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

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$96.7\%$ 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 $mAP^{test}$@.5 respectively. The source code is available at https://github.com/chequanghuy/Character-Time-series-Matching.gi

Literature Review of Knowledge Sharing and Issues Raised for Vietnamese Universities

This study aims to review previous studies in the field of knowledge sharing. Data being used in this study was collected from researches related to the topic of knowledge sharing. We summarize literature on knowledge sharing in terms of (i) Necessity of knowledge sharing, (ii) Supporting from information and communication technology tools (ICT), (iii) Context of knowledge sharing, (iv) Participants knowledge sharing, (v) Receiver knowledge and (vi) advantages and disadvantages when participating in knowledge sharing. Some implications are recommended for Vietnamese universities to better support knowledge sharing activities in Vietnam and around the world. Keywords: Knowledge management, Knowledge sharing, Information technology, Management information system. DOI: 10.7176/JESD/10-18-17 Publication date:September 30th 201

Study of the Correlation Between Bronchial Hyperresponsiveness and Exhaled Nitric Oxide in Subjects with Suspected Symptoms of Asthma

Background: Bronchial hyperresponsiveness (BHR) is one of main features of asthma within chronic inflammation and reversible bronchoconstriction. Actually, methacholine challenge is useful method to detect BHR in subjects with suspected asthma symptoms. However, this method has some limitations due to its safety and side effects. The measure of exhaled nitric oxide (NO) demonstrates currently as the alternative method for methacholine challenge. Methods: Ninety-five subjects had at least one of the following symptoms were included in this study: wheezing or chest tightness during exercise, chronic cough, or nocturnal coughing. They were divided into two groups depending on the positivity or negativity of BHR. Lung function test, exhaled NO measurement, and methacholine challenge were done for each study subject. Results: There were no significant differences between two groups for age and male/female ratio (41 ± 22 vs 38 ± 23 years old and 0.9 vs 1.1; P > 0.05 and P > 0.05; respectively). The percentage of wheezing and nocturnal coughing in subjects with positive BHR (BHR+) was significantly higher than that in subjects with negative BHR (BHR-: 70.9% and 64.5% vs 31.2% and 45.1%; P<0.001 and P<0.01; respectively). FENO measured at 50 mL/s in subjects with BHR+ was significantly higher subjects with BHR- (36 ± 10 ppb vs 11 ± 9 ppb; P<0.001). There was a significant correlation between FENO-50 mL/s and methacholine dose in subjects with BHR+ (R= -0.695; P<0.001). FENO-50 mL/s at 35 ppb had 86.7% of sensibility and 82.9% of specificity for diagnosis of BHR. Conclusion: FENO is a useful biomarker for diagnosis of asthma in subjects with suspected symptoms of asthma. FENO level has a high sensitivity and specificity for screening out subjects with BHR. The measurement of exhaled NO may be an alternative method for detecting BHR in diagnosis of asthma in clinical practice

Design a cryptosystem using elliptic curves cryptography and Vigenère symmetry key

In this paper describes the basic idea of elliptic curve cryptography (ECC) as well as Vigenère symmetry key. Elliptic curve arithmetic can be used to develop elliptic curve coding schemes, including key exchange, encryption, and digital signature. The main attraction of elliptic curve cryptography compared to Rivest, Shamir, Adleman (RSA) is that it provides equivalent security for a smaller key size, which reduces processing costs. From the theorical basic, we proposed a cryptosystem using elliptic curves and Vigenère cryptography. We proposed and implemented our encryption algorithm in an integrated development environment named visual studio 2019 to design a safe, secure, and effective cryptosystem

Day-night variation and size distribution of water-soluble inorganic ions in particulate matter in Ulsan, South Korea

In the present study, 11 size classes of particulate matter were collected from a semi-rural site in the industrial city of Ulsan, South Korea in 2019 to investigate the size distribution and day-night variation of water-soluble inorganic ions (WSIIs). Approximately 70% of the detected WSIIs were found in fine particles, with Na+, Ca (2+), Cl-, and NO3- dominant (similar to 70%) in coarse particles and SO42-, NO3-, and NH4+ (SNA) dominant (similar to 70%) in fine particles. Monthly variation in total WSIIs was observed, with the highest average concentration found in April for both coarse (2.71 mu g/m(3)) and fine particles (5.75 mu g/m(3)). Given that this month is characterized by prevailing southeasterly winds, these high levels may represent the adverse effects of industrial activity. Coefficients of divergence for individual WSIIs exhibited large variability, which is indicative of significant day-night differences in meteorology, chemistry, and source contributions. The size distributions of Na+, K+, F-, Cl-, NO3-, and SO42- were bimodal, while Mg2+, Ca2+, and NH4+ were unimodal. Peaks were generally found at 1.8-5.6 mu m and 0.18-0.56 mu m for coarse and fine particles, respectively. By plotting the linear relationship between the mole charge ratios of SNA, we found that coarse NO3- particles were mainly the result of heterogeneous reactions between HNO3 and sea salts or crustal species, while the homogeneous reaction of HNO3 and NH3 played a crucial role in the formation of fine NO3- particles. In conclusion, though day-night variation in WSIIs was apparent, especially in SNA, the formation pathways for both coarse and fine particles were similar for day and night. Based on the verification of the formation mechanisms for WSIIs at this semi-rural site, the influence of industrial activity on the secondary formation of PM in urban and industrial areas can be investigated further

Biocontrol of Alternaria alternata YZU, a causal of stem end rot disease on pitaya, with soil phosphate solubilizing bacteria

Stem end rot is the most destructive disease caused by Alternaria alternata YZU in pitaya-growing regions of Vietnam. This study was conducted to characterize antagonistic phosphate-solubilizing bacteria (PSB) from rhizosphere soil for their biocontrol activities against A. alternata YZU and evaluate the effect of temperature, pH, and water activity on that antagonism. Among seven PSB isolated from 45 rhizosphere soil samples, PSB31 (identified as Bacillus sp. strain IMAU61039, Accession number: MF803700.1) exhibited the highest antagonistic activity against A. alternata YZU with an average inhibition diameter of 0.65 ± 0.05 cm. The results also show that the strain PSB31 controlled the mycelial growth of A. alternata YZU by secreting antifungal metabolites. The most potent inhibitory activity was identified under in vitro conditions of 25 °C, pH 7, and aw 1. The isolated PSB31 could be a potential biological control agent against A. alternata YZU

Measuring the progress of the timeliness childhood immunization compliance in Vietnam between 2006-2014: A decomposition analysis

Vietnam launched the national Expanded Program on Immunization in 1981. Since then, this program has contributed signi cantly to the improvement of child health and to the reduction of child mortality rate. Despite of the fact that the coverage of the national EPI keeps expanding, the number of children who complied with the recommended immunization schedule remains low. This article studies the progress of the timeliness childhood immunization compliance among children between 0-5 years of age in Vietnam from 2006 to 2014 and analyzes the socio-economic factors that account for the changes of the compliance rate during this period. The dataset is extracted from the Multiple Indicator Cluster Survey in 2006 and 2014. We rst identify the socio-economic factors that impact on the vaccination compliance rate using a logistic regression model. Next, we apply the decomposition method to determine the contribution of each factor on the evolution of the timeliness childhood immunization compliance. The progress of the timeliness childhood immunization has been positive and the major contribution comes from the structure e ect (unmeasured e ect). Rural areas show a stronger improvement as of 2014. Among the socio-economic factors, mother education and birth order are the ones that have the larger in uence on the childhood immunization compliance rate. However, these factors have di erent implications in urban and rural areas. These ndings are critical to the current context of Vietnam where the government is designing a strategy focusing on the e ectiveness rather than the traditional coverage indicator

Measuring the progress of the timeliness childhood immunization compliance in Vietnam between 2006-2014: A decomposition analysis

Vietnam launched the national Expanded Program on Immunization in 1981. Since then, this program has contributed signi cantly to the improvement of child health and to the reduction of child mortality rate. Despite of the fact that the coverage of the national EPI keeps expanding, the number of children who complied with the recommended immunization schedule remains low. This article studies the progress of the timeliness childhood immunization compliance among children between 0-5 years of age in Vietnam from 2006 to 2014 and analyzes the socio-economic factors that account for the changes of the compliance rate during this period. The dataset is extracted from the Multiple Indicator Cluster Survey in 2006 and 2014. We rst identify the socio-economic factors that impact on the vaccination compliance rate using a logistic regression model. Next, we apply the decomposition method to determine the contribution of each factor on the evolution of the timeliness childhood immunization compliance. The progress of the timeliness childhood immunization has been positive and the major contribution comes from the structure e ect (unmeasured e ect). Rural areas show a stronger improvement as of 2014. Among the socio-economic factors, mother education and birth order are the ones that have the larger in uence on the childhood immunization compliance rate. However, these factors have di erent implications in urban and rural areas. These ndings are critical to the current context of Vietnam where the government is designing a strategy focusing on the e ectiveness rather than the traditional coverage indicator