1,675 research outputs found
Vietnam : Ha Loc : Collines gréso-schisteuses altérées
No full textFonds "Pierre Usselmann sur le Vietnam" : photographie du lieu dit Ha Loc à l'ouest de Viet Tri. On aperçoit des collines gréso-schisteuses altérées, soumises à un nivellement et à un ravinement après un défrichement. Quelques palmiers demeurent de la végétation initiale. Fond de vallée plat et mal drainé, aménagé en rizière (commentaires de l'auteur)
Vietnam : Ha Loc : Large fond de vallée alvéolé
No full textFonds "Pierre Usselmann sur le Vietnam" : photographie du lieu dit Ha Loc à l'ouest de Viet Tri. Très large fond de vallée alvéolé au pied de colline en demi orange. Difficulté du drainage et conservation de l’eau par barrages
Vietnam : Ha Loc : Vallées barrées par digue de terre
No full textFonds "Pierre Usselmann sur le Vietnam" : photographie du lieu dit Ha Loc à l'ouest de Viet Tri. Le fond de vallées est barré par une digue de terre pour la conservation de l'eau et pour la pisciculture. Les rizières ont reçu les premiers labours avant repiquage (commentaires de l'auteur)
Dynamic structural response of Core-Loc
No full textThe Core-Loc, invented and developed at the Waterways Experiment Station (WES), is a new-generation, optimized breakwater concrete armor unit for protecting shoreline and navigation structures.Because of the very difficult construction, in-service, and repair conditions associated with high-energy wave environments, a need was identified to characterize the dynamic impact structural response of the Core-Loc. The most common method of accomplishing this goal is the drop test. Drop tests are used to evaluate the structural performance of a given armor unit when it is exposed to impact loads. During the test, the armor unit is dropped from incrementally increasing heights onto a rigid concrete base until the unit breaks apart. In this case, the drop heights were increased in 25-mm increments until the units totally failed
Tourists satisfaction towards Bao Loc city, Vietnam
No full textBao Loc City is the new tourism destination in Lam Dong province, Vietnam, where more and more tourists have been drawn to pay a visit. This study aims to test the correlative impact of tourism service quality factors on satisfaction of the tourists who have visited Bao Loc City. The key theory used in this study is SERVQUAL scale. The survey sample consists of 350 tourists who stayed overnight in Bao Loc City in the last quarter of 2019; 315 valid survey questionnaires could be used for the analysis. The research applied Cronbach’s Alpha, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), structural equation modeling (SEM), and bootstrap test. The results show that the satisfaction of the tourists who have visited Bao Loc City has been affected statistically by three factors: (1) Responsiveness; (2) Reliability; and (3) Empathy, which were ranked by descending importance. Surprisingly, the research found that Tangibles and Assurance do not have an impact on tourists’ satisfaction towards Bao Loc City. The research formulates some suggestions to the city policy-makers and the tourism businesses management in Bao Loc City in order to enhance tourists’ satisfaction through improving the tourism service quality at Bao Loc City
Role of Hole Trap Sites in MoS2 for Inconsistency in Optical and Electrical Phenomena
No full textBecause of strong Coulomb interaction in two-dimensional van der Waals-layered materials, the trap charges at the interface strongly influence the scattering of the majority carriers and thus often degrade their electrical properties. However, the photogenerated minority carriers can be trapped at the interface, modulate the electron-hole recombination, and eventually influence the optical properties. In this study, we report the role of the hole trap sites on the inconsistency in the electrical and optical phenomena between two systems with different interfacial trap densities, which are monolayer MoS2-based field-effect transistors (FETs) on hexagonal boron nitride (h-BN) and SiO2 substrates. Electronic transport measurements indicate that the use of h-BN as a gate insulator can induce a higher n-doping concentration of the monolayer MoS2 by suppressing the free-electron transfer from the intrinsically n-doped MoS2 to the SiO2 gate insulator. Nevertheless, optical measurements show that the electron concentration in MoS2/SiO2 is heavier than that in MoS2/h-BN, manifested by the relative red shift of the A1g Raman peak. The inconsistency in the evaluation of the electron concentration in MoS2 by electrical and optical measurements is explained by the trapping of the photogenerated holes in the spatially modulated valence band edge of the monolayer MoS2 caused by the local strain from the SiO2/Si substrate. This photoinduced electron doping in MoS2/SiO2 is further confirmed by the development of the trion component in the power-dependent photoluminescence spectra and negative shift of the threshold voltage of the FET after illumination. © 2018 American Chemical Society1111sciescopu
Probabilistic design of Core-loc armoured breakwaters
No full textDeterministic design methods are commonly used to determine preliminary breakwater designs. Partial safety factors take into account previous experiences and provide a robust preliminary design. However, local circumstances can prove to differ considerably compared to average design conditions and stochastic variations in breakwater strength parameters are commonly neglected. With new armouring techniques, such as Core-loc armouring, the uncertainties about the armour strength are relatively large. Design guidelines include a safety factor, but often an additional safety margin is applied in the final design of the armouring to ensure stability. This can result in structure strengths more, or less, than locally required. The economic optimum geometry with the lowest costs is possibly not achieved. These costs consist of the initial construction cost, the collapse damage cost and the economic damage cost due to downtime. To include the damage cost or risk (= failure probability x economic consequence) of breakwater collapse and functional failure, a probabilistic approach can be used to determine the failure probabilities. In Veracruz, Mexico, the port authority of the Port of Veracruz investigates the feasibility of a large port extension next to the existing port of Veracruz. In the preliminary layout a Core-loc armoured breakwater is anticipated to provide shelter at a container terminal and quay location. Deterministic design methods result in an element weight of 18.7t (8.5m3). Two construction methods are evaluated: a water-based and a land-based construction method, with crest heights of 3m +SWL and 11m +SWL respectively. In this deterministic evaluation the economic consequences of functional failure are not taken into account, but both alternatives fulfilled the harbour tranquillity restrictions by the port authority: a maximum downtime of 5%. The water-based construction method is elected as the best construction method, due to lower construction costs of 110.7 million. A crest height of 7m +SWL complies with an allowable downtime of approximately 0.2%. The downtime costs are of considerable more influence than estimated by the port authority. Also the consequences of a breakwater collapse result in a 65% heavier element weight. The discounted total costs over the lifetime of the breakwater are 219 million for the deterministic design. The collapse costs and downtime costs have a significant influence on the total costs over the lifetime and therefore on the economic optimal geometry of the breakwater. A more robust design than deterministically derived can reduce the total cost over the lifetime by almost 50%.Civil Engineering and Geoscience
Valuation of the rice sector in the Quang Dien district, Vietnam : A case study of the rice sector in three communes in the Quang Dien district Thua Thien Hué Province, Vietnam
No full textThe Tam Giang - Cau Hai lagoon is the largest of its kind in South East Asia and covers an area of 22,000 ha. The lagoon is located in the area with the highest rainfall in Vietnam; there are two main seasons, a dry and a wet season. Seasonal problems to the productivity of rice can thus change from flooding, to drought and salinity intrusion. The water quality in the lagoon is very different over the seasons, due to the mixing of the water from the main rivers in the area, with water from the sea in the lagoon. Over the last two decades, aquaculture extension inside the lagoon and an increased urban use of water has caused less water to flow into the lagoon. The uncontrolled extension of aquaculture ponds has also caused a lack of water circulation, which is especially a big problem for ponds with concrete dikes. This has caused a deterioration of the water quality inside the lagoon, which has negative consequences for the aquaculture sector. The decreased inflow of freshwater is also causing the brackish water inside the lagoon to move more land inwards, what is causing salinity intrusion in lagoon bordering communes. To improve the inflow of freshwater there are three new dams being created in the river basin. This should help to stabilize and restore the ecosystem and gives extra opportunities for irrigation. A salinity intrusion barrier has also been created and the sea-outlet will be enlarged to further increase the circulation of water. Most people in the lagoon bordering communes depend for the main part of their income on agriculture and aquaculture. The high food price and the failure of many aquaculture and agriculture crops nowadays place many farmers under difficulties and they will remain to live below the poverty line. To improve the livelihood of farmers, new water infrastructure will be created and the effect of these new dams and flood protection on the rice sector in different communes will be assessed in this thesis. Three communes have been studied and five main factors have been taken into account which could influence the productivity of rice: variety, soil type, state of the irrigation system, input of chemicals and input of nutrients. Differences in these factors cause different yields, but are also related to each other. Certain varieties of rice are only suitable for certain soils and the soil type is impossible to change. GIS maps have been made of the above factors in the different areas together with the main limitations
Merging SoC and LOC Together
No full textA promising combination of the semiconductor integrated System-on-a-Chip (SoC) with the Lab-on-a-Chip (LOC) is brought in this paper. In this paper, we propose a new technology which enables monolithic integration of the self-assembled biological system, the MEMS structure, the microfluidic system, and CMOS electronic circuits together. Utilizing this approach, more functionality is introduced into the SoC, while the LOC becomes more intelligent and controllable. A Post-CMOS fabrication approach that meets the requirements is demonstrated to validate the idea.Engineering, Electrical & ElectronicPhysics, AppliedEICPCI-S(ISTP)
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