Macroscopic behavior of bidisperse suspensions of noncolloidal particles in yield stress fluids

We study both experimentally and theoretically the rheological behavior of isotropic bidisperse suspensions of noncolloidal particles in yield stress fluids. We focus on materials in which noncolloidal particles interact with the suspending fluid only through hydrodynamical interactions. We observe that both the elastic modulus and yield stress of bidisperse suspensions are lower than those of monodisperse suspensions of same solid volume fraction. Moreover, we show that the dimensionless yield stress of such suspensions is linked to their dimensionless elastic modulus and to their solid volume fraction through the simple equation of Chateau et al.[J. rheol. 52, 489-506 (2008)]. We also show that the effect of the particle size heterogeneity can be described by means of a packing model developed to estimate random loose packing of assemblies of dry particles. All these observations finally allow us to propose simple closed form estimates for both the elastic modulus and the yield stress of bidisperse suspensions: while the elastic modulus is a function of the reduced volume fraction $\phi/\phi_m$ only, where $\phi_m$ is the estimated random loose packing, the yield stress is a function of both the volume fraction $\phi$ and the reduced volume fraction

HEDGE ALGEBRAS, THE SEMANTICS OF VAGUE LINGUISTIC INFORMATION AND APPLICATION PROSPECTIVE

The report aims to show that hedge algebras model actually the proper qualitative semantics of words of linguistic variables based on the argument that the inherent qualitative semantics of words should be expressed through the order relationships, induced by the word semantics, between the words in their respective variable domains, as required by decision making of human daily lives. This makes the hedge algebra based approach to the word semantics quite different from the existing approaches and become the only approach that can immediately deal with the natural qualitative semantics of words. We explain clearly and systematically distinguished features and properties of this approach to show that these seem to make the approach to be sound and ensure its effectiveness in applications. This approach seems to be promising for development of hedge algebra-based method to solve problems in various application fields. For illustration, we will give a short overview of effective results some of the initial applications of hedge algebras in the fields of knowledge based systems and in fuzzy control

Effect of Polypyrrole on the Electrical, Dielectric and Mechanical Properties of Waterborne Epoxy Coatings

In this context, conducting composite based on waterborne epoxy system and polypyrrole (PPy) was investigated. The polypyrrole was synthesized by chemical oxidation polymerization. Its morphology and chemical structure were confirmed by using field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). Then, PPy was well-dispersed in the epoxy coating and had a good compatibility with the matrix. The effects of PPy on dielectric, electrical and mechanical properties of epoxy/PPy composites was examined. The dielectric constant and electrical conductivity of the coatings increased with addition of PPy fillers. Over to 15 wt. % of PPy loading, the volume resistivity of samples slightly decreased from 6.7 × 1010 to 1.5 × 1010 Ω cm. In contrast, the presence of PPy diminished both impact and abrasion resistance of the epoxy/PPy composites, down to 160 kg cm and 10.2 L/mil, respectively, but they stayed acceptable for the coatings. The results reveal that the epoxy containing polypyrrole is suitable for various electrical and dielectric applications

EVALUATION OF CITIZENS' SATISFACTION WITH THE QUALITY OF PUBLIC ADMINISTRATIVE SERVICES IN THE MEKONG DELTA, VIETNAM

Citizen satisfaction is one of the essential factors reflecting the quality of public administrative services provided by state administrative agencies. The study aims to assess citizens' satisfaction with the quality of public administrative services in the Mekong Delta, Vietnam. Research data were collected from survey results using questionnaires from 792 survey samples in the Mekong Delta, Vietnam. Research results have shown that citizens are satisfied with the quality of public administrative services in the Mekong Delta, Vietnam. At the same time, there are six factors affecting citizens' satisfaction with the quality of public administrative services, including (1) Reliability; (2) Service capacity of staff; (3) Service attitude of staff; (4) The service level of staff; (5) Infrastructure; (6) Administrative procedures. Research results show no difference in citizen satisfaction in gender, age and education groups. Besides, the survey area group has a difference in citizen satisfaction. The research results have theoretical and practical significance for public administration in Vietnam. From the research results, several contents are discussed and proposed to improve citizens' satisfaction with the quality of public administrative services in the Mekong Delta, Vietnam

HIGH PROTECTION PERFORMANCE OF COATING SYSTEMS BASED ON ZINC RICH PRIMER AND FLUOROPOLYMER COATING

Coating systems based on zinc rich primer and fluoropolymer top coat were exposed for 8 years at different atmospheric stations in Vietnam: Hanoi, Ha Long and Nha Trang. For comparison the coating system with zinc rich primer and polyurethane topcoat was also tested. The degradations of coating systems were evaluated by gloss measurement and electrochemical impedance spectroscopy. The obtained results show that coating systems with zinc rich primer and top coatings based on fluoropolymer  and polyurethane topcoats show very high weather resistance and corrosion protection performance, but the systems with fluoropolymer are better than coating system with polyurethane topcoat

Studying and forecasting the evolution of the Day river coastal zone up to the year of 2070

The Day river coastal zone is the place of plentiful and eventful economical activities and the natural habitat of diverse endemic species that should be preserved and developed. According to the updated geological, remote-sensing and oceanographic data sources, this study figures out the actual state, evolutional history and forecasts the development of the Day river coastal zone up to the year 2070, which could be used to improve the effectiveness of the long-term spatial coastal zone management and master planning. Major conclusions are as follows: (i) The Day river coastline has been highly modified since the last 50 years, (ii) The shoreline seaward development tends to gradually decrease in recent years, and (iii) The river-bed continues to be shifted southwestwards in the context of global climate change and sea level rise.Abstract STUDYING AND FORECASTING THE EVOLUTION OF THE DAY RIVER COASTAL ZONE UPTO THE YEAR 2050 Duong Quoc Hung1, Vu Hai Dang1, Phan Dong Pha1, Nguyen Thi Anh Nguyet1, Ngo Bich Huong1, Nguyen Thai Son2 (1) Institute of Marine Geology and Goephysics; (2) Institute of Geography The coastal geographical features including alluvial grouds, estuaries, mangrove forest, etc. are products of the river - ocean interactions, reflect the dynamic equilibrium of the unsustainable ecosystems that are spacial and temporary changing. These areas are also the places of plentiful and eventful economical activities and the natural diversified endemic habitats to be preserved and developed. According to the updated data sources, this study mentions to the actual state, evolution history and developing forecasts for the Day River coastal zone up to the year of 2050, which could be used to inhale the effectiveness of the long-term spacial coastal zone management and master plannin

8-hydroxyquinoline-modified clay incorporated in an epoxy coating for the corrosion protection of carbon steel

In the present work, a well-known corrosion inhibitor (8-hydroxyquinoline (8HQ)) was inserted within the montmorillonite platelets (8HQ-MMT) and the modified clay was incorporated (3 wt.%) into a solvent-free epoxy coating which was afterwards deposited on carbon steel substrates. First, the inhibitive action of 8HQ was investigated by electrochemical methods carried out on a bare carbon steel rotating disk electrode in a 0.1 M NaCl solution. Then, electrochemical impedance measurements were performed to assess the effect of the 8HQ-MMT in the epoxy coating for the corrosion protection. The results were compared with a reference sample constituted by the epoxy coating containing an ammonium quaternary salt-modified clay. It was shown that the two coatings presented good barrier properties. Dry and wet adherence measurements revealed an improvement of the adherence when the 8HQ-MMT was incorporated into the coating by comparison with the reference sample. It was concluded that the 8HQ mainly had an effect at the metal/coating interface but its concentration was too low to afford significant corrosion protection of the carbon steel

Estimating the cost of illness of acute Japanese encephalitis and sequelae care in Vietnam and Laos: a cross-sectional study

Background Japanese encephalitis (JE) is a leading cause of acute encephalitis syndrome and resulting neurological disability in Asia and the Western Pacific. This study aims to estimate the cost of acute care, initial rehabilitation and sequelae care, in Vietnam and Laos. Methodology We conducted a cross-sectional retrospective study using a micro-costing approach from the health system and household perspectives. Out-of-pocket direct medical and non-medical costs, indirect costs, and family impact were reported by patients and/or caregivers. Hospitalization costs were extracted from hospital charts. Acute costs covered expenditures from pre-hospital to follow-up visits while sequelae care costs were estimated from expenditures in the last 90 days. All costs are in 2021 US dollars. Principal findings 242 patients in two major sentinel sites in the North and South of Vietnam and 65 patients in a central hospital in Vientiane, Laos, with laboratory-confirmed JE were recruited regardless of age, sex, and ethnicity. In Vietnam, the mean total cost was $3,371 per acute JE episode (median$2,071, standard error [SE] $464) while annual costs were$404 for initial sequelae care (median $0, SE$220) and $320 for long-term sequelae care (median$0, SE $108). In Laos, the mean hospitalization costs in acute stage were$2,005 (median $1,698, SE$279) and the mean annual costs were $2,317 (median$0, SE $2,233) for initial sequelae care and$89 (median $0, SE$57) for long-term sequelae care. In both countries, most patients did not seek care for their sequelae. Families perceived extreme impact from JE and 20% to 30% of households still had sustained debts years after acute JE. Conclusions JE patients and families in Vietnam and Laos suffer extreme medical, economic, and social hardship. This has policy implications for improving JE prevention in these two JE-endemic countries

Abnormal features of oceanographic characteristics in upwelling Vietnam waters under impact of El Niño events

The summer upwelling that occurs in coastal waters of South Central Vietnam is one of the major hydrographic features in the South China Sea. A weakening of the upwelling after major El Niño events was observed in the literature for previous El Nino events and was verified here from the analysis of new satellite image data sets of sea surface temperature (SST) and surface wind. The analysis of empirical orthogonal function (EOF) from of monthly SST as well as of temporal and spatial variations of SST and wind force allow us to identify abnormal characteristics in ocean surface water that happened after El Niño episode, in agreement with previous studies. Those abnormal characteristics in Vietnam upwelling waters appeared mainly during the summers of 1998, 2003, 2010 and 2016 years for the El Niño decline phase. The upwelling weakening during El Niño decline episodes is associated with the following signals: (1) Wind force and Ekman pump are very weak; (2) the cold  and high chlorophyll-a  tongue is shifted northward but not extended eastward; (3) for years when El Nino occurs, SST strongly increases and reaches a peak in May or early June of next year, during the declining phase of El Niño episode; (4) upwelling phenomenon typically occurs during August and not July. Using a reanalysis dataset derived from the HYCOM/NCODA system coupled with a local Finite Element Model (FEM) allow us to complete our knowledge about the abnormal oceanographic characteristics of deeper water layers after El Niño episodes. The analysis of spatial variations of oceanography fields derived from HYCOM/NCODA/FEM system along zonal and meridional sections and vertical profiles as well as the results obtained from water mass analysis allow us to identify in details the abnormal oceanic characteristics of deeper water layers during the declining  El Niño phase. Those are; (5) Sea water in both surface and deeper water layers were transported dominantly northward  but not eastward; (6) The thermo-halocline layer in South Vietnam upwelling center was deeper (about 90 -100m), compared with previous El Nino and normal years (50-60 m and 35-40 m, respectively); (7) Extreme global warming in recent years (2012-2016) pressed the thermo-halocline layer in upwelling center deeper (90-100 m) during summer. Under the influence of the ocean global warming, this process should progress continuously, the depth of thermo-halocline layer should become therefore deeper and deeper in next years.References Barthel, K., R. Rosland, and N. C. Thai, 2009. Modelling the circulation on the continental shelf of the province Khanh Hoa in Vietnam, J. Mar. Syst., 77(1-2), 89-113. Bui Hong Long, Tran Van Chung, 2009. Calculations of currents in the upwelling region along south-central Vietnamese coast, using three dimensions (3-D) nonlinear model”, Journal of Marine Science and Technology - VAST, 9(2), 01-25 (in Vietnamese). Bui Hong Long, Tran Van Chung, 2017. Preliminary studies on the impact of climate change on the upwelling region south Central Vietnam in summer.  Journal of Marine Science and Technology - VAST , 17(1), 01-19 (in Vietnamese). Colling, A., 2001. Ocean Circulation, Open University Course Team. Second Edition. ISBN 978-0-7506-5278-0. Dippner, J. W., and N. Loick-Wilde, 2011. A redefinition of water masses in the Vietnamese upwelling area, J. Mar. Syst., 84(1-2), 42-47. Hale, W.G, Margham, J.P,  and Sauder, V.A, 2005. Collins Dictionary of  Biology 3rd . London: Collin. Huang, Q.-Z.,W.-Z. Wang, Y. S. Li, and C. W. Li, 1994. Current characteristics of the South China Sea, in Oceanology of China Sea, edited by D. Zhou, Y.-B. Liang, and C. K. Tsebgm, 39-47, Kluwer Acad., Norwell, Mass. H.E. Hurlburt, E.P. Chassignet, J.A. Cummings, A.B. Kara, E.J. Metzger, J.F. Shriver, O.M. Smedstad, A.J. Wallcraft, and C.N. Barron, 2008. Eddy-resolving Global Ocean Prediction, in M. Hecht and H. Hasumi, eds., Ocean Modeling in an Eddying Regime, Geophysical Monograph 177 (American Geophysical Union, Washington, DC ). Knauss, J.A., 2005. Introduction to Physical Oceanography, Waveland Press. Second Edition. ISBN 978-1-57766-429-1. Kuo. N. J, Zheng. Q, Ho C. R, 2004.  Response of Vietnam coastal upwelling to the 1997-1998 ENSO event observed by multisensor data, Remote sensing of Environment, 15 January, 89(1), 106-115. Le Phuoc Trinh, Nguyen Tien Dung, Nguyen Van Minh, Le Minh Tan, Nguyen Kim Vinh, 1981. A proposal of studies on the upwelling of Southeastern coast of Vietnam, Collection of Marine Research Works, 2(2), 13-31 (in Vietnamese). Nguyen Van Long and Vo. Si  Tuan, 2010. Status of coral reefs in Vietnam following the 2010 coral bleaching event. In: Kimura T, Tun K (eds) Status of Coral Reefs in East Asian Seas Region: Ministry of the Environment, Japan, 29-49. NOAA National Centers for Environmental Information, State of the Climate: Global Analysis for Annual 2010, published online January 2011, retrieved on March 25, 2017 from http://www.ncdc.noaa.gov/sotc/global/201013. Ose, T., Y. Song, and A. Kitoh, 1997. Sea surface temperature in the South China Sea: An index for the Asian monsoon and ENSO system, J. Meteorol. Soc. Japan., 75, 1091-1107. Pohlmann, T., 1987. A three dimensional circulation model of the South China Sea., 245-268. In Three-Dimensional Models of Marine and Estuarine Dynamics, ed. by J. J. Nihoul and B. M. Jamart, Elsevier, New York. Qu, T,  Kim, Y.Y, Yaremchuk, M., Tozuka. T, Ishida, A, Yamagata, T., 2004. Can Luzon strait transport play a role in conveying the impact of ENSO to the South China Sea J. Clim. 17, 3644-3657 Shaw, P. T., and S. Y. Chao, 1994.  Surface Circulation in the South China Sea, Deep-Sea Res., I(41), 1663-1683. Siswanto, E., H. Ye, D. Yamazaki, and D.L. Tang 2017. Detailed spatiotemporal impacts of El Niño on phytoplankton biomass in the South China Sea, J. Geophys. Res. Oceans, 122, doi:10.1002/2016JC012276. Sverdrup, H.U., M.W. Johnson and Fleming, R.H., 1942. The Oceans: their physics, chemistry and general biology. Prentice Hall, New York, 1087p. Tang D. L., H. Kawamura, H. Doan Nhu, and W. Takahashi, 2004. Remote sensing oceanography of a harmful algal bloom off the coast of southeastern Vietnam, J. Geophys. Res., 109, C03014, doi:10.1029/ 2003JC002045. Thai Minh Quang, 2016. Studies on influence of  2016.  El Niño event to coral bleaching phenomena in coastal waters in Ninh Hai - Ninh Thuan province. Technical report of  basic research pro­ject funded by Institute of Oceanography - the Vietnam Academy of Science and Technology (in Vietnamese). Tong Phuoc Hoang Son, Vo Van Lanh and Lau Va Khin, 2005. Application of empirical orthogonal function (EOF) for studying thermal structure in sea surface water in South China Sea. The 26th Asian Remote sensing Conference, 7-11 November 2005 in Hanoi. Tran Van Chung, Bui Hong Long, 2016. Effect of temperature field and anomalies of sea water level in East Vietnam Sea in relationship to global climate change - Journal of Marine Science and Technology - VAST, 16(3), 255-266 (in Vietnamese). Vo Van Lanh, 1995. The environmental characteristics of strongly upwelling waters in south of Vietnam and its ecological impacts. Technical report of National project KT03.05. Institute of Oceanography, 480p (in Vietnamese). Vo Si Tuan, 2000. The corals at Con Dao archipelago (South Vietnam): before, during and after the bleaching event in 1998. In: Proceeding of 9th International Coral Reef Symposium, Bali, Indonesia, 23rd-27th October, 895-899. Wang B., An S., 2005. A method for detecting season-dependent modes of climate variability: S-EOF analysis. Geophys. Res. Lett., 32, L15710. Wyrtki K., 1961. Physical oceanography of the Southeast Asian waters, Naga Rep. 2, 195p, Scripps Inst. of Oceanogr., La Jolla, Calif. Xie S.-P., Q. Xie, D. Wang and W. T. Liu, 2003. Summer upwelling in the South China Sea and its role in regional climate variations, J. Geophys. Res., 108(C8), 3261, doi:10.1029/2003JC001867. Xie S.-P., C.-H. Chang, Q. Xie and D. Wang, 2007. Intraseasonal variability in the summer South China Sea: Wind jet, cold filament, and recirculations, J. Geophys. Res., 112, C10008, doi:10.1029/2007JC004238