Vietnam Academy of Science and Technology: Journals Online
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TRAO ĐỔI: VỀ CÔNG TRÌNH NGHIÊN CỨU TÍNH TOÁN “ĐỘ TIN CẬY TỔNG THỂ” ĐĂNG TRÊN TẠP CHÍ KHOA HỌC VÀ CÔNG NGHỆ BIỂN SỐ 3 TẬP 10 NĂM 2010
No full textMục đích của bài viết này là chỉ ra rằng phương pháp tính “Độ tin cậy tổng thể” trong bài báo đăng trên Tạp chí Khoa học và Công nghệ Biển Số 3 Tập 10 (2010) chỉ là một đề xuất, chưa được chứng minh. Tác giả bài báo đã sử dụng định lý nhân xác suất để chứng minh một mệnh đề, trong đó không thỏa mãn giả thiết về sự xuất hiện đồng thời của hai sự kiện ngẫu nhiên bền và mỏi. Ngoài ra bài viết này còn chỉ ra việc đánh giá an toàn của công trình bằng “Độ tin cậy tổng thể” là không hợp lý. Vì vậy, theo ý kiến tác giả bài viết, kết quả nghiên cứu về “Độ tin cậy tổng thể” nêu trên không thể áp dụng trong nghiên cứu, đào tạo và ứng dụng, đặc biệt là vào các lĩnh vực liên quan đến chủ quyền Quốc gia như các công trình biển, đảo
DEVELOPMENT OF HIGH-PERFORMANCE AND LARGE-SCALE VIETNAMESE AUTOMATIC SPEECH RECOGNITION SYSTEMS
Get PDFAutomatic Speech Recognition (ASR) systems convert human speech into the corresponding transcription automatically. They have a wide range of applications such as controlling robots, call center analytics, voice chatbot. Recent studies on ASR for English have achieved the performance that surpasses human ability. The systems were trained on a large amount of training data and performed well under many environments. With regards to Vietnamese, there have been many studies on improving the performance of existing ASR systems, however, many of them are conducted on a small-scaled data, which does not reflect realistic scenarios. Although the corpora used to train the system were carefully design to maintain phonetic balance properties, efforts in collecting them at a large-scale are still limited. Specifically, only a certain accent of Vietnam was evaluated in existing works. In this paper, we first describe our efforts in collecting a large data set that covers all 3 major accents of Vietnam located in the Northern, Center, and Southern regions. Then, we detail our ASR system development procedure utilizing the collected data set and evaluating different model architectures to find the best structure for Vietnamese. In the VLSP 2018 challenge, our system achieved the best performance with 6.5% WER and on our internal test set with more than 10 hours of speech collected real environments, the system also performs well with 11% WE
On the Performance of a Simple Approximation Algorithm for the Longest Path Problem
Get PDFThe longest path problem is known to be NP-hard. Moreover, they cannot be approximated within a constant ratio, unless . The best known polynomial time approximation algorithms for this problem essentially find a path of length that is the logarithm of the optimum.In this paper we investigate the performance of an approximation algorithm for this problem in almost every case. We show that a simple algorithm, based on depth-first search, finds on almost every undirected graph a path of length more than and so has performance ratio less than .
Developing algorithm for estimating chlorophyll-a concentration in the Thac Ba Reservoir surface water using Landsat 8 Imagery
No full textThis study aims at developing a regional algorithm to quantify chlorophyll-a concentration (Chla) in the Thac Ba Reservoir surface-water using Landsat 8 imagery basing on in-situ data of Chla and above-water reflectance taken in both dry and rainy seasons 2018. In situ datasets obtained from 30 water sampling sites show a strong correlation (R2=0.73) with the reflectance ratio of two Landsat 8 (L8) bands, the green band (band 3: B3) versus the red band (band 4: B4), B3 / B4, by an exponential equation. The algorithm for estimating Chla using this ratio was well-matched up the validation using multiple-dates in-situ datasets (R2 = 0.82; RMSE ~ 5%) and was then applied to L8 images level 2 acquired in both dry and rainy seasons to understand the spatiotemporal distribution of Chla over the reservoir. Obtained maps of Chla present clearly two trends: (1) Chla in the reservoir water in the dry season (averaged at 15.3 mg/m3) is relatively lower than those in the rainy season (averaged at 17.0 mg/m3); (2) In both seasons, Chla increased from water area in front of the Chay River mouth to the center of the reservoir. The algorithm and method outlined in this study could be applied to monitoring Chl in other inland waters having similar features as the Thac Ba Reservoir water.ReferencesAPHA, 1998. Standard Methods for the Examination of Water and Wastewater, 20th edition. American Public Health Association, Washington DC, 1220p.Bac N.A., Viet N.D., Ha N.T.T., Huong H.T.T., 2017. Identifying eutrophication status of shallow waters based on estimated trophic state index from satellite data. Journal of Science and Technology, 55(4C), 85-89.Bernardo N., Watanabe F., Rodrigues T., Alcântara E., 2017. Atmospheric correction issues for retrieving total suspended matter concentrations in inland waters using OLI/Landsat-8 image. Advances in Space Research, 59(9), 2335-2348.Boucher J., Weathers K.C., Norouzi H., Steele B., 2018. Assessing the effectiveness of Landsat 8 chlorophyll a retrieval algorithms for regional freshwater monitoring. Ecological Applications, 28(4), 1044-1054.Carlson R.E., 1977. A trophic state index for lakes1. Limnology and oceanography, 22(2), 361-369.Carlson R.E., Simpson J., 1996. A coordinator’s guide to volunteer lake monitoring methods. North American Lake Management Society, 96, 305.DWR - Directorate of Water Resource, 2017. Report on weather conditions, water supplies, flood control and irrigations security No. 49/BC-TCTL-QLCT to Minister of Agriculture and Rural Development (in Vietnamese) on October 16th, Hanoi, Vietnam. Gholizadeh M.H., Melesse A.M., Reddi L., 2016. A comprehensive review on water quality parameters estimation using remote sensing techniques. Sensors, 16(8), 1298.Gitelson A., Stark R., Oron G., Dor I., 1997. Monitoring of polluted water bodies by remote sensing. IAHS Publications-Series of Proceedings and Reports-Intern Assoc Hydrological Sciences, 242, 181-188.Ha N.T.T., Koike K., 2011. Integrating satellite imagery and geostatistics of point samples for monitoring spatio-temporal changes of total suspended solids in bay waters: application to Tien Yen Bay (Northern Vietnam). Frontiers of Earth Science, 5(3), 305.Kutser T., 2009. Passive optical remote sensing of cyanobacteria and other intense phytoplankton blooms in coastal and inland waters. International Journal of Remote Sensing, 30(17), 4401-4425.Kutser T., 2012. The possibility of using the Landsat image archive for monitoring long time trends in coloured dissolved organic matter concentration in lake waters. Remote Sensing of Environment, 123, 334-338.Michelutti N., Blais J.M., Cumming B.F., Paterson A.M., Rühland K., Wolfe A.P., Smol J.P., 2010. Do spectrally inferred determinations of chlorophyll a reflect trends in lake trophic status?. Journal of Paleolimnology, 43(2), 205-217.Mobley C.D., 1999. Estimation of the remote-sensing reflectance from above-surface measurements. Applied Optics, 38(36), 7442-7455.Nhung P.T., Canh B.D., Ha N.T.T., Linh N.T., 2016. Modeling spatial-temporal distribution of total suspended solids concentrations in Day Estuary water using Landsat 8 Imagery. Proceeding of the 7th International Symposium Hanoi Geoengineering 2016 on Energy and Sustainability, Hanoi, October 21-22, 69-75.Olmanson L.G., Bauer M.E., Brezonik P.L., 2008. A 20-year Landsat water clarity census of Minnesota's 10,000 lakes. Remote Sensing of Environment, 112(11), 4086-4097.Padisák J., Borics G., Grigorszky I., Soroczki-Pinter E., 2006. Use of phytoplankton assemblages for monitoring ecological status of lakes within the Water Framework Directive: the assemblage index. Hydrobiologia, 553(1), 1-14.Palmer S.C., Kutser T., Hunter P.D., 2015. Remote sensing of inland waters: Challenges, progress and future directions. Remote Sens. of Environ. Special Issue: Remote Sensing of Inland Waters, 157(1), 1-8.Quang N.H., Sasaki J., Higa H., Huan N.H., 2017. Spatiotemporal Variation of Turbidity Based on Landsat 8 OLI in Cam Ranh Bay and Thuy Trieu Lagoon, Vietnam. Water, 9(8), 570.Son N.H., Anh B.T, Thuy N.T.T, 2000. Investigation of the Fisheries in Farmer-Managed Small Reservoir in Thai Nguyen and Yen Bai Province. Proceedings of an International Workshop on Reservoir and Culture-based Fisheries: Biology and Management. Bangkok, Thailand 15-18 February, 246-257.Tebbs E.J., Remedios J.J., Harper D.M., 2013. Remote sensing of chlorophyll-a as a measure of cyanobacterial biomass in Lake Bogoria, a hypertrophic, saline-alkaline, flamingo lake, using Landsat ETM+. Remote Sensing of Environment, 135, 92-106.Thuy D.B., Canh B.D., Ha N.T.T., Thao N.T.P., Nhi B.T., 2016. Modeling spatial distribution of total suspended solids concentration in Ha Long Bay water during the first quarter of 2016 using co-kriging interpolation and auxiliary data from Landsat 8 imagery. Proceeding of the 7th International Symposium Hanoi Geoengineering 2016 on Energy and Sustainability, Hanoi, October 21-22, 148-153.Tiwari S.P., Shanmugam P., Ahn Y.H., Ryu J.H., 2012. A Reflectance Model for Relatively Clear and Turbid Waters. Engineering, Technology Applied Science Research, 3(1), 325-337.UNEP, 2014. Review of existing water quality guidelines for freshwater ecosystems and application of water quality guidelines on basin level to protect ecosystems. Technical background document for theme 1: “Water Quality and Ecosystem Health”. First International Environment Forum for Basin Organizations towards Sustainable Freshwater Governance, 26-28 November 2014, Nairobi, Kenya.US Environmental Protection Agency, 2009. National lakes assessment: a collaborative survey of the nation's lakes, 103p.Vermote E., Justice C., Claverie M., Franch B., 2016. Preliminary analysis of the performance of the Landsat 8/OLI land surface reflectance product. Remote Sensing of Environment, 185, 46-56.Watanabe F., Alcantara E., Rodrigues T., Rotta L., Bernardo N., Imai N., 2018. Remote sensing of the chlorophyll-a based on OLI/Landsat-8 and MSI/Sentinel-2A (Barra Bonita reservoir, Brazil). Anais da Academia Brasileira de Ciências, 90(2), 1987-2000.Yang Z., Anderson Y., 2016. Estimating chlorophyll-a concentration in a freshwater lake using Landsat 8 Imagery. J. Environ. Earth Sci., 6(4), 134-142
A STUDY ON BREAKDOWN PROPERTIES OF COCONUT OIL
Get PDFThis paper presents the results of electric breakdown properties of coconut oil with AC voltage. Experimental results show that breakdown voltage of new coconut oil is comparable to that of mineral oil. Ageing was seen to significantly affect the breakdown voltage of both coconut oil and mineral oil. However, influence extent of ageing on the breakdown voltage was higher for mineral oil. The antioxidant was seen to reduce the breakdown voltage of new coconut oil, but raised the breakdown voltage of aged coconut oil. The V-t characteristic of coconut oil is not as good as that of mineral oil
Screening genes encoding protein protease inhibitor from metagenome of sponge-associated microorganisms in Quang Tri sea, Vietnam
Get PDFUsing metagenomics-based method to isolate new compounds from the marine environment are getting more and more attention in recent years. Based on metagenome library, bioinformatics methods is a powerful tool for screening genes with new biological activities from uncultured microorganisms and become a breakthrough in research and application of biotechnology. In this study we selected and used the samples DNA QT2 which had high DNA content and purity from a total of 6 DNA samples of sponge-associated microorganisms collected in Quang Tri sea (Vietnam) for metagenomic sequencing (DNA concentration is 202.5 ng, A260/ A280 value is 1.80). 16S rRNA metagenomic sequencing data of QT2 produced 44,117,722 reads, which were assembled into 120,236 contigs. ORF prediction using Prodigal produced 386,416 ORFs. Functional annotation was conducted based on 7 different databases (NR, COG, CAZy, Swissprot, GO, KEGG, Pfam), and there are 266,553 genes were annotated using Swiss-Prot. In addition, based on the obtained metagenomic data, 50 complete genes encoding protease inhibitor proteins were revealed and among them, 28 genes encoding protein ( 50%) belonged to the serine protease inhibitor family, and 22 genes genes encoding belonged to the Inter-alpha-trypsin inhibitor group. NCBI BLAST screening results that these proteins had higher 50% identity to protease inhibitors.
Mining cytochrome p450 genes through next generation sequencing and metagenomic analysis from Binh Chau hot spring
Get PDFCytochrome P450s (CYPs) are one of the largest distributed enzymes, which catalyze more than 20 different reactions. At present, there has been an increasing realization of the power of P450 biocatalysts for the industrial synthesis of pharmaceuticals, agrochemicals, bulk chemicals, food ingredients, etc. On the other hand, the conditions of industrial processes at high temperature, high-pressure or in chemical solvent require the enzymes, which catalyze the bioconversion, have a specific properties such as thermostability, chemical tolerance or barophilicity. Up to date, the number of thermostable P450s is limited. Nowadays, DNA-metagenome technique gives us a chance to catch novel genes and unique interesting enzymes from microbial community in certain ecology. In this paper, metagenomic DNA extracted from water samples from Binh Chau hot spring was sequenced using Illumila’s HiSeq platform and was analysed to mining putative genes encoding cytochrome P450. The sequencing generated 9.4 Gb of reads containing 156,093 putative ORFs, of these, 106,903 genes were annotated in NCBI non-redundant protein sequence database. Among all the ORFs were annotated, 68 putative ORFs encoding cytochrome P450 were found belong to 36 specific groups of cytochrome P450 protein family. Of these, the melting temperature (Tm) from thirty-six completed ORFs was predicted for a better understanding of thermodynamic stability.
The tonkin snub-nosed monkey Rhinopithecus avunculus population in the Quan Ba forest, north-east Vietnam: an identification of priority habitat for conservation
Get PDFThe Tonkin Snub-nosed Monkey Rhinopithecus avunculus is among the World’s 25 most endangered primates. At present, the species is found only in few forest areas in Ha Giang and Tuyen Quang Provinces, north-east Vietnam with a total number not exceeding 250 individuals. The forest block in Cao Ma Po, Ta Van and Tung Vai Communes of Quan Ba District, Ha Giang Province (the Cao - Ta - Tung forest) harbors the second largest population of Tonkin Snub-nosed Monkey. This population was estimated to be conisted of about 30–35 individuals in 2007. However, it faces a number of serious threats (wildlife hunting, habitat degradation by widespread forest farming of Tsao-ko cardamom plant, etc.) that may lead the population to be extinct in near future. The population was reduced to 15–21 individuals in 2016 due to these threats. In 2017–2018, we conducted a study to identify a priority habitat area to establish the Quan Ba Tonkin Snub-nosed Monkey Conservation Area. The results of our study show that the distribution of the Quan Ba Tonkin Snub-nosed Monkey population is confined to a small area (about 5,000 ha) belonging to the Theng Chu Phin, Dao Dan Chai, Ta Lay mountains, the Hill 754 and a forest patch along the Vietnam-China border from the Post 283 to Post 295. This area harbors the best forest of the Cao - Ta - Tung area. The forest covers 92.3% of the area, and only 7.7% of the area is a non-forest land. There are two types of forest: evergreen broad-leaved forest (50.0% of total area) and limestone evergreen broad-leaved forest (42.3%). The evergreen broad-leaved forest has been degraded to medium and restoration status. Tsao-ko cardamom Amomum tsao-ko fields are widespread. The limestone evergreen broad-leaved forest of almost primary status remains in very steep slopes and limestone mountains. The Cao - Ta - Tung forest was designated as a watershed protection forest that allows farming of agricultural and medicinal plants inside the forest and the forest farming of Tsao-ko cardamom is widespread becoming the most serious threat to the long-term survival of the Tonkin Snub-nosed Monkey population. In order to ensure long-term survival of the Quan Ba Tonkin Snub-nosed Monkey population, the area of the Theng Chu Pin, Dao Dai Chai, Ta Lay, Tung Lau mountains, the Hill 754 and a forest patch along the Vietnam-China border from the Post 283 to Post 285 must be designated as a special-use forest, i.e. to establish a Quan Ba Tonkin Snub-nosed Monkey Conservation Area.
Effects of seeds treated with cobalt nanoparticles on germination, growth, yield and quality of soybean cultivar DT12
Get PDFSeed treatment using metallic nanoparticles to stimulate germination and improve crop yields has been published and widely applied in agriculture production. To assess the safety of such methods on plants, the effectiveness and safety of the treatment of soybean Glycine max L. DT12 seeds with cobalt nanoparticles (nCo) before sowing were investigated. Seeds of soybean cultivar DT12 were treated with nCo at two different concentrations (0.165 and 1.65 mg/kg seed) before sowing. Germination rate, growth speed, soybean yield and bean nutrient components were examined throughout a season. Results implied that at a concentration of 0.165 mg/kg, nCo significantly increased germination rates, plant heights, total pods per plant, number of pods having 3 seeds, and crop productivity compared to both the control and seeds treated with a highter concentration of 16.5 mg per kg of seed. However, no significant differences were found between treatments in terms of growth level and seed nutrient contents, including moisture, ash content, mineral (K, Mg and Fe) and crude protein components. In seeds treated with higher concentration, the Ca content was dramatically lower than that of the control and seeds treated with a low concentration, but bean quality was not affected. This study contributes to the effective and sustainable application of nanomaterials in Vietnamese agriculture.
