Hanoi University

The paper analyses the forced vibration of cracked continuous multi-span functionally graded nanobeams based on the nonlocal elasticity theory (NET), Euler-Bernoulli beam theory (EBT), and the dynamic stiffness method (DSM). The NET accounts for the nanoscale size effect of the structure. A crack model using three springs with stiffness dependent on the crack depth is proposed. The equations of motion are derived using Hamilton's principle, NET, and EBT. Various boundary conditions are formulated from the weak form of the equations of motion, thereby overcoming the nonlocal paradox. The reliability of the proposed method is verified through comparison with published results. The effects of geometric, material, nonlocal, and crack parameters on the forced vibration behaviour of continuous multi-span nanobeams are analysed in detail.

Abstract The North-Central coasts of Vietnam are vulnerable due to the effects of global warming and sea level rise. With quite mildly sloping foreshore, these low-lying coasts have been modelled in a non-hydrostatic and phase solving SWASH to investigate the spectral wave period at nearshore and then compare the empirical equation proposed by Hofland et al., 2017. Especially, the ratio of the predicted spectral wave period at shore to deep water was overestimated in comparison with the previous research, reaching up to 1.9 for the milder slope. Furthermore, a simulation of wave energy spectra measured in Altomare et al., 2016 was also considered in this research. A well-matched result can be seen in both physical observations and modeling calculations. A comparison was further investigated for a mild seabed with a rising sea level. Notably, the significant wave height at nearshore increases by approximately 1.4 times when sea levels rise, even while the wave characteristics at the offshore boundary remain the same.

Most previous research about the dangers of extreme weather events was applicable to populations in high-income countries. Data summarising harms related to extreme weather events in low-income settings are lacking. A systematic review thematically summarising evidence about weather event-linked harms and responses in low- and lower-middle-income countries was conducted. Peer-reviewed and grey literature was systematically searched and selected. Data were extracted about harms, responses and outcomes relevant to six WHO building blocks of healthcare systems. Framework analysis was used to identify predominant themes related to harms, responses and the WHO building blocks. In total, 183 reports were included. Flooding and high winds were the most common types of extreme weather events documented. The main community experience themes identified were the displacement of populations and disruption. The main themes identified for health service delivery were vulnerability, disruption and resilience. Documented examples of resilience or recovery were far fewer for all six WHO healthcare system building blocks than descriptions of vulnerability and disruption. Extreme weather events can be highly disruptive and harmful to healthcare systems and communities in LMIC settings that are often already highly vulnerable.

Abstract This study examines the free vibration and dynamic response of sandwich plates featuring a functionally graded porous (FGP) core and laminated carbon fiber-reinforced polymer (CFRP) face sheets through numerical simulations. The theoretical framework employs Reddy’s third-order shear deformation theory (RTSDT) combined with the Ritz method to formulate the governing equations, while the dynamic solution is computed using the Newmark integration scheme. The numerical results are verified by comparison with established benchmarks to confirm accuracy. Key mechanical properties, including normalized natural frequency and time-dependent displacement, are evaluated for a rectangular sandwich plate, providing insights into the optimization of porous-core sandwich structures.

Background: The objective of this study was to deacribe the epidemiological characteristics, clinical and laboratory features at admission of scrub typhus at a local hyper-endemic area-Khanh Hoa province, central Vietnam. Methods: From August 2018 to March 2020, a hospital-based active surveillance was applied to collect suspected adult scrub typhus cases from 9 public/district hospitals. A community survey was conducted to investigate epidemiological factors. PCR and ELISA IgM tests were applied to confirm cases. Using standardized questionnaires, trained health staffs gathered demographic, clinical and laboratory data, and assessed patients’ household conditions, personal behaviours/protective equipment, and vector exposure. Data was recorded using Open data kit (ODK) on Android devices and analysed with STATA version 15. Results: Thirty-two confirmed cases were identified and analysed, with males accounting for 56.3%. Of these, 56.2% were farmers or worked in forests/mountain fields/garden. About 60% engaged in risky behaviours (urinating in the forest/near bushes/field; passing riverside; resting directly on household floor). About 96.9% lived in poor sanitation households and 60% always saw mice around their homes. Despite 72% worked in hazardous environment, only 34.4% used personal protective equipment. Common clinical symptoms beside fever included headache (84.4%), fatigue (75.0%), myalgia (68.8%), heart rate>90/min (50.0%), lymphadenopathy (34.4%). An eschar was found in 59.4%. Abnormal laboratory findings included neutrophils>70% (53.3%), lymphocytes<20% (65.6%), a neutrophils/lymphocytes ratio (<1 or >2) (60.0%), platelet<150,000/ml (56.3%), and AST/AL ≥40U/l (86.7%). Conclusions: Comprehensive consideration of epidemiological features, clinical and laboratory examination is crucial for diagnosing scrub typhus upon admission. Clinicians in endemic areas need enhance their understanding of local scrub typhus.

Abstract Under globalization and interconnectedness, tourism fosters cross-cultural understanding and drives economic growth while promoting inclusive and sustainable development. As a result, sustainable tourism, which prioritizes more than profit-seeking, has gained increasing support from governments and citizens. Despite its potential, challenges such as governance gaps, social stratification, and climate risks persist, particularly in Asia. This chapter explores key trends, principles, and types of sustainable tourism through global examples. It examines its advantages over traditional tourism and discusses the prospects of sustainable tourism. Through comparative analysis, this study highlights sustainable tourism’s role in achieving long-term development goals.

<title>Abstract</title> In this study, a bio-based polyamide 11 (PA11) composite reinforced with alkali-treated ramie fiber (tRF) was successfully fabricated by hot pressing. To identify optimal treatment conditions, ramie fibers were subjected to alkaline treatment using NaOH concentrations of 0%, 1%, 3%, and 5% by weight. Treatment of ramie fibers with a 3% NaOH solution led to a remarkable 137.5% increase in tensile strength compared to untreated fibers, alongside improved surface characteristics and fiber purity. As a result, the PA11/tRF composite substantially improved overall performance. Specifically, tensile strength increased by 131.45% and flexural strength by an impressive 390.51% compared to neat PA11. Advanced characterization techniques, including dynamic mechanical thermal analysis (DMTA), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), confirmed strong interfacial interactions and enhanced thermal stability of the PA11/ramie fiber composite. These outstanding results demonstrate the effectiveness of alkali-treated ramie fibers in reinforcing PA11, establishing the PA11/tRF composite as a strong candidate for sustainable, high-performance, and eco-friendly material applications.