Disturbance observer-based controller for inverted pendulum with uncertainties: Linear matrix inequality approach

A new approach based on linear matrix inequality (LMI) technique for stabilizing the inverted pendulum is developed in this article. The unknown states are estimated as well as the system is stabilized simultaneously by employing the observer-based controller. In addition, the impacts of the uncertainties are taken into consideration in this paper. Unlike the previous studies, the uncertainties in this study are unnecessary to satisfy the bounded constraints. These uncertainties will be converted into the unknown input disturbances, and then a disturbance observer-based controller will be synthesized to estimate the information of the unknown states, eliminate completely the effects of the uncertainties, and stabilize inverted pendulum system. With the support of lyapunov methodology, the conditions for constructing the observer and controller under the framework of linear matrix inequalities (LMIs) are derived in main theorems. Finally, the simulations for system with and without uncertainties are exhibited to show the merit and effectiveness of the proposed methods

Incidence of dengue and chikungunya viruses in mosquitoes and human patients in border provinces of Vietnam

Background: Dengue virus remains a major threat in Vietnam, while chikungunya virus is expected to become one. Surveillance was conducted from 2012 to 2014 in Vietnam to assess the presence of dengue and chikungunya viruses in patients hospitalized with acute fever in five Vietnam provinces neighboring Lao PDR and Cambodia. Surveillance was extended to mosquitoes present in the vicinity of the patients' households. Results: A total 558 human serum samples were collected along with 1104 adult mosquitoes and 12,041 larvae from 2250 households. Dengue virus was found in 17 (3%) human serum samples and in 9 (0.8%) adult mosquitoes. Chikungunya virus was detected in 2 adult mosquitoes (0.18%) while no chikungunya virus was detected in humans. Differing densities of mosquito populations were found, with the highest in the Long An Province border with Cambodia. Long An Province also displayed the lowest rate of infection, despite a very high Breteau Index, high human population density and presence of the main cross border road system. The highest incidence was found in Dac Nong Province, where the Breteau and Container indices were the second lowest. Dengue virus was detected in five Aedes albopictus, three Aedes aegypti and one Culex vishnui. Chikungunya virus was detected in two Ae. aegypti. All infected mosquitoes belonged to haplotypes described in other parts of the world and a number of novel haplotypes were found among uninfected mosquitoes. Conclusions: Dengue is considered to be regularly introduced to Vietnam from Cambodia, mostly through human movement. The data reported here provides a complementary picture. Due to intensive international trade, long-distance transportation of mosquito populations may play a role in the regular importation of dengue in Vietnam through Ho Chi Minh City. It is important to decipher the movement of mosquitoes in Vietnam, not only at the Lao PDR and Cambodia borders but also through international trade routes. Mosquito surveillance programs should address and follow mosquito populations instead of mosquito species

Validation of Mesocyclops (Copepoda) and community participation as an effective combination for Dengue control in Northern Vietnam

The “Programme Meso-Vietnam” was implemented in Vietnam from October 2007 to December 2010 to reduce dengue and dengue hemorrhagic fever incidence and to improve the quality of life in the four project communes. This dengue control project was based on biological control using Mesocyclops, a larvivorous micro-crustacean, as well as on the establishment of a strong community involvement to educate the population on dengue transmission and to reduce Aedes breeding by removal of containers. During three years, a network of collaborators was responsible for introducing Mesocyclops in all the containers defined as key breeding-sites, and regular activities such as community training workshops, school programmes, clean-up campaigns and health promotion through IEC programmess were performed. To make this programme sustainable, local leadership has been strengthened as well. The use of these larvivorous micro-crustaceans as a biological control strategy against dengue over the medium and long term, when combined with community participation and effective health promotion, demonstrated a significant reduction in dengue vector populations and dengue cases.  In Vietnam, this study reconfirms that there is an ecological alternative to systematic use of insecticides to control dengue vector population. (Abstract word count: 186)Le " Programme Meso-Vietnam " a été mis en œuvre au Vietnam entre octobre 2007 et décembre 2010. Ce programme vise à réduire l'incidence de la dengue et de la fièvre hémorragique de la dengue et à améliorer la qualité de vie dans les quatre communes sélectionnées pour le projet. Ce projet de lutte contre la dengue était basé sur un contrôle biologique assuré par des Mésocyclopes, micro-crustacés larvivores, et sur l'établissement d'une forte implication de la communauté pour éduquer la population sur la transmission de la dengue et pour réduire la reproduction des moustiques Aedes par élimination des conteneurs leur servant de site de ponte. Pendant trois ans, un réseau de collaborateurs a été chargé d'introduire des Mésocyclopes dans tous les conteneurs définis comme des sites de reproduction clés, et des activités régulières telles que des ateliers de formation communautaires, des programmes scolaires, des campagnes de nettoyage et des activités de promotion de la santé via les programmes IEC ont été mises en place. En outre, pour assurer la pérennité de ce programme, le leadership local a été renforcé. L'utilisation de ces micro-crustacés larvivores comme stratégie de contrôle biologique de la dengue à moyen et long terme, associée à une participation communautaire et à une promotion efficace de la santé, a permis d'aboutir à une réduction significative des populations vecteurs de la dengue et des cas de dengue. Au Vietnam, cette étude confirme une fois de plus qu'il existe une alternative écologique à l'utilisation systématique d'insecticides pour lutter contre les vecteurs de la dengue.El “Programa Meso-Vietnam” se implementó en Vietnam desde octubre de 2007 hasta diciembre de 2010 para reducir la incidencia del dengue y la fiebre hemorrágica del dengue y para mejorar la calidad de vida en los cuatro municipios del proyecto. Este proyecto de control del dengue se basaba en el control biológico usando Mesocyclops, un microcrustáceo larvívoro, así como en el establecimiento de una fuerte implicación comunitaria para educar a la población sobre la transmisión del dengue y para reducir la cría de Aedes mediante la eliminación de recipientes. Durante tres años, una red de colaboradores fue responsable de la introducción de Mesocyclops en todos los recipientes definidos como sitios clave para la cría, y se realizaron actividades regulares tales como talleres de formación comunitaria, programas escolares, campañas de limpieza y promoción de la salud a través de programas de IEC. Para hacer sostenible este programa, también se reforzó el liderazgo local. El uso de estos microcrustáceos larvívoros como estrategia de control biológico contra el dengue a medio y largo plazo demostró una reducción significativa de las poblaciones de vectores del dengue y los casos de dengue cuando se combinaba con la participación comunitaria y la promoción eficaz de la salud. En Vietnam, este estudio vuelve a confirmar que existe una alternativa ecológica al uso sistemático de insecticidas para controlar la población de vectores del dengue

GENETIC DIVERSITY IN THE NATURAL POPULARIONS OF Pinus dalatensis Ferre’ (PINACEAE) ASSESSED BY SSSR MARKERS

Pinus dalatensis Ferre’(Family: Pinaceae) is an endemic plant with restricted habitats at higher altitudes in Vietnam highland. The species are now near threatened by over-exploitation and habitat destruction. The genetic variation within and among populations of P. dalatensis was investigated by 41 microsatellite (single sequence repeat, SSR) primers, but only 11 SSR primers showed polymorphism bands. In all, 70 sampled trees from six populations in Vietnam highland were analyzed in this study, samples were collected from populations located in different altitude. A total of 40 allelic variants have been detected. The mean number of alleles per locus was 2.197. The SSR data showed a genetic diversity parameters within populations with an average of I = 0.524, Ho = 0.222, He = 0.317, Fis =0.333 and Ap = 0.106. The number private alleles (Ap) was only found in four populations, the Hoa Son population showed the highest (0.273), followed by Da Chay (0.182), and value of 0.091 for all Ngoc Linh and A Yun. Analysis of molecular variance analysis showed that most genetic variation was within populations of 57.504 % and among population of 42.496 %. The population pairwise differentiations indicated that most of the populations were significantly differentiated p 0.001 with Fst values ranged from 0.195 to 0.418. This study highlights the importance of conserving the genetic resources of P. dalatensis specie

ASSESSMENT OF GEOMORPHIC PROCESSES AND ACTIVE TECTONICS IN CON VOI MOUNTAIN RANGE AREA (NORTHERN VIETNAM) USING THE HYPSOMETRIC CURVE ANALYSIS METHOD

the Day Nui Con Voi (DNCV) area of Vietnam. For this purpose, a spatial database was collected and constructed, including DEM (Digital Elevation Model) and a geological map. The hypsometric curve (HC) analysis method and its statistical moments were adopted to use for the assessment. These methods have been widely used for the assessment of geomorphic processes and active tectonics in many areas in the world showing promising results. A total of 44 sub-basins of the Red River and the Chay river were analyzed. The result shows that 3 curve-types such as "straight- shape", "S- shape", and concave were found; with the concave curve being the dominant and widely distributed in the northeast side and in the south of the southwestern side of the study area. The hypsometric integral (HI) values are rather small with the largest value is 0.37 and the smallest one is 0.128. Other statistical moments of the hypsometric curve, i.e. skew (SK), kurtosis (KUR), and the density function (density skew - DSK and density kurtosis-DKUR) show great values, which increased in the south direction of the area study. Accordingly, recent active tectonics (uplift-lower) in the study area is generally weak; however, they are also not completely homogeneous and can be distinguished by different levels. The southwestern side is being lifted higher than the northeastern side. The northern part is being lifted larger than the southern part. In the region, the uplift activities were increased gradually in the Pliocene-Quaternary and could have stopped at certain time in the past. The current geomorphic processes are mainly headward erosion in the upstream.References Allen, C.R., Gillepie, A.R., Han, Y., Sieh, K.E., Zhu, C., 1984. Red River and associated faults, Yunnan province, China: Quaternary geology, slip rates, and seismic hazard, Geological Society of America Bulletin,  686-700, 21 fig.Azor, A., Keller, E.A., Yeats, R.S., 2002. Geomorphic indicators of active fold growth: South Mountain-Oak Ridge anticline, Ventura basin, southern California. Geological Society of America Bulletin 114, 745-753.Chen, Y.C., Sung, Q., Cheng, K.Y., 2003. Along-strike variations of morphotectonic features in the Western Foothills of Taiwan: tectonic implications based on stream gradient and hypsometric analysis. Geomorphology 56, 109-137.Delcaillau, B., Deffontaines, B., Floissac, L., Angelier, J., Deramond, J., Souquet, P., Chu, H.T., Lee, J.F., 1998. Morphotectonic evidence from lateral propagation of an active frontal fold; Pakuashan anticline, foothills of Taiwan. Geomorphology 24, 263-290.Delcaillau, B., Laville, E., Amhrar, M., Namous, M., Dugué, O., Pedoja, K., 2010. Quaternary evolution of the Marrakech High Atlas and morphotectonic evidence of activity along the Tizi N'Test Fault, Morocco. Geomorphology 118, 262-279.El Hamdouni, R., Irigaray, C., Fernández, T., Chacón, J., Keller, E.A., 2008. Assessment of relative active tectonics, southwest border of the Sierra Nevada (southern Spain). Geomorphology 96, 150-173.Font, M., Amorese, D., Lagarde, J.L., 2010. DEM and GIS analysis of the stream gradient index to evaluate effects of tectonics: the Normandy intraplate area (NW France). Geomorphology 119, 172-180.Gardner, T.W., Sasowsky, K.C., Day, R.L., 1990. Automated extraction of geomorphometric properties from digital elevation models. Zeischrift für Geomorphologie Supplemental Band 80, 57-68.Harlin, J.M., 1978. Statistical moments of the hypsometric curve and its density function. Mathematical Geology 10, 59-72.Howard, A.D., 1990. Role of hypsometry and planform in basin hydrologic response. Hydrological Processes 4, 373-385.Huang, X.J., Niemann, J.D., 2006. Modelling the potential impacts of groundwater hydrology on long-term drainage basin evolution. Earth Surface Processes and Landforms 31, 1802-1823.Joshi, P.N,. Maurya, D.M., Chamyal, L.S., 2013. Morphotectonic segmentation and spatial variability of neotectonic activity along the Narmada-Son Fault, Western India: Remote sensing and GIS analysis. Geomorphology 180-181 (2013) 292-306.Keller, E.A., Pinter, N., 2002. Active Tectonics. Earthquakes, Uplift and Landscape. Prentice Hall, New Jersey, 362.Le Duc An, 2003. About the exhumation of metamorphic rocks of Con Voi range. Journal of Sciences of the Earth,No.1, 93-95 (In Vietnamese with English abstract).Le Duc An, Dao Dinh Bac, Uong Dinh Khanh, Vo Thinh, Tran Hang Nga, Ngo Tuan Anh, Nguyen Thi Le Ha, 2004. Geomorphology of Red River Fault Zone and natural hazard.P 459-532. Science and Technics Publishing House, Hanoi (In Vietnamese with English abstract).Le Duc An, Lai, Huy Anh, Vo Thinh, Ngo Tuan Anh, Do Minh Tuan, Tran Hang Nga, 2001. Steps of relief of Convoi Mountain characteristics. Journal of Sciences of the Earth, 23(2), 97-104. (In Vietnamese with English abstract).Leloup, P.H., Arnaud, N., Lacassin, R., Kienast, J.R., Harrison, T.M., Trinh, P.T., Replumaz, A., Tapponnier, P., 2001. New constraints on the structure, thermochronology, and timing of the Ailao Shan-Red River shear zone, SE Asia, Journal of Geophysical Research, B, v. 106, 6683-6732.Leloup, P.H., Chen Wenji, Harrison, T.M., Tapponnier, P., 1994. Timing of shear sense inversion along the Red River fault zone. Int. Workshop on Seismotectonics and Seismic Hazard in South East Asia, Hanoi.Leloup, P.H., Lacasin, Tapponnier, P., Scharer, U., Dalai, Z., Xaohan, L., Zhangshan, Shaocheng, J., Trinh, P.T., 1995. The Ailao Shan -  Red Rive shear zone (Yunnan, China), Tertiary transform boundary of  Indochina. Tectonophysics, v. 251,  pp. 3-84.Leloup, P.H., Lacassin, R., Tapponnier, P., Harrison, T.M., 2001. Comment on “Onset timing of left-lateral movement along the Ailao Shan±Red River Shear Zone: 40Ar/39Ar dating constraint from the Nam Dinh Area, northeastern Vietnam” by Wang et al., 2000. Journal of Asian Earth Sciences 18, 281-292. Journal of Asian Earth Sciences 20, 95-99.Lifton, N. A., Chase, C.G., 1992. Tectonic, climatic and lithologic influences on landscape fractal dimension and hypsometry: implications for landscape evolution in the San Gabriel Mountains, California. Geomorphology 5, 77-114.Luo, W., 1998. Hypsometric analysis with a geographic information system. Computers Geosciences, Vol. 245, No. 8, 815-821.Luo, W., 2000. Quantifying groundwater- sapping landforms with a hypsometric technique. Journal of Geophysical Research, Vol. 105, No. El, Pages 1685-1694, January 25.Mahmood, S. A., and Gloaguen, R.,  2012. Appraisal of active tectonics in Hindu Kush: Insights from DEM derived geomorphic indices and drainage analysis. Geoscience Frontiers 3(4), 407-428.Moglen, G.E., Bras, R.L., 1995. The effect of spatial heterogeneities on geomorphic expression in a model of basin evolution. Water Resources Research 31, 2613-2623.Ngo Van Liem, 2011. Characteristics of landform evolution in relation to recent geodynamics along the Red River Fault Zone, Doctorate thesis, Institute of Geological Sciences, Hanoi (In Vietnamese with English abstract).Ngo Van Liem, Phan Trong Trinh, Hoang Quang Vinh, 2006. The active faults and the maximum earthquakes of the Red River Fault zone in Lao Cai-Yen Bai area, Journal of Sciences of the Earth, Vol. 28, (2), 110-120 (In Vietnamese with English abstract).Ngo Van Liem, Phan Trong Trinh, Nguyen Van Huong, Nguyen Cong Quan, Tran Van Phong, Nguyen Phuc Dat, 2016. Analyze the correlation between the geomorphic indices and recent tectonic active of the Lo River fault zone in southwest of Tam Dao range. Vietnam Journal of Earth Sciences. Vol. 38, No. 1, 1-13 (In Vietnamese with English abstract).Nguyen Quoc Cuong., Zuchiewicz, W., Tokarski. A. K., 1999. Morphotectonic evidence for right-lateral normal slip in the Red River Fault Zone: insights from the study on Tam Dao fault scarp (Viet Nam), J. Geology, Seri B, 13-14, 57-59.Nguyen Xuan Nam, 2015. Quaternary Geology characteristics, present-day tectonic geomorphology of the Da river valley from HoaBinh to Viet Tri and correlation with geological hazards. Doctorate Thesis. Hanoi University of Mining and Geology (In Vietnamese with English abstract).Ohmori, H., 1993. Changes in the hypsometric curve through mountain building resulting from concurrent tectonics and denudation. Geomorphology 8, 263-277.Pedrera, A., Pérez-Peña, J.V., Galindo-Zaldívar, J., Azañón, J.M., Azor, A., 2009. Testing the sensitivity of geomorphic indices in areas of low-rate active folding (eastern Betic Cordillera, Spain). Geomorphology 105, 218-231.Pérez-Peña, J.V., Azañón, J.M., Azor, A., 2009. CalHypso: An ArcGIS extension to calculate hypsometric curves and their statistical moments. Applications to drainage basin analysis in SE Spain. Computers Geosciences 35, 1214-1223.Phan Trong Trinh, Hoang Quang Vinh, Leloup Philippe Hervé, Giuliani, G., Vincent Garnier., Tapponnier, P., 2004. Cenozoic deformation, thermodynamic evolution, slip mechanism of Red River shear zone and ruby formation. Science and Technics Publishing House, Hanoi. P5-72 (In Vietnamese with English abstract).Phan Trong Trinh, Ngo Van Liem, Nguyen Van Huong, Hoang Quang Vinh, Bui Van Thom, Bui Thi Thao, Mai Thanh Tan, Nguyen Hoang, 2012. Late Quaternary tectonics and seismotectonics along the Red River fault zone, North Vietnam. Earth-Science Reviews 114, 224-235.Phan Van Quynh, Vo Nang Lac, and Tran Ngoc Nam, 1995. Some features of late Paleozoic-Cenozoic deformation tectonics on the territory of Vietnam and neighboring areas. In: Geology, Mineral Resources and Petroleum of Vietnam. Geological Survey of Vietnam, Hanoi, 171-183 (in Vietnamese with an English abstract).Phung Thi Thu Hang, 2011. Study and comparison recent active tectonics between the Red River and the Dien Bien - Lai Chau Fault Zones base on geomorphic indices. Master thesis. VNU University of Science, Hanoi.Shahzad, F., and Gloaguen, R., 2011. TecDEM: AMATLAB based tool box for tectonic geomorphology, Part 1: Drainage network preprocessing and stream profile analysis. Computers Geosciences 37, 250-260.Strahler, A.N., 1952. Hypsometric (area-altitude) analysis of erosional topography. Geological Society of America Bulletin 63, 1117-1142.Strahler, A.N., 1957. Quantitative analysis of watershed geomorphology. Transactions of the American Geophysical Union 38, 913-920.Tran Dinh To, 2002. The characterize of  Neotectonics of Red River-Chay River Fault Zone. Doctorate Thesis, Institute of Geological Sciences, Hanoi, (In Vietnamese with English abstract).Tran Dinh To, Duong Chi Cong, Vy Quoc Hai, Matthias Becker, Marina Neuman, 2003. Activity  of Red River fault zone at Tam Dao-Ba Vi derived from GPS data (1994-1996-1998-2000). Journal of Sciences of the Earth, 25(4)PC, 511-515 (In Vietnamese with English abstract).Tran Dinh To, Nguyen Trong Yem, 2001.Amplitude and rate of slip of the Red River Zone in late Cenozoic. Journal of Sciences of the Earth, 23(4), 334-353. (In Vietnamese with English abstract).Tran Ngoc Nam, 1999. Red River Fault zone - focus of the scientific debate. Part II: P-T-t paths and post-metamorphic exhumation, Journal of Sciences of the Earth, No.3, 161-167 (In Vietnamese with English abstract).Tran Ngoc Nam, 2002. Exhumation mechanisms of the Day Nui Con Voi. Journal of Sciences of the Earth, No.3,  286-288 (In Vietnamese with English abstract).Tran Ngoc Nam, Mitsuhiro Toriumi, TetsumaruItaya, 1998. P-T-t paths and post-metamorphic exhumation of the Day Nui Con Voi shear zone in Vietnam. Tectonophysics 290, 299-318.Tran Ngoc Nam., Toriumi, M., Sano, Y., Terada, K., Ta, T.T.,, 2003. 2.9, 2.36, and 1.96 Ga zircons in orthogneiss south of the Red River shear zone in Viet Nam: evidence from SHRIMP U-Pb dating and tectonothermal implications. Journal of Asian Earth Sciences 21, 743-753.Trinh Thi Thuy, 2014. Assessment of modern tectonic activity of the Son La fault zones on the basis of tectonic geomorphology. Master thesis. The University of Science - Vietnam National University, Hanoi (In Vietnamese with English abstract).Wang, P.L., Lo, C.H., Chung, S.L., Lee T.Y., Lan, C.Y., Thang, T.V., 2000. Onset timing of left-lateral movement along the Ailao Shan±Red River Shear Zone: 40Ar/39Ar dating constraint from the Nam Dinh Area, northeastern Vietnam. Journal of Asian Earth Sciences. Volume 18, Issue 3, 1 June 2000, 281-292.Willgoose, G., 1994. A physical explanation for an observed area-slope-elevation relationship for catchments with declining relief. Water Resources Research 30, 151-159.Willgoose, G., Hancock, G., 1998. Revisiting the hypsometric curve as an indicator of form and process in transport-limited catchment. Earth Surface Processes and Landforms 23, 611-623.Zuchiewicz, W., Nguyen Quoc Cuong, Jerzy Zasadni, Nguyen Trong Yem, 2013. Late Cenozoic tectonics of the Red River Fault Zone, Vietnam, in the light of geomorphic studies. Journal of Geodynamics 69, 11-30. 

Pro-poor intervention strategies in irrigated agriculture in Asia: poverty in irrigated agriculture: issues and options: Vietnam

Irrigated farming / Poverty / Farm income / Irrigation management / Institutions / Legal aspects / Water rates / User charges / Participatory management / Privatization / Participatory rural appraisal / Performance indexes / Irrigation programs / Irrigation systems / Pumping / Irrigation canals / Social aspects / Economic aspects / Rivers / Hydrology / Dams / Households / Income / Regression analysis / Drainage / Cooperatives / Water delivery / Water distribution / Rice / Financing / Drought / Vietnam / Red River Delta / Nam Duong Irrigation System / Nam Thach Han Irrigation System / Han River

Results of magnetotelluric survey for studying geothermal system in the Bang area, Quang Binh province

This paper presents the first results from the application of magnetotelluric method (MT) using the new equipment MTU 2000 (Canada) and analysis software to investigate the structure of geothermal area around the Bang hot water source (Quang Binh province). Results of data analysis by MT 1D and 2D models to a depth of 20 km show low resistivity zone in the southwest of Bang hot water (100°C) and allow for interpreting the structural elements of athehydro- geothermal system. This includes a very low resistivity layer at depth of 2 km suggesting a clay cap (heat resistive shield), a relatively low resistivity zone at depth ≥ 2 km reflecting  fractured rocks containing geothermal fluid and hot steam. A lower resistivity body at depth of 12-14 km located about 1.5 km from the hot water source indicates the existence of a heat source or a hot mass of intrusive magma., commonly thought to be sources of typical hydro- geothermal systems potential for energy exploitation. The obtained results not only provide new information for better understanding geothermal resource in the surveyed area, but also point out the methods and technology needed to improve the effectiveness for assessing potential of geothermal resources elsewhere in Vietnam.ReferencesBản đồ Địa chất và khoáng sản Việt Nam tỷ lệ 1:1.000.000. Cục Địa chất và Khoáng sản Việt Nam xuất bản 2004. Lưu trữ Địa chất. Cumming W., 2009: Geothermal resource conceptual models using surface exploration data. In: proceedings, 34th workshop on geothermal reservoir engineering, Stanford University. Data Processing User guide. Phoenix Geophysic Ltd. 2005, 201p. Di Pippo R., 2012: Geothermal Power plant. Principles, applications, case studies. 3rd edition. Elseverdirect, 579p. Doan Van Tuyen, Tran Anh Vu, Nguyen Thi Kim Thuong, 2014: Geochemical Characteristics of Geothermal Hot Water Sources on the Territory of Vietnam. Proceeding, Thirty-Eighth Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, February 24-26, 2014 SGP-TR-202. Duchkov A.D., Nguyen Trong Yem, Dinh Van Toan, and Trinh Viet Bac, 1992: First estimations of heat flow in northern Vietnam. Soviet Geology and Geophysics, Vol. 33, No. 5, pp 92-96. Flynn T., Quy H. H., 1997: Assessment of the geothermal resources of Socialist Republic of Vietnam. Geothermal resources Council Transactions, vol.21, 341-345. IGA report, 2013: Geothermal Exploration best practices: A Guide to resource data collection, analysis, and presentation for Geothermal projects. He Lijuan, 1999: Analysis of heat flow along a transect across the South China Sea. Geothermal Training Programme, Reports 1999, Number 5, 125-140. Hoang Huu Quy, 1998: Overview of the Geothermal potential of Vietnam. Geothermics, Vol.27, n.1, 109-115. Koenig J. et al., 1981: Evaluation of the potential for Geothermal Energy Resources in the SR of Vietnam. Berkeley, CA. Kulinich G.G., Zabolotnikov A.A, Markov Yu., 1989: Cenozoic evalution of the Earth crust and orogeny in South- Eastern Asia (Tiếng Nga). MTU2000: User guide. Phoenix Geophysic Ltd. 2000, 36p. Munoz Gerard, 2014: Exploring for Geothermal Resources with Electromagnetic Methods. Surv Geophys (2014) 35:101-122, Springer, DOI 10.1007/s10712-013-9236-0. Pellerin et al., Johnston M, Hohmann W., 1996: A numerical evaluation of electromagnetic methods in geothermal exploration. Geophysics 61(1996):121-130. Thomas Mathews, et al., 2008: Study on the sozio-economic framework for the use Geothermal energy in Vietnam. Proceedings of the 8th Asian Geothermal Symposium, Hanoi. Trần Huyên, Trương Minh, Nguyễn Tiến Bào, 1999: Về chế độ địa nhiệt ở các bể trầm tích thềm lục địa Việt Nam. Tạp chí Kinh tế Địa chất và Nguyên liệu khoáng. Cục Địa chất và Khoáng sản Việt Nam. Số 18 tháng 2 năm 1999, tr.16-25. Võ Công Nghiệp (chủ biên), 1998: Danh bạ các nguồn nước khoáng và nước nóng Việt Nam. Cục Địa chất và Khoáng sản Việt Nam. Hà Nội, 300tr. Zhdanov M., 2009: Geophysical Electromagnetic Theory and Methods. Methods in Geochemistry and Geophysics, Volume 43. ISSN: 0076-6895 Elsevier, 831pp. WinGLink User guide. Geosystem 200, 182p. www.geosystem.net.

Winter Refuge for Aedes aegypti and Ae. albopictus Mosquitoes in Hanoi during Winter

Dengue occurs throughout the year in Hanoi, Vietnam, despite winter low temperatures 14°C, exceeding the developmental zero point of Ae. aegypti. Although jars, drums and concrete tanks were the dominant containers previously (1994-97) in Hanoi, currently the percentage of residences with concrete tanks was still high while jars and drums were quite low. Our study showed that concrete tanks with broken lids allowing mosquitoes access were important winter refuge for Ae. aegypti. We also indicate a concern about concrete tanks serving as foci for Ae. aegypti to expand their distribution in cooler regions