In this paper, the development and application of the radial basis function-finite difference (RBF-FD) method and the RBF-finite difference time domain (RBF-FDTD) method for solving electrical ...transient problems in power systems that are defined by the time-dependent ordinary differential equations (ODEs) and the time-dependent partial differential equations (PDEs), respectively, are presented. RBFs such as Gaussian (GA), Multiquadric (MQ), Inverse Quadric (IQ), and Inverse Multiquadric (IMQ) are used in these numerical methods to formulate the central finite difference approximations of the first- and second-order derivatives of a function. The algorithm of selecting “optimal” shape parameters for our basis functions is also applied, specifically to increase the accuracy of the suggested methods with regard to high accuracy needs. Finally, the accuracy, effectiveness, and applicability of our new approaches are evaluated through simulations of the switching transient voltages on a typical electrical circuit and a 220 kV single-phase transmission line, lightning-induced voltages on a 110 kV single-phase overhead distribution line, and transient voltages along two horizontal grounding electrodes excited by lightning impulse sources. The obtained numerical results demonstrate that our proposed RBF-based numerical approaches compare favorably to the traditional numerical methods.
This article considers a problem of tracking, convergence of disturbance observer (DO) based optimal control design for uncertain surface vessels (SVs) with external disturbance. The advantage of ...proposed optimal control using adaptive/approximate reinforcement learning (ARL) is that consideration for whole SVs with only one dynamic equation and without conventional separation technique. Additionally, thanks to appropriate disturbance observer, the attraction region of tracking error is remarkably reduced. On the other hand, the particular case of optimal control problem is presented by directly solving for the purpose of choosing the suitable activation functions of ARL. Furthermore, the proposed ARL based optimal control also deals with non-autonomous property of closed tracking error SV model by considering the equivalent system. Based on the Lyapunov function candidate using optimal function and quadratic form of estimated error of actor/critic weight, the stability and convergence of the closed system are proven. Some examples are given to verify and demonstrate the effectiveness of the new control strategy.
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•The proposed control scheme is implemented by a framework of a DO and a RL based optimal control strategy without conventional separation technique.•The proposed controller develops the simultaneous tuning of RL strategy for guaranteeing the tracking problem of non-autonomous closed systems.•The stability and convergence of learning method are strictly proven from optimality principle and Lyapunov theorem on stability. Moreover, the method of choosing activation functions of RL is approached and verified based on the solution of a special case of optimal control problem.
This study aims to find the interaction between ionome and metabolome profiles of
Pteris vittata
L., an arsenic hyperaccumulator plant, to reveal its metal tolerance mechanism. Therefore, at the ...Pb–Zn mining sites located in Thai Nguyen province, Vietnam, where these species dominate, soil and plant samples were collected. Their multi-element compositions were analyzed using inductively coupled plasma mass spectrometry (ICP-MS) and thus referred to as the “ionomics” approach. In parallel, the widely targeted metabolomics profiles of these plant samples were performed using liquid chromatography-tandem mass spectrometry (UPLC-QqQ-MS). Nineteen elements, including both metals and nonmetals, were detected and quantified in both tissues of thirty-five plant individuals. A comparison of these elements’ levels in two tissues showed that above-ground parts accumulated more As and inorganic P, whereas Zn, Pb, and Sb were raised mostly in the under-ground samples. The partial least squares regression (PLSR) model predicting the level of each element by the whole metabolome indicated that the enhancement of flavonoids content plays an essential contribution in adaptation with the higher levels of Pb, Ag, and Ni accumulated in the aerial part, and Mn, Pb in subterranean part. Moreover, the models also highlighted the effect of Mn and Pb on the metabolic induction of adenosine derivatives in subterranean parts. At the same time, the model presented the most contribution of As to the metabolisms of the amino acids of this tissue. On those accounts, the developed integration approach linking the ionomics and metabolomics data of
P. vittata
improved the understanding of the molecular mechanism of hyperaccumulation characteristics and provided markers that could be targeted in future investigations.
Using a theoretical prediction based on space-filling calculations and Metropolis Monte Carlo simulation, we investigate the assembly behavior of binary colloid-droplet mixtures into crystal ...structure types. Colloid-colloid and droplet-droplet pair interactions are hard-core repulsions. The colloid-droplet interaction is a selective and directional attraction that induces the Pickering emulsion. The colloids are decorated with eight regularly arranged attractive patches where the droplets can be adsorbed. Both in the space-filling calculation and with the simulation, we find two assembled crystal structures with the calcium fluoride (CaF
2
) and cesium chloride (CsCl), depending on the droplet to colloid diameter ratio,
q
=
σ
d
/
σ
c
with
σ
d
the diameter of the droplet and
σ
c
the diameter of the colloid. More precisely, in the simulations, when
q
ranges from 0.779 to 1.262, CsCl is found. For
0.2
<
q
<
0.779
or
q
>
1.26
the possible structure is CaF
2
. A discrepancy between the theory and simulation seems to be at high
q
values. We note that although colloidal crystals of CaF
2
and CsCl are known as potential candidates for photonic applications, CaF
2
has not yet been fabricated experimentally, while CsCl seems thermodynamically unstable or stable at a very narrow range of the size ratio. Therefore, our findings can be helpful to synthesize these structures.
An ultrahigh-performance liquid chromatography in combination with high-resolution mass spectrometry Thermo Q-Extractive Focus Orbitrap MS has been introduced for analysis of multiclass pesticides in ...vegetable samples collected in Hanoi, Vietnam. Multiclass pesticides were separated on the Thermo Hypersil Gold PFP column utilizing a gradient of the mobile phase consisting of 5 mM ammonium formate, 0.1% formic acid in deionized water, and methanol. The target analytes were detected in the full-scan mode on Thermo Scientific Q-Exactive Focus Orbitrap MS for quantitation at the optimum operating conditions. These conditions included, but not limit to, the resolution of 70000 at the full width at half maximum in both positive and negative mode, mass range from 80 to 1000 m/z, and optimized parameters for the heated electrospray ionization source. The identification of the analytes in real samples was based on retention times, mass to charge ratios, mass accuracies, and MS/MS spectra at the confirmation mode with the inclusion list of target analytes. The mass accuracies of target analytes were from −4.14 ppm (dinotefuran) to 1.42 ppm (cinosulfuron) in the neat solvent and from −3.91 ppm (spinosad D) to 1.29 ppm (cinosulfuron) in the matrix-matched solution. Target analytes in the vegetable-based matrix were extracted by the QuEChERS method. Some critical parameters of the analytical method such as linearity, repeatability, limit of detection, and limit of quantitation have been evaluated and implemented. Excellent LOD and LOQ of the developed method were achieved at the range of 0.04–0.85 and 0.13–2.9 μg·kg−1, respectively. Intraday and interday repeatability of the analytical signal (peak area, n=6) of the developed method were below 3% and 10%, correspondingly. The matrix effect, extraction recovery, and overall recovery were fully investigated by spiking experiments. Experimental results demonstrated that the ionization suppression or enhancement was the main contribution on the overall recoveries of target analytes. Finally, the in-house validated method was applied to pesticides screening in vegetables samples in local villages in Hanoi, Vietnam. The concentrations of all target analytes were below limit of quantitation and lower than US-FDA or EU maximum residue levels.
Background:
Little is known about video-assisted thoracoscopic surgery in the Nuss procedure (VATS-NUSS) and its postoperative outcomes in the resource-scarce conditions in clinical practice such as ...Vietnam. Available evidence in the literature was mostly reported from large institutions in developed countries. Hence, this study was conducted to review our initial large single-center experience in the use of the VATS-NUSS for patients with pectus excavatum (PE) within 5 years.
Methods:
Data from 365 consecutive PE patients between January 2015 and December 2019 who were surgically treated with VATS-NUSS were retrospectively analyzed.
Results:
Of 365 patients, median age at operation was 15.61 ± 3.73 years (range = 5–27 years), most being child and adolescent. Three hundred nine patients (84.65%) were male. PE was commonly detected at puberty (
n
= 328, 89.9%). Postoperatively, early complications consisted of pneumothorax (
n
= 5, 1.37%), pleural bleeding/pleural fluid (
n
= 2, 0.55%), pleural hematoma (
n
= 1, 0.27%), pneumonia (
n
= 1, 0.27%), surgical wound infection (
n
= 1, 0.27%), incision fluid accumulation (
n
= 3, 0.82%), metal bar infection (
n
= 1, 0.27%), atelectasis (
n
= 3, 0.82%), and fever (
n
= 8, 2.19%). Late complications included surgical wound infection (
n
= 2, 0.55%), metal bar deviation (
n
= 5, 1.37%), metal bar allergy (
n
= 10, 2.74%), recurrent PE (
n
= 2, 0.55%), and persistent PE (
n
= 5, 1.37%). No deaths occurred. In 175 patients (47.95%) experiencing bar removal, mean operative time for bar removal was 34.09 ± 10.61 min, and the length of hospitalization following bar removal was 2.4 ± 1.34 days; the most frequent complication was pneumothorax (
n
= 19, 10.85%). One wound infection and one incision fluid accumulation happened following bar removal. Favorable midterm to long-term postoperative outcomes were achieved.
Conclusions:
From the beginning of the Vietnamese surgeons' experience, VATS-NUSS application obtained favorable outcomes with minimizing the occurrence of serious intraoperative and postoperative complications. Current rare evidence enables to give a real picture in the application, modification, and development of VATS-NUSS in the countries having similar resource-scarce conditions.
The use of 3D-printed Patient-Specific Instruments (PSI) has been investigated to enhance the postoperative functional results in total hip arthroplasty (THA) and has been recognized as an innovative ...approach for the optimal alignment of hip implant components. Point-of-care production is gradually becoming the norm for PSI manufacturing. The purpose of this article is to assess the accuracy and safety of PSI for total hip arthroplasty performed at the point-of-care in Vietnam.
34 THA cases were assessed in this prospective study. A template for the size and orientation of the implant and the design of the PSI was generated using data from preoperative 3D computed tomography (CT) scanning of the lower limb. The principal surgeon determined the implants' position and PSI design directly using the software. The PSI is then produced using a 3D-compatible resin printer in our manufacturing hospital. The PSI, consisting of an acetabulum and a femoral component placed press-fit on the bony surface, guided surgeons to precisely ream the acetabulum and cut the femoral neck according to the pre-planned plane. Postoperative CT scanning was obtained and superimposed onto the 3D model of the implant to evaluate the accuracy of the procedure by comparing the orientation values of the cup and the alignment of the stem between the planned and the actual results. Intra- and postoperative clinical parameters of surgery, including surgical time, intra-operative blood loss, complications, and the first ambulation, were also recorded to evaluate the safety of the surgery.
The preparation for PSI required an average of 3 days. 94% of cup size and 91% of stem size were correctly selected. The mean values of postoperative inclination and anteversion were 44.2° ± 4.1° and 19.2° ± 5.6°, respectively. 64.7% of cases deviated from planned within the ± 5
range and 94.1% within the ± 10° range. There was no significant statistical difference between the planned and the achieved values of stem anteversion, osteotomy height, and leg length discrepancy (p > 0.05). The average surgical time was 82.5° ± 10.8 min, and the intraoperative blood loss was estimated at 317.7° ± 57.6 ml. 64.7% of patients could walk on the day of surgery. There were no complications reported.
The point-of-care manufactured PSI is a useful solution for improving the accuracy of total hip arthroplasty surgery, especially in restoring implant orientation and reducing leg length discrepancy. However, long-term clinical follow-up evaluation is needed to confirm the efficacy and safety of this approach.
In this study, the relationship between heavy metals (HMs) concentrations in soils and several weeds including Cyclosorus parasiticus, Dicranopteris linearis, Pityrogramma calomelanos, and Pteris ...vittata in three mining sites (Cam Gia (Thai Nguyen city), Tan Long (Dong Hy district), and Ha Thuong (Dai Tu district)) in Thai Nguyen province, Vietnam, have been investigated. The levels of HMs varied among soil origins and showed the contaminations of As, Cu, and Pb in soil samples collected in Dong Hy and Dai Tu districts. In addition, the HM distribution and cocontamination phenomena in different soils significantly affected the HM residues and transportation abilities into different species as well as tissues. Moreover, based on the analysis of bioaccumulation factor (BF) and translocation factor (TF), C. parasiticus and D. linearis were found potentially for phytoextraction by roots, while P. calomelanos and P. vittata were suitable for hyperaccumulation in shoots and leaves. Consequently, the strongest antioxidant property by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion (SRSA) radical scavenging assays were demonstrated in the methanol root extracts of C. parasiticus and P. vittata, respectively. In conclusion, the correlation among HM in soils and tissues with antioxidant property allows us to hypothesize that the presence of these elements can enhance the antioxidant activity of plant extracts, suggesting to apply the weeds in phytoremediation as well as in phytomedicine.
The tech sector has been growing at a rapid speed, demanding a higher level of expertise from its labor force. New skills and programming languages are introduced and required by the industry every ...day, while the university courses are not updated adequately. Finding the high-demand skills and relevant courses to study has become essential to both students and faculty members at tech universities, which leads to a growing research interest in building an intelligence system to support decision making. Leveraging recent development in Natural Language Processing, we built an NLP-based course recommendation system specifically for the computer science (CS) and information technology (IT) fields. In particular, we built (1) a Named Entity Recognition (CSIT-NER) model to extract tech-related skills and entities, then used these skills to build (2) a personalized multi-level course recommendation system using a hybrid model (hybrid CSIT-CRS). Our CSIT-NER model, trained and fine-tuned on a large corpus of text extracted from StackOverflow and GitHub, can accurately extract the relevant skills and entities, outperforming state-of-the-art models across all evaluation metrics. Our hybrid CSIT-CRS can provide recommendations on multiple individualized levels of university courses, career paths with job listings, and industry-required with suitable online courses. The whole system received good ratings and feedback from users from our survey with 201 volunteers who are students and faculty members of tech universities in Australia and Vietnam. This research is beneficial to students, faculty members, universities in CS/IT higher education sector, and stakeholders in tech-related industries.
•An NLP-based RecSys to personalise course/job recommendation for CS/IT students and curriculum design for faculty members.•A novel domain-specific named entity recognition model to extract keywords and analyse the CS/IT course/job description.•A user-friendly and automatic web application to deploy our models on the cloud and integrate into university systems.
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•The polyoxygenated sterols of the Vietnamese Menella woodin were investigated.•Four new polyoxygenated steroids were isolated and structurally elucidated.•Three isolated steroids ...have shown a reduction of ROS levels in macrophages.
Four new polyoxygenated sterol derivatives (1–4) along with the compounds (5–7) previously known from other biological sources were isolated from the gorgonian Menella woodin, collected from the Vietnamese waters. Structures of 1–4 were elucidated by the detailed NMR spectroscopic and mass-spectrometric analyses as well as comparison with those reported in literature data. Compounds 1, 4, and 6 decrease the production of reactive oxygen species (ROS) by the murine macrophages of RAW 264.7 line at induction by endotoxic lipopolysaccharide (LPS) from Escherichia coli.
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