Vietnam Academy of Science and Technology: Journals Online
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HUPSMT: AN EFFICIENT ALGORITHM FOR MINING HIGH UTILITY-PROBABILITY SEQUENCES IN UNCERTAIN DATABASES WITH MULTIPLE MINIMUM UTILITY THRESHOLDS
Get PDFThe problem of high utility sequence mining (HUSM) in quantitative se-quence databases (QSDBs) is more general than that of frequent sequence mining in se-quence databases. An important limitation of HUSM is that a user-predened minimum tility threshold is used commonly to decide if a sequence is high utility. However, this is not convincing in many real-life applications as sequences may have diferent importance. Another limitation of HUSM is that data in QSDBs are assumed to be precise. But in the real world, collected data such as by sensor maybe uncertain. Thus, this paper proposes a framework for mining high utility-probability sequences (HUPSs) in uncertain QSDBs (UQS-DBs) with multiple minimum utility thresholds using a minimum utility. Two new width and depth pruning strategies are also introduced to early eliminate low utility or low probability sequences as well as their extensions, and to reduce sets of candidate items for extensions during the mining process. Based on these strategies, a novel ecient algorithm named HUPSMT is designed for discovering HUPSs. Finally, an experimental study conducted in both real-life and synthetic UQSDBs shows the performance of HUPSMT in terms of time and memory consumption
Estimation of Curie point depths in the Southern Vietnam continental shelf using magnetic data
No full textThis study attempts to estimate the thermal structure in the Southern Vietnam continental shelf by calculating the Curie point depth isotherm using magnetic data. The Curie point depth values, from 49 overlapping blocks 128 × 128 km in size, have been estimated by the exponential approach. This approach is based on the analytical solution of the exponential equations obtained from transforming the magnetic anomaly data into the frequency domain. According to the obtained results, the range of Curie point depths is from 15.3 to 35.6 km. In the study area, the greatest Curie point depth is located in the South-Eastern part, and the smallest depth is located at North-Western part. The heat flows derived from the Curie point depths are also presented. The obtained results are at relatively high resolutions and in agreement with the published information available for the study area. The Curie point depths generally lie below the Moho surface in this region but lie above in some locations, notably the Cuu Long basin
Formation pressure - temperature (P-T) of Ye Yen Sun granite
No full textYe Yen Sun Cenozoic granitoid formations include biotite granite, fine- to medium-grained amphibol-biotite granite, and mostly undeformed fine- grained granite porphyry. Temperature calculation by the zircon saturation method gives the formation temperature ranging from about 680°C to 850°C; the pressure, determined on the basis of the major element composition, varies between 10 and 1 kbar (about 33 to 3.3 km deep). The granites viewed as "hot" or "intermediate" magmas were formed at the site of extension or transformation tectonics. Thus, the ability to form these granites due to the melting of the lower crust under the stretching region along the two wings of the Red River shear zone is a mechanism to be considered
Controllable Optical Properties of Multiple Electromagnetically Induced Transparency in Gaseous Atomic Media
Get PDFThe advent of electromagnetically induced transparency (EIT) offered a new coherent material with exotic and controllable optical properties. Although, studies on single-EIT are described in detail for single-EIT, however, extension from single- to multi- EIT is currently of current interest due to it gains advantages in multi-channel optical communication, waveguides for optical signal processing and multi-channel quantum information processing. In this work, we review recent research works concerning multi-EIT and some related applications, as controlling group velocity of light, giant Kerr nonlinearity, optical bistability. A special attention of the review also gives for analytical interpretations of EIT spectrum, its dispersion and related applications such as EIT enhanced Kerr nonlinearity and optical bistability to give physics insight. From experimental point of view, a latest development for measuring multi-EIT spectrum and its dispersion in hot medium is presented and compared to theoretical analytical representations
Study of Oxygen Vacancy Diffusion in Yttria-doped Ceria and Yttria-stabilized Zirconia by Statistical Moment Method
Get PDFOxygen vacancy diffusion in yttria-doped ceria (YDC) and yttria-stabilized zirconia(YSZ) are investigated using statistical moment method, including the anharmonicity effects of thermal lattice vibrations. The expressions of oxygen vacancy-dopant association energy and oxygen vacancy migration energy are derived in an explicit form. Calculation of the vacancy migration energy enable us to evaluate the important role of dopant cation on the oxygen vacancydiffusion. The dependences of the vacancy activation energies and diffusion coefficients in YDC and YSZ systems on dopant concentration are also discussed in detail. The calculated results are in good agreement with the other theoretical and experimental results
Characterization of High-power DFB-MOPA Diode Lasers Emitting at 1064 nm
Get PDFDetail characterization of the such laser diode is important for the applications. Electro-Optical and spectral characteristics of the high power 1064 nm DFB-MOPA lasers are investigated at room temperature as function of injection current. Beam quality is characterized by waist diameter and far-field divergence angle versus average optical output power. Beam propagation ratio M2 is defined at difference intensity levels from lateral beam profile giving more detail laser behaviors at high power
THAY ĐỔI ĐƯỜNG BỜ BIỂN TRÀ VINH TỪ NĂM 1989 – 2014
No full textThe coastline of Tra Vinh, about 65 km long from the mouth of Cung Hau to Dinh An, is composed of loose sediment, which is easily affected by natural factors and human activities. Based on satellite image analysis combined with survey and field measurements, the changes in coastline between 1966 and 2014 were identified. The results show that in this period the coastline had an average deposition rate of about 5–10 m/year. Dong Hai was the strongest deposition area with maximum rate of 40 m/year, average 28–30 m/year. The eroded coastline alternated with an average erosion rate of about 5–8 m/year. From 1990 up to now, many human constructions have been carried out along the coast of Tra Vinh, contributing to the impact of changing the shoreline. In the area of My Long Nam, Dong Hai and Long Vinh, the mangrove planting project was performed which helped to create continuous accretion of coastline with average rate of 17–33 m/year. In the period of 2009–2014, sea dykes in Hiep Thanh commune and Con Truong, Truong Long Hoa commune were built to prevent coastal erosion. During 2009–2014, Hiep Thanh coast and Truong Long Hoa coast were eroded at an average rate of 8–20 m/year and 6–10 m/year, respectively. After appearance of the dykes, the survey results show that in the 2014–2015 period, the shoreline of Hiep Thanh and Con Trung which has sea dykes was no longer eroded, but the adjacent coastline was more eroded at an average rate of 14–38 m/year. In Dan Thanh commune, where Duyen Hai electric center and Quan Chanh Bo canal were constructed, from 2009 to 2014, the coastline was eroded with the average rate of 12–24 m/year. In 2014–2015 period, coastal erosion was stronger at an average rate of 36–45 m/year.Nằm ở vị trí ven biển ở đồng bằng sông Cửu Long (ĐBSCL) Trà Vinh có đường bờ biển tự nhiên dài 65 km hình cánh cung kéo dài theo hướng đông bắc - tây nam, giữa2sônglớnlàsôngHậuvàCổ Chiên. Trong vòng 25 năm qua, bờ biển Trà Vinh luôn thay đổi, quá trình bồi tụ và xói lở xen kẽ nhau, khu vực xã Mỹ Long Nam, Long Vĩnh, đặc biệt đoạn bờ xã Đông Hải là nơi bồi tụ nhiều nhất khu vực ven biển. Tuy nhiên, những năm gần đây đường bờ biển có xu hướng xói lở, khu vực xói lở mạnh là đoạn bờ xã Hiệp Thạnh, Trường Long Hòa và Dân Thành, nhưng nhìn chung đường bờ trong vòng 25 năm xu hướng bồi tụ vẫn chiếm ưu thế
TERPENOIDS FROM THE LEAVES AND STEMS OF DYSOXYLUM TPONGENSE
Get PDFStudy on chemical constituents from the leaves and stems of Dysoxylum tpongense Pierre resulted in the isolation of six known compounds (1–6). The chemical structures of isolated compounds were identified as cabraleahydroxylactone (1), cabraleahydroxylactone-3-acetate (2), (+) spathulenol (3), b-sitosterol (4), stigmasterol (5), and stigmast-4-en-3-one (6) by comparison of the physicochemical, interpretation of NMR and mass spectral data with that reported in the literature
A CIPHERTEXT-POLICY ATTRIBUTE-BASED SEARCHABLE ENCRYPTION SCHEME IN NON-INTERACTIVE MODEL
Get PDFWe address the problem of searching on encrypted data with expressive searching predicate and multi-writer/multi-reader, a cryptographic primitive which has many concrete application scenarios such as cloud computing, email gateway application and so on. In this paper, we propose a public-key encryption with keyword search scheme relied on the ciphertext-policy attribute-based encryption scheme. In our system, we consider the model where a user can generate trapdoors by himself/herself, we thus can remove the Trusted Trapdoor Generator which can save the resource and communication overhead. We also investigate the problem of combination of a public key encryption used to encrypt data and a public-key encryption with keyword search used to encrypt keywords, which can save the storage of the whole syste
Investigation of AA5083 T-lap joint fabricated by friction stir welding
Get PDFTransportation industries are faced to big maters that the scientists focus on, such as energy saving and ecologically sustainable products. Therefore, many innovative solutions are delivered that will support environmental preservation but meet industries’ requirements for greater productivity and minimized operational costs. Aluminium alloys have successfully contributed to meeting the rising demand for lightweight structures. Recently, notable developments in aluminium welding techniques have resolved many welding related problems, although some problems need to be addressed. In this paper, 5083 aluminium alloy T-lap-joints were successfully fabricated by friction stir welding with various welding regimes. The defects morphology in the T-joints was experimentally observed and analyzed by a high magnification microscope. The roles of the grain microstructure and the effects of defects morphology in the mechanical behavior of the T-joint was investigated. In addition, the fracture locations and the fracture surface of the failure specimens were observed and discussed as well. Results indicate that the fracture of T-joints along the stringer is attributed to the bonding line defects, kissing bond defects and the tunnel defects. The result also shows, in the T-joints of 5083 aluminum alloy, the welding parameters influence significantly on the features and sizes of the defects