Drillships and semi-submersible platforms (SSPs) are used for oil and gas offshore exploration and production activities in seas deeper than 300 meters. These SSPs must be maintained in a predefined ...position at a predetermined location to complete their offshore tasks. They must have a way to generate forces and angular momentum to balance out external factors (wind, currents, and waves). Actually, the offshore support vessel (OSV) is assisted by dynamic positioning systems (DPSs) in all of its operations, including transit, survival, and station maintenance, and there are significant differences in propulsion systems. In this paper, we suggested a path planning robust adaptive fuzzy-free fault-tolerant control (RAFFFTC) for SSPs with actuator constraints to improve the robust performance and quality of the control system. Accordingly, the adaptive fuzzy controller with adaptive law has been created to change the membership function of the fuzzy controller, and the Lyapunov theory for system stability analysis has been used to illustrate the <inline-formula> <tex-math notation="LaTeX">H_\infty</tex-math> </inline-formula> performance of robust tracking, reduced errors in the path planning control of the SSP in the cases of thrusters and disturbance-free fault-tolerant. Finally, a simulation experiment with two scenarios compared its performance to the other controller, with results verifying the proposed controller's effectiveness and demonstrating that it achieved the control quality required in the SSP control process.
This paper aims to develop a genetic algorithm to adjust an fuzzy controller for Vessels' Dynamic Positioning System (Vessels' DPs). It is well-known that nonlinearities affecting the control ...accuracy of the DPs are related to the arrangement of different types of thrusters in the vessels, such as azimuth thrusters (electric, L-drive, and Z-drive), bow thrusters, stern thrusters, water jets, and propulsion propellers with rudders. Compared with the traditional fuzzy control methods, the proposed Robust Adaptive Fuzzy Control using Genetic Algorithm (RAFC-GA) not only overcomes the influence of nonlinearities in the DPs, but also eliminates the impact of parameter uncertainties. Therefore, the tracking performance is excellent and robustness is maintained. The RAFC-GA control method is superior to the conventional fuzzy control methods in the two following aspects: 1) to find the optimal values for the fuzzy structure parameters to satisfy the robust condition under the effect of disturbances and nonlinearities in the DPs without weakening the output tracking performance and robustness, 2) to improve the quality of the system by optimizing values for the fuzzy structure using genetic algorithm which dynamically adjusted the coverage domain width and the overlap degree of membership functions. Simulation results of the RAFC-GA are evaluated in comparison with other methods. The RAFC-GA performs the desired transient response of DPs better than others in three case studies, which proves the effectiveness of the proposed solution.
In-line with the World Health Organization's (WHO) Global Technical Strategy for Malaria (2016-2030), Vietnam is striving to eliminate malaria by 2030. Targeting appropriate interventions in ...high-risk populations such as forest and forest-fringe communities is a critical component of malaria elimination efforts in Vietnam. In 2016, a household-level malaria indicator survey was conducted in Phu Yen Province, Vietnam with the aim of assessing the knowledge, behaviors and associated risks of malaria infection among priority mobile and migrant populations (MMPs) working and sleeping in forests and on farms. A total of 4211 people were included in the survey, comprised of 1074 heads of households and 3137 associated household members. Of the 1074 head-of-household respondents, 472 slept in a forest, 92 slept on a farm, 132 slept in both forests and farms, and 378 slept at their villages within the last 12 months. Age, literacy, and occupation were significantly different among those who slept in a forest versus on a farm. Of 301 respondents who answered questions about malaria risk factors at sleeping sites, 35% were somewhat aware of malaria prevention practices, but only 4% could recall at least four malaria prevention messages. Among the same group of 301 respondents, only 29% used nets and only 11% used treated nets. Ownership and use of nets among forest-goers was significantly lower than those who slept on a farm or in their village. Huts without walls were significantly prominent forest sleeping site locations (POR = 10.3; 95% CI 4.67-22.7). All respondents who slept in a forest requested standby malaria drugs and one-third of them self-treated without blood testing. Results from this study highlight the importance of capturing relevant location-specific data among priority populations such as remote forest and farm going mobile and migrant populations in Vietnam. Data regarding behavioral practices, knowledge, preventative measures, and intervention coverage at remote-area transmission sites must be routinely captured to effectively monitor progress and refine targeted intervention strategies accordingly.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The vessel motion is a nonlinear and complicated in practical applications. The factors which affect vessel motion, mainly come from environmental influences. In this paper, we develop a fuzzy ...particle swarm optimization algorithm that applies to dynamic positioning system for stabilizing a vessel motion under unexpected impacts. The structure parameter of fuzzy system is calibrated by particle swarm optimization method. The coverage domain width and the overlap degree influence of membership function are adjusted dynamically from system errors. Thereby optimizing the control signal and enhancing the dynamic positioning system quality. Simulation studies with comparisons on a supply vessel are carried out. The proposed in a better response compared to other method such as fuzzy that proved effective of the proposed controller.
Abstract
Background
Malaria rapid diagnostic tests (RDTs) remain the main point-of-care tests for diagnosis of symptomatic
Plasmodium falciparum
malaria in endemic areas. However, parasites with gene ...deletions in the most common RDT target, histidine rich protein 2 (
pfhrp2
/HRP2), can produce false-negative RDT results leading to inadequate case management. The objective of this study was to determine the prevalence of
hrp2/3
deletions causing false-negative RDT results in Vietnam (Gia Lai and Dak Lak provinces).
Methods
Individuals presenting with malaria symptoms at health facilities were screened for
P. falciparum
infection using light microscopy and HRP2-RDT (SD Bioline Malaria Antigen Pf/Pv RDT, Abbott). Microscopically confirmed
P. falciparum
infections were analysed for parasite species by 18S rRNA qPCR, and
pfhrp2
and
pfhrp3
exon2 deletions were investigated by nested PCR.
pfhrp2
amplicons were sequenced by the Sanger method and HRP2 plasma levels were determined by enzyme-linked immunosorbent assay (ELISA).
Results
The prevalence of false-negative RDT results among symptomatic cases was 5.6% (15/270). No
pfhrp2
and
pfhrp3
deletions were identified. False-negative RDT results were associated with lower parasite density (p = 0.005) and lower HRP2 plasma concentrations (p < 0.001), as compared to positive RDT.
Conclusions
The absence of
hrp2/3
deletions detected in this survey suggests that HRP2-based malaria RDTs remain effective for the diagnosis of symptomatic
P. falciparum
malaria in Central Vietnam.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Oil and gas projects differ from regular investment projects in that they are frequently large-scale, categorised as vital national projects, highly technological, and associated with significant ...risks. Drilling rigs are a crucial component of the oil and gas sector and the majority of the systems and equipment aboard drilling rigs are operated automatically. Consequently, it is crucial to address the topic of an advanced control theory for off-shore systems. Network technology connected to control is progressively being used to replace outdated technologies, together with other contemporary technologies. In this study, we examine how to adapt a networked control jacking system to the effects of internal and external disturbances with a time delay, using a Fuzzy controller (FC)-based particle swarm optimisation. To demonstrate the benefit of the proposed approach, the developed Fuzzy Particle Swarm Optimisation (FPSO) controller is compared with the fuzzy controller. Finally, the results from simulations and experiments utilising Matlab software and embedded systems demonstrate the suitability of the proposed approach.
Seagrasses are among the most important ecosystems of continental and island coastal waters globally. Analyses of the species diversity, structure, and distribution mapping of seagrass communities ...provide a scientific basis for seagrass conservation and development and protection of the marine environment. The application of remote sensing, especially using very high-resolution remote sensing data, in mapping seagrass distribution confers high accuracy and detailed results. The distribution of seagrass communities and benthic biomes typical of Nam Yet Island, Truong Sa Archipelago, Vietnam was mapped using object-based classification of Pléiades satellite imagery with four spectral bands (red, blue, green, and near-infrared) and the Green–Blue Normalized Difference Vegetation Index, combined with handheld positioning devices (total field samples 100, overall accuracy 91%, kappa coefficient = 0.88). Besides, by sampling and measurement in the field, two seagrass species,
Thalassia hemprichii
and
Halophila ovalis
were identified with the same structure, density, and biomass in the northern and southern parts of the island. The application of high-resolution remote sensing images combined with field surveys contributes to improving the accuracy of seagrass distribution maps as well as benthic biome ones for shallow sea areas. Establishing a seagrass distribution map and assessing the diversity of seagrass is the basis for the conservation and development of the current seagrass community at Nam Yet Island.
The use of gnobiotic brine shrimp (Artemia spp.) for ecotoxicology and bacteria-host interaction studies is common. However, requirements for axenic culture and matrix effects of seawater media can ...be an obstacle. Thus, we investigated the hatching ability of Artemia cysts on a novel sterile Tryptic Soy Agar (TSA) medium. Herein, we demonstrate for the first time that Artemia cysts can hatch on a solid medium without liquid, which offers practical advantages. We further optimized the culture conditions for temperature and salinity and assessed this culture system for toxicity screening of silver nanoparticles (AgNPs) across multiple biological endpoints. Results revealed that maxima hatching (90%) of embryos occurred at 28 °C and without addition of sodium chloride. When capsulated cysts were cultured on TSA solid medium Artemia were negatively impacted by AgNPs at 30-50 mgL
in terms of the embryo hatching ratio (47-51%), umbrella- to nauplii-stage transformation ratio (54-57%), and a reduction in nauplii-stage growth (60-85% of normal body length). At 50-100 mgL
AgNPs and higher, evidence of damage to lysosomal storage was recorded. At 500 mgL
AgNPs, development of the eye was inhibited and locomotory behavior impeded. Our study reveals that this new hatching method has applications in ecotoxicology studies and provides an efficient means to control axenic requirements to produce gnotobiotic brine shrimp.
Mesoporous carbon (N-CMK3) decorated with different amounts of SnO
2
nanoparticles was prepared in a controllable manner by using an incipient wetness impregnation technique, followed by a chemical ...reduction process, for application as a supercapacitor. The results of the analysis demonstrated that the surface area and pore volume of N-CMK3 decorated with SnO
2
continued to decrease after impregnation with increasing amounts of SnO
2
. The results of the electrochemical measurement proved that decoration of N-CMK3 with a suitable amount of SnO
2
enhanced the specific capacitance of the electrodes. Among the SnO
2
@N-CMK3 (SNC) samples under investigation, 15-SNC with 15 wt% SnO
2
delivered outstanding electrochemical performance with respect to specific capacitance and cycling stability. At a scan rate of 5 mV s
−1
, 15-SNC exhibited superspecific capacitance up to 344 F g
−1
and long-term cyclability at a scan rate of 50 mV s
−1
with 92.4% retention of its initial specific capacitance of 161 F g
−1
after 5000 cycles.
A unique material comprising mesoporous carbon decorated with tin oxide was synthesised by facile incipient wetness impregnation for enhanced charge storage.
210
Po activity was investigated in the eleven organs of two marine fish species, bigeye scad and greater lizardfish at Binh Thuan, Vietnam by alpha-spectrometry. The
210
Po concentration ...significantly varied among organs, where the highest
210
Po activity of 278 and 512 Bq/kg.w.wt were observed in intestine and lowest of 12.9 and 2.8 Bq/kg.w.wt in muscle tissue of those fish species organs, respectively. The
210
Po bioconcentration factor (BCF) ranged from 9.3 × 10
3
to 20 × 10
4
for bigeye scad and from 2.0 × 10
3
to 37 × 10
4
for greater lizardfish. The BCF and annual committed effective dose values showed a high radiation potential and higher than the limit value of 1000 μSv/y.
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