244 research outputs found
Geometry-Aware Coverage Path Planning for Depowdering on Complex 3D Surfaces
This paper presents a new approach to obtaining nearly complete coverage
paths (CP) with low overlapping on 3D general surfaces using mesh models. The
CP is obtained by segmenting the mesh model into a given number of clusters
using constrained centroidal Voronoi tessellation (CCVT) and finding the
shortest path from cluster centroids using the geodesic metric efficiently. We
introduce a new cost function to harmoniously achieve uniform areas of the
obtained clusters and a restriction on the variation of triangle normals during
the construction of CCVTs. Here, we utilize the planned VPs as cleaning
configurations to perform residual powder removal in additive manufacturing
using manipulator robots. The self-occlusion of VPs and ensuring collision-free
robot configurations are addressed by integrating a proposed optimization-based
strategy to find a set of candidate rays for each VP into the motion planning
phase. CP planning benchmarks and physical experiments are conducted to
demonstrate the effectiveness of the proposed approach. We show that our
approach can compute the CPs and VPs of various mesh models with a massive
number of triangles within a reasonable time.Comment: 8 pages, 8 figure
CHARACTERISTICS OF 7th GRADERS IN THAI NGUYEN CITY (VIETNAM) FROM THE PERSPECTIVE OF DIFFERENTIAL LEARNERS IN PHYSICAL EDUCATION ACTIVITIES
Differentiated-oriented physical education (PE) helps learners to participate in learning activities with content and form suitable to their individual characteristics. Capturing the individual characteristics of learners is of great significance in the process of physical education. Through document research, interviews, pedagogical observations and examination, the research assesses the characteristics of 7th graders in Thai Nguyen City from the perspective of differential learners in Physical Education. This is an important basis for organizing physical education activities in the direction of differentiation for 7th graders in Thai Nguyen City.Ā Article visualizations
Character Time-series Matching For Robust License Plate Recognition
Automatic License Plate Recognition (ALPR) is becoming a popular study area
and is applied in many fields such as transportation or smart city. However,
there are still several limitations when applying many current methods to
practical problems due to the variation in real-world situations such as light
changes, unclear License Plate (LP) characters, and image quality. Almost
recent ALPR algorithms process on a single frame, which reduces accuracy in
case of worse image quality. This paper presents methods to improve license
plate recognition accuracy by tracking the license plate in multiple frames.
First, the Adaptive License Plate Rotation algorithm is applied to correctly
align the detected license plate. Second, we propose a method called Character
Time-series Matching to recognize license plate characters from many
consequence frames. The proposed method archives high performance in the
UFPR-ALPR dataset which is \boldmath accuracy in real-time on RTX A5000
GPU card. We also deploy the algorithm for the Vietnamese ALPR system. The
accuracy for license plate detection and character recognition are 0.881 and
0.979 @.5 respectively. The source code is available at
https://github.com/chequanghuy/Character-Time-series-Matching.gi
SITUATION OF THE TEACHING PHYSICAL EDUCATION FOR SEVENTH GRADERS IN THAI NGUYEN CITY FROM THE PERSPECTIVE OF DIVISION IN EDUCATION
Differentiation-oriented physical education (PE) helps learners participate in learning activities with content and forms suitable to their personal characteristics. Through researching documents, interviews, and pedagogical observations, the project explores the current status of teaching physical education to 7th graders in Thai Nguyen City from the perspective of division in education. The results of this research are an important practical basis to propose measures to organize teaching physical education in a differentiated direction for 7th graders in Thai Nguyen City.Ā Article visualizations
AMMONIA-REMOVAL EFFICIENCY OF A NOVEL ACINETOBACTER CALCOACETICUS STRAIN ISOLATED FROM INDUSTRIAL WASTEWATER OF NINH BINH COAL NITROGENOUS FERTILIZER PLANT
Ammonium removal from wastewaters has recently became a major concern of fertilizer manufacturers and industrial zones in Vietnam. Using aerobic ammonium remover may be a appreciate solution for reduction of treatment cost. This study describes the isolation and characterization of a novel bacterium for ammonium removal under aerobic conditions. Twelve ammonium remover strains were isolated from wastewater of a local fertilizer industry. The isolated strains were initially screened using solid media for their nitrifying activities. Among them two of the bacteria displayed the highest removal of ammonium without much accumulation of nitrite and nitrate. The isolates were identified as Acinetobacter based on biochemical characteristis and 16S rRNA sequence. One of these two isolates, Acinetobacter calcoaceticus A8 strain, showed 88% ammonium removal from industrial fertilizer wastewater
Experimental modal analysis and optimal design of cabās isolation system for a single drum vibratory roller
The purpose of this paper is to solve problems about cabās low-frequency shaking in the direction of forward motion when vibratory roller operates. To solve this problem, a modal test for a single-drum vibratory roller is carried out by the Belgium LMS dynamic testing which is used to identify the model parameters and find out the natural frequency of the vehicle. A Finite Element Analysis (FEA) simulation is carried out to find out the reasons causing the cabās low-frequency shaking. The model simulation results are found to be in good agreement with the experimental results. Finally, the design parameters of cabās isolation system are optimized to reach the maximum value of the first-order natural frequency in order to avoid resonance vibration for cab at low frequency and reduce cabās low-frequency shaking
Structure elucidation off seven steroids from Sinularia conferta.
Seven steroids were isolated from the methanol extract of the soft corals Sinularia conferta. These steroids were elucidated as 7a-methoxyergosta-5,24(28)-diene-3b-ol (1), ergosta-5-ene-3Ī²,7Ī±-diol (2), 3Ī²,7Ī±-dihydroxyergosta-5,24(28)-diene (3), 3Ī²-hydroxyergosta-5,24(28)-diene-7-one (4), ergosta-24(28)-ene-3Ī²,5Ī±,6Ī²-triol-6-acetate (5), ergosta-24(28)-ene-3Ī²,5Ī±,6Ī²-triol (6), and ergosta-3Ī²,5Ī±,6Ī²-triol (7) by 1D and 2D-NMR experiments and comparison with reported data. Keywords. Sinularia conferta, Alcyoniidae, soft coral, steroid
Vectors and malaria transmission in deforested, rural communities in north-central Vietnam
Background: Malaria is still prevalent in rural communities of central Vietnam even though, due to deforestation, the primary vector Anopheles dirus is uncommon. In these situations little is known about the secondary vectors which are responsible for maintaining transmission. Basic information on the identification of the species in these rural communities is required so that transmission parameters, such as ecology, behaviour and vectorial status can be assigned to the appropriate species
Synthesis and biological evaluation of shikimic acid derivatives
From shikimic acid, new series of oseltamivir analogues containing either ether sulfur or ether oxygen at C-3 position were prepared and evaluated for their biological activities. This is the first report on synthesis of oseltamivir analogues with ether sulfur at C-3. Except for compounds 4d, 4f, 7c and 7d, the remaining compounds were found to be active against MCF-7, LU-1 and KB cell lines. As oseltamivir had no cytotoxicity against different cell lines such as MCF-7, LU-1, KB, MDCK, MRC-5, VERO, MK and 293, the modification of alkyl groups at C-3 of the oseltamivir ring framework could significantly increase the cytotoxicity for this class of compounds. Loss of neuraminidase inhibition activity of these synthetic oseltamivir analogues suggested that the alkyl ether groups at C-3 should be critical for their anti-neuraminidase activity
A modern purification by accelerated solvent extraction and centrifugal partition chromatography and biological evaluation of capsaicin from Capsicum chinense
A special alkaloid compound known as capsaicin, which can only be found in the fruit of the Capsicum plant, was isolated and tested for its anti-inflammatory activity. The purpose of this work is to establish a simple and quick approach for capsaicin purification utilizing centrifugal partition chromatography (CPC) as well as an effective method - accelerated solvent extraction (ASE), for extracting capsaicin from Capsicum chinense. After purification, capsaicin was validated by HPLC-DAD at 281 nm to be > 90% purity. The in vivo anti-inflammatory activity of the isolated capsaicin was also investigated, and the IC50 value of the capsaicin was determined to be 57.61 Āµg/mL. The current work emphasizes how an ASE and CPC system may combine to extract high-purity capsaicin from Capsicum chinense, which have the anti-inflammatory activity, as we evaluated in the experiment
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