Vietnam Academy of Science and Technology: Journals Online
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ĐẶC ĐIỂM PHÂN BỐ CỦA LOÀI SÚT (ANOMALODISCUS SQUAMOSUS) Ở THỦY VỰC NHA PHU, TỈNH KHÁNH HÒA
No full textDistribution and resource characteristics of the clam Anomalodiscus squamosus in Nha Phu, Khanh Hoa province was studied by two surveys carried out in 2016–2017. The results have shown that, Anomalodiscus Squamosus was a good sources of income (804 tons/year and over 4.1 billion VND) for the communities living around the estuary of Nha Phu. Exploited yield of Anomalodiscus squamosus of dry season bigger than that in the rainy season (67% of total yield catches in both seasons). Anomalodiscus squamosus distributed in areas with temperature and salinity ranges from 29–31oC and 25–27‰, respectivelyand distributed along with other bivalves such as Gari elongata (Lamarck, 1818), Anadara nodifera (Martens, 1860), Anadara antiquata (Linnaeus, 1758) and were also affected by sandy sediments and mangroves, mainly sandy sediments. The results of this study provide a scientific basis for the proposed solutions for restoration, conservation and rational exploitation of Anomalodiscus squamosus.Đặc điểm phân bố của loài sút (Anomalodiscus Squamosus) ở thủy vực Nha Phu, tỉnh Khánh Hòa được xác định thông qua 2 chuyến điều tra khảo sát vào mùa mưa và mùa khô năm 2016 – 2017. Kết quả nghiên cứu cho thấy, Sút (Anomalodiscus Squamosus) là loài nguồn lợi mang lại doanh thu cao (804 tấn/năm và trên 4,1 tỷ đồng) cho cộng đồng dân cư sống quanh thủy vực Nha phu. Sản lượng khai thác Sút vào mùa khô chiếm ưu thế so với mùa mưa (chiếm 67% trên tổng sản lượng khai thác của cả hai mùa). Sút phân bố ở những khu vực có nhiệt độ và độ muối dao động từ 29 – 31oC và 25 – 27 ‰ và phân bố cùng với các loài Hai mảnh vỏ khác như Gari elongata (Lamarck, 1818), Anadara nodifera (Martens, 1860) và Anadara antiquata (Linnaeus, 1758) và cùng chịu sự chi phối của trầm tích đáy cát và RNM, trong đó chủ yếu là trầm tích đáy cát. Kết quả nghiên cứu này cung cấp cơ sở khoa học cho việc đề xuất các giải pháp phục hồi, bảo tồn và khai thác hợp lý nguồn lợi Sút
USING THE COMBINATION OF THE 3D GRAVITY INVERSION METHOD WITH THE DIRECTIONAL ANALYTIC SIGNAL DERIVATIVES AND THE CURVATURE GRAVITY GRADIENT TENSOR METHOD TO DETERMINE STRUCTURE OF THE PRE-CENOZOIC BASEMENT ON SOUTHEAST CONTINENTAL SHELF OF VIETNAM
No full textIn this paper, we present some new results of the Pre-Cenozoic basement structure on the Southeast continental shelf of Vietnam based on the combination of some modern methods to analyse and interpret gravity data. They are the 3D gravity inversion method, the directional analytic signal derivatives and the curvature gravity gradient tensor. The results obtained include the density distribution, the fault system and the main structural blocks inside of the Pre-Cenozoic basement on Southeast continental shelf of Vietnam. The initial results about density distribution show that it relatively clearly reflects the shape of basins in the area: The contours that have value σ =2.7 g/cm3 and value σ = 2.76 g/cm3 are near the edges of the Cuu Long basin and the Nam Con Son basin, respectively. The density value reaches the maximum at the center of basins. For the Cuu Long basin, the maximum value is σmax= 2.76 g/cm3 and the Nam Con Son has maximum value σmax= 3.0 g/cm3. Many faults that appear in the study area have the existence depth in the wide range from 6 km to 30 km, even above 30 km and the faults that have the existence depth from 8 to 10 km are in the majority. In particular, the boundary of anomalous sources existing in the Pre-Cenozoic basement is shown by the better resolution, at which more edge points are identified than the maximum horizontal gradient amplitude method that is widely used. The results also show that the combination of individual results complements each other and creats the sufficient and clearer picture inside of the Pre-Cenozoic basement
THỬ NGHIỆM ĐỒNG HOÁ SỐ LIỆU ĐỘ CAO SÓNG TRONG KHU VỰC BIỂN ĐÔNG BẰNG PHƯƠNG PHÁP LỌC KALMAN TỔ HỢP
No full textAdvances in ocean data assimilation have been improved with the power of computers over the past 30 years, but the theory of data assimilation has a long history with the probability, theory of mathematical simulation, and traditional numerical calculations. Therefore, the research and application of data assimilation technology in oceanography have been widely carried out in the world and have gotten considerable achievements. In Vietnam, the study of data assimilation has also been applied in the meteorology and has attracted the increasing interest in oceanography. This paper presents the results of the study to calculate the wave height data from satellites combined with measured wave height data at MSP1 station of Vietsovpetro using the Ensemble Kalman Filter (EnKF) method associated with SWAN wave model in the Eastern Vietnam Sea.Các tiến bộ trong phương pháp đồng hóa số liệu đại dương ngày càng phổ biến với năng lực của máy tính được nâng cao trong 30 năm trở lại đây, nhưng lý thuyết về đồng hóa số liệu đã có lịch sử lâu dài với nền tảng toán học về xác suất, lý thuyết mô phỏng và các tính toán truyền thống về biến thiên số. Chính vì vậy, việc nghiên cứu và ứng dụng công nghệ đồng hoá số liệu trong hải dương học đã được áp dụng rộng rãi ở nhiều nơi trên thế giới và đạt được những thành tựu đáng kể. Ở Việt Nam, việc nghiên cứu đồng hoá số liệu cũng đã được áp dụng nhiều trong ngành khí tượng và dần được quan tâm trong hải dương học. Bài báo này trình bày kết quả nghiên cứu thử nghiệm đồng hoá số liệu độ cao sóng từ vệ tinh kết hợp với số liệu độ cao sóng đo đạc tại trạm MSP1 của VietSo Petro bằng phương pháp lọc Kalman tổ hợp (EnKF) cho mô hình sóng SWAN phục vụ tính toán sóng trong khu vực Biển Đông
A Feature-Based Model for Nested Named-Entity Recognition at VLSP-2018 NER Evaluation Campaign
Get PDFIn this report, we describe our participant named-entity recognition system at VLSP 2018 evaluation campaign. We formalized the task as a sequence labeling problem using BIO encoding scheme. We applied a feature-based model which combines word, word-shape features, Brown-cluster-based features, and word-embedding-based features. We compare several methods to deal with nested entities in the dataset. We showed that combining tags of entities at all levels for training a sequence labeling model (joint-tag model) improved the accuracy of nested named-entity recognition
CHEMICAL CONSTITUENTS FROM THE LEAVES OF Uvaria boniana Fin. & Gagnep IN VIETNAM
No full textAbstract HCTN_12A phytochemical study of extracts of Uvaria boniana Fin. Gagnep collected at Vũ Quang National park, Nghe An province leaves led to the isolation of five secondary metabolites, including uvaridacol G (1); 4-methyl-4-[(2Z)-3’-phenylprop-2’-en-1’-yl]cyclohex-2-en-1-one (2); 3,7- dimethoxy quercetin 4’- O- [α-L- rhamnopyranosyl-(12) -β-D- glucopyranoside (3); b-sitosterol (4) and stigmasterol (5). Their structure elucidation were determined on the basis of one and two-dimensional NMR and spectrometric methods in combination with molecular modeling. This is the first report on the chemical constituents of Vietnamese Uvaria boniana
A DISTANCE BASED INCREMENTAL FILTER-WRAPPER ALGORITHM FOR FINDING REDUCT IN INCOMPLETE DECISION TABLES
Get PDFTolerance rough set model is an effective tool for attribute reduction in incomplete decision tables. In recent years, some incremental algorithms have been proposed to find reduct of dynamic incomplete decision tables in order to reduce computation time. However, they are classical filter algorithms, in which the classification accuracy of decision tables is computed after obtaining reduct. Therefore, the obtained reducts of these algorithms are not optimal on cardinality of reduct and classification accuracy. In this paper, we propose the incremental filter-wrapper algorithm IDS_IFW_AO to find one reduct of an incomplete desision table in case of adding multiple objects. The experimental results on some sample datasets show that the proposed filter-wrapper algorithm IDS_IFW_AO is more effective than the filter algorithm IARM-I [17] on classification accuracy and cardinality of reduc
CONTRIBUTE TO STUDY ON CHEMICAL CONSTITUENTS OF DESMODIUM GANGETICUM (L.) DC. OF VIETNAM
No full textFrom the ethyl acetate extract of the leaves of Desmodium gangeticum collected in Me Linh, Ha Noi, we isolated 5 compounds including luteolin (1), luteolin tetramethyl ether (2), N,N-dimethyl tetradecane-1-amin (3), D-pinitol (4) and stigmasterol (5). In which, luteolin (1) was isolated from Desmodium gangeticum for the first time, luteolin tetramethyl ether (2) and N,N-dimethyl tetradecane-1-amin (3) were first isolated from genus Desmodium. Their structures were determined by 1D and 2D NMR spectra
Seismogenic nodes as a viable alternative to seismogenic zones and observed seismicity for the definition of seismic hazard at regional scale
No full textA fixed increment of magnitude is equivalent to multiply the seismic moment by a factor γEM related to the partial factor γq acting on the seismic moment representing the fault. A comparison is made between the hazard maps obtained with the Neo-Deterministic Seismic Hazard Assessment (NDSHA), using two different approaches: one based on the events magnitude, listed in parametric earthquake catalogues compiled for the study areas, with sources located within the seismogenic zones; the other uses the seismogenic nodes identified by means of pattern recognition techniques applied to morphostructural zonation (MSZ), and increases the reference magnitude by a constant amount tuned by the safety factor γEM.Using γEM=2.0, in most of the territory the two approaches produce totally independent, comparable hazard maps, based on the quite long Italian catalogue. This represents a validation of the seismogenic nodes method and a tuning of the safety factor γEM at about 2
Developing land-cover driver model for estimating the intensity of surface urban heat islands using landsat 8 satellite imagery
No full textIt is of utmost importance to understand and monitor the impact of urban heat islands on ecosystems and overall human health in the context of climate change and global warming. This research was conducted in a tropical city, Hanoi, with a major objective of assessing the quantitative relationships between the composition of the main land-cover types and surface urban heat island phenomenon. In this research, we analyzed the correlation between land-cover composition, percentage coverage of the land cover types, and land surface temperature for different moving window sizes or urban land management units. Landsat 8 OLI (Operational Land Imager) satellite data was utilized for preparing land-cover composition datasets in inner Hanoi by employing the unsupervised image clustering method. High-resolution (30m) land surface temperature maps were generated for different days of the years 2016 and 2017 using Landsat 8 TIRS (Thermal Infrared Sensor) images. High correlations were observed between percentage coverage of the land-cover types and land surface temperature considering different window sizes. A new model for estimating the intensity of surface urban heat islands from Landsat 8 imagery is developed, through recursively analyzing the correlation between land-cover composition and land surface temperature at different moving window sizes. This land-cover composition-driven model could predict land surface temperature efficiently not only in the case of different window sizes but also on different days. The newly developed model in this research provides a wonderful opportunity for urban planners and designers to take measures for adjusting land surface temperature and the associated effects of surface urban heat islands by managing the land cover composition and percentage coverage of the individual land-cover types
Provitamin a biofortification in maize through genetic engineering and marker-assisted selection
Get PDFMaize is an important cereal in the global economy, which feeds one-third of the world’s population and is the third largest food crop after wheat and rice. Nutritional quality of most maize varieties is very low due to the lack of lysine and tryptophan and extremely low provitamin A carotenoids including α-carotene, β-carotene, and β-cryptoxanthin. Therefore, one of the solutions to improve nutritional value in maize is to improve provitamin A carotenoids contents. Many efforts have been made to produce maize plants with enhanced provitamin A carotenoids, especially, β -carotene. This article aims to review the research towards provitamin A biofortification through genetic engineering and marker-assisted selection. The published results and our recent achievements open the window for the improvement of provitamin A carotenoids in maize as well as the issues that need the further investigation.