higher level. The majority of errors in their writings are due to the influence of their mother tongue and a lack of frequent practice and their misuse of word forms, as a matter of fact, the expected results have not been satisfactory. Based on the general insight into the writing competence of the freshmen, the study titled “An investigation into the common errors of word forms made in the writings of the freshmen: A case study” was done with the English-major students. A close survey was deliberately done with 142 paragraphs written by the first-year students to investigate the common errors of word forms made in their writings. From what was collected, the study subsequently offered some suggestions for helping the students improve their writing skills.  Article visualizations

Multiple Wolbachia strains provide comparative levels of protection against dengue virus infection in Aedes aegypti.

The insect bacterium Wolbachia pipientis is being introgressed into Aedes aegypti populations as an intervention against the transmission of medically important arboviruses. Here we compare Ae. aegypti mosquitoes infected with wMelCS or wAlbB to the widely used wMel Wolbachia strain on an Australian nuclear genetic background for their susceptibility to infection by dengue virus (DENV) genotypes spanning all four serotypes. All Wolbachia-infected mosquitoes were more resistant to intrathoracic DENV challenge than their wildtype counterparts. Blocking of DENV replication was greatest by wMelCS. Conversely, wAlbB-infected mosquitoes were more susceptible to whole body infection than wMel and wMelCS. We extended these findings via mosquito oral feeding experiments, using viremic blood from 36 acute, hospitalised dengue cases in Vietnam, additionally including wMel and wildtype mosquitoes on a Vietnamese nuclear genetic background. As above, wAlbB was less effective at blocking DENV replication in the abdomen compared to wMel and wMelCS. The transmission potential of all Wolbachia-infected mosquito lines (measured by the presence/absence of infectious DENV in mosquito saliva) after 14 days, was significantly reduced compared to their wildtype counterparts, and lowest for wMelCS and wAlbB. These data support the use of wAlbB and wMelCS strains for introgression field trials and the biocontrol of DENV transmission. Furthermore, despite observing significant differences in transmission potential between wildtype mosquitoes from Australia and Vietnam, no difference was observed between wMel-infected mosquitoes from each background suggesting that Wolbachia may override any underlying variation in DENV transmission potential

Assessing status and habitat of siamese fireback (Lophura diardi) by using camera trap in Lo Go-Xa Mat National Park, Vietnam

Siamese fireback, Lophura diardi, belonging to Galliformes is at risk due to habitat loss and hunting, which are main challenges to conservation of the species. In order to provide scientific information to conserve the L. diardi, we implemented a camera-trap survey in Lo Go-Xa Mat National Park from 2017 to 2018. Occupancy and Poisson regression models were used to investigate presence of the species and potential factors influencing the occurrence of the species in the study area. Our results showed that the probability of occurrence of the species at locations within the park was high at 0.84 (0.69–0.92) and detection probability was relative low at 0.19 (0.16–0.23). The best models consistently suggested that the abundance of the species was high in closed canopy forest cover (β = 0.41), but appeared to be notably lower in areas far away from the ranger stations (β = -0.25) and in places with high frequency of human (β = -0.22). This research provided the first quantitative information of status and potential factors influencing occurrence of the L. diardi in the park, which is an essential data for developing practical actions to protect the species and monitoring program in the future for the park.