Factors influencing parents’ choice of school bus transportation for their children in Hanoi
Trang: 1-15 Vu Thi Huong, Thach Minh Quan, Nguyen Thanh ChuongTóm tắtIn the context of rapid urbanization in major Vietnamese cities, students’ daily travel demand has become a growing concern from both social and urban transport management perspectives. This study analyzes the factors influencing parents’ mode choice with respect to school bus usage for primary and lower secondary school students in Hanoi. Data collected from 400 questionnaire surveys were analyzed using descriptive statistics, reliability testing of measurement scales, and binary logistic regression to estimate the probability of parents choosing school bus services. The results indicate that safety perception, service convenience, and trust in the service are the three key factors exerting a positive and statistically significant influence on parents’ mode choice behavior. In contrast, travel cost and home–school distance do not show a significant effect. In addition, parental socio-demographic characteristics (including age, income, and vehicle ownership) differ between users and non-users of school bus services. These findings reflect the characteristics of school-related travel in Hanoi, where safety and service reliability are prioritized by parents over cost considerations. The study provides empirical evidence to support policy formulation and the organization of safe and appropriate school bus systems in the context of Vietnamese urban mobility
Trang: 16-29 Le Xuan Luu, Luong Xuan Binh, Ha Van Quan, Ta Thi HienTóm tắtVibrations of existing structures induced by wind, traffic, and human activities are often ambient in nature. These vibrations typically have low amplitudes, making it challenging to capture their motion with a camera. This paper presents a framework for measuring the displacement of structural ambient vibrations without physical contact using a low-cost camera. The micro-amplitude vibrations of the structure are captured by the camera and then amplified using the Phase-Based Video Motion Magnification (PVMM). The centroid of structural target segments in each image frame is tracked using the proposed Shape-Box Tracking (SBT). Unwanted background objects are removed using the proposed Line-Based Color Selection (LCS). Vibration characteristics are determined using frequency-based analysis and Random Decrement Technique (RDT). Two experiments based on the proposed framework were conducted to demonstrate its effectiveness. The first involved free-decay vibration testing with large amplitudes, while the second focused on ambient vibration with small amplitudes, emphasizing motion magnification. The success of this method paves the way for applying low-cost cameras in the operational measurement of existing structures
Low-power cordic multiplier design using approximate arithmetic for energy-efficient computing
Trang: 30-42 Thanh Dat Nguyen, Van Vu Luyen, Quang Thai Pham, Duy Anh Nguyen, Khanh N. Dang, Nguyen Khanh Linh, Dao Thanh ToanTóm tắtIn digital IC design, low-power CORDIC-based multipliers have attracted significant attention due to their potential to integrate approximate adders for reducing energy and area costs. While CORDIC is hardware-efficient, its precise design still has room for improvement, particularly in terms of power consumption and area overhead. To address this, we present an approach to enhance the CORDIC multiplier using Approx. Adders from the EvoApproxLib library. The proposed design offers multiple variants with different optimization targets: up to 19.3% power reduction in CORDIC + Approx. Adder, 11.5% area savings in CORDIC + Approx. Adder, and 14.7% frequency improvement in CORDIC + Approx. Adder compared to the conventional exact CORDIC multiplier. When applied to Gaussian filtering and Sobel edge detection, optimal variants such as CORDIC + Approx. Adder and CORDIC + Approx. Adder yield PSNR values of 60 and 48 dB respectively, with SSIM values exceeding 0.990, indicating minimal quality loss. The evaluation shows that 8–10 iterations provide the best efficiency-accuracy trade-off, enabling designers to select appropriate variants based on specific application requirements. These results demonstrate the effectiveness of the proposed method for energy-constrained, error-tolerant systems in IoT devices, edge computing, and image processing applications
Trang: 43-57 Tien Dung Vo, V. V. Tatarinov, Van Hieu Nguyen, Van Thuy Do, Hong Minh NguyenTóm tắtMitigating the effects of thermal stress and shrinkage in airfield concrete pavements typically involves dividing the pavement into individual slabs of appropriate dimensions. Under aircraft wheel loading, the slab edges and corners are subjected to the most critical and unfavorable stress states. To reduce these disadvantages, dowel bars must be placed along both the longitudinal and transverse joints to transfer part of the applied load from the loaded slab to the adjacent one. Improper selection of dowel diameter or spacing can significantly diminish the pavement’s load-bearing capacity and shorten its service life. In this study, the finite element software ABAQUS was used to examine the influence of dowel bar diameter and spacing on the stress and deflection responses of airfield concrete slabs subjected to B737-500 aircraft loading. The numerical model considered two commonly used slab thicknesses: 0.30 m and 0.40 m. The results indicate that, for a constant dowel diameter, the deflection and stress increase sharply as dowel spacing increases from 0.1 m to 0.4 m, while changes become negligible beyond 0.40 m. Conversely, when spacing is kept constant, increasing the dowel diameter from 20 mm to 40 mm substantially reduces stress and deflection, with further increases yielding minimal additional benefit. These findings provide useful guidance for selecting appropriate dowel dimensions in the design of airfield concrete pavements
Determinants to blockchain technology adoption: a survey in Vietnam construction enterprises
Trang: 58-69 Nguyen Viet HungTóm tắtIn recent years, blockchain technology has demonstrated significant potential benefits for the construction industry, yet its adoption remains limited. This study investigates the determinants influencing blockchain adoption within construction organizations in Vietnam. The research combined Technology Acceptance Model (TAM) and Technology–Organization–Environment (TOE) framework to identify and organize determinants into latent constructs including technology, organization and environment dimensions. A questionnaire was developed to collect data from 122 construction practitioners, the model was then empirically tested and validated through using structural equation modeling (SEM). The results indicate that technological factors significantly affect users' perceived usefulness and perceived ease of use regarding blockchain technology. In contrast, organizational and environmental factors do exhibit no significant impact on perceived ease of use. Moreover, perceived usefulness emerges as a critical determinant of user acceptance of blockchain technology. Collectively, these insights contribute to valuable data to develop a roadmap for promoting blockchain implementation in the Vietnamese construction industry
Trang: 70-84 Dang Thuy Dong, Dao Huy Bich, Pham Nhu Nam, Pham Thanh Hieu, Nguyen Thi PhuongTóm tắtAdvanced composite materials, with their superior strength-to-weight ratio, durability, and thermal resistance, are increasingly applied in civil engineering for withstanding harsh mechanical and environmental loads. This paper presents a nonlinear stability analysis of cylindrical panels made from a new type of composite material, namely, functionally graded graphene-reinforced metal matrix composite (FG-GRMMC). The panels are stiffened by oblique or orthogonal FG-GRMMC stiffeners. The fundamental formulation is developed using higher-order shear deformation theory (HSDT), incorporating von Kármán geometric nonlinearity. The effects of stiffeners are modeled using an enhanced smeared stiffener technique for both mechanical and thermal effects through coordinate transformation. The governing equations are derived and solved using the Ritz energy method. Different graphene distribution patterns and stiffener orientations are systematically investigated to evaluate their effects on critical buckling and postbuckling responses. The results highlight the significant improvements in structural stability achieved through the use of oblique stiffeners and optimized material, particularly under thermal loading conditions
Study on dynamic load factor for narrow gauge railways. application on Vietnam’s north – south line
Trang: 85-99 Tran Anh Dung, Mai Van Tham, Pham Dinh DaoTóm tắtIn high-speed railways, dynamic load factor has been received many studies recently. This work aims to determine the dynamic load factors of the traditional railway (1000 mm gauge) of North-South railway line in Vietnam. The objective of this research is to determine the dynamic load factors of the track based on the D19E locomotive with an axle load of 13.5 tons, rail P43, and ballast track. Simulation and experimental methods are implemented in the research. The simulation method was performed by SIMPACK software. The experimental method was carried out on a section of the North - South railway line in Vietnam. Based on the obtained simulation results, the dynamic load factors are 1.046, 1.110, and 1.361 corresponding to the speeds V=15km/h, V=30km/h, and V=70km/h. According to the experiment results, the dynamic load factors are 1.113, 1.134, and 1.181 corresponding to the speeds V=15km/h, V=30km/h, and V=70km/h. The results will be a tool for the track design engineer to implement correct design activities, and the design process will be safe and economical. Additionally, the SIMPACK software can be used to determine the dynamic coefficient for railways instead of experimental methods
Trang: 100-111 Hoang Khac Tuan, Pham Ngoc ThachTóm tắtJointed Plain Concrete Pavements (JPCPs) are divided by transverse and longitudinal joints, with dowel bars commonly embedded across transverse joints to ensure adequate load transfer efficiency (LTE) between adjacent slabs. However, joints are often considered the primary source of long-term structural deterioration. Thus, accurate modeling of joint behavior is essential for comprehensive analysis of the structural response of JPCPs systems. This study investigates LTE performance using three-dimensional finite element models developed in ABAQUS, employing three dowel–concrete interaction approaches: (1) surface contact with Coulomb friction; (2) embedded constraint method; and (3) spring connection. All three models produced consistent LTE values and closely matched field measurements. However, notable differences were identified in terms of modeling complexity, mesh density, numerical stability, and the ability to capture local stress around the dowel bars. These distinctions underscore the importance of aligning the modeling approach with the specific objectives of the analysis. The frictional contact model allows for detailed stress evaluation at the dowel–concrete interface but requires greater computational resources and modeling effort. In contrast, the embedded constraint and spring connection methods are better suited for large-scale simulations that focus on overall slab deformation, where local stress analysis at the dowel interface is not required
Trang: 112-126 Doan Thi Noi, Nguyen Hoang Son, Tran Thu PhuongTóm tắtReliable rainfall data are essential for hydrological modelling and infrastructure planning, particularly in mountainous regions where gauge networks are sparse and climate risks are growing. Satellite rainfall products such as Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) and Global Satellite Mapping of Precipitation (GSMaP) have been increasingly applied worldwide, yet their performance in complex terrains remains uncertain. This study evaluates CHIRPS and GSMaP against daily observations from 11 meteorological stations in Northwest Vietnam during 2000–2024 and applies an elevation-based bias correction. Statistical analyses were used to compare accuracy, including RMSE and correlation, and performance maps were generated to reveal spatial error patterns. The results show that CHIRPS achieved lower RMSE but tended to underestimate rainfall at high-elevation stations, while GSMaP yielded slightly higher correlations (R² ≈ 0.74–0.81) but often overestimated rainfall in mid-elevation valleys. Elevation-based correction reduced RMSE, narrowed bias spread across the network, and produced notable improvements at upland sites. These corrected datasets enhance reliability for hydrological simulations and flood risk assessment, especially along National Highway 6, where landslides and flash floods frequently disrupt traffic. Overall, the findings demonstrate the practical value of integrating satellite rainfall with ground observations to supplement precipitation information in ungauged regions, supporting safer and climate-resilient transport infrastructure in mountainous areas
Trang: 127-141 Le Khanh Giang, Tran Duc Cong, Ho Thi Lan HuongTóm tắtGlobal Navigation Satellite System (GNSS) time series are widely used for structural health monitoring (SHM) and deformation analysis, but real-world recordings frequently contain short and long contiguous gaps that degrade downstream interpretation. This study addresses the challenge of accurate imputation for GNSS displacement series by proposing a self-supervised learning framework that trains models directly on real, unlabelled data using contiguous-span masking. We evaluate four neural architectures (ANN, CNN, GRU, LSTM) under a unified pipeline comprising signal denoising (moving-average, Kalman smoothing, Haar wavelet), sliding-window segmentation, Z-score normalization, and middle-region masking. Experiments use a year-long 10-minute-sampled dataset from the Can Tho cable-stayed bridge (sensor can519501, x/y/z components) and assess reconstruction quality via R², MAE, and MSE on withheld masked segments. Results indicate that recurrent architectures, particularly LSTM, produce the most faithful reconstructions: LSTM attains the highest validation R² (≈0.948) and the lowest MAE (≈0.137) and MSE (≈0.052) among tested models, while GRU offers competitive performance and CNN/ANN show substantially weaker recovery. These findings demonstrate that masking-based self-supervision is an effective strategy for GNSS gap recovery and that LSTM-like sequence models are well suited to capture the long-range temporal dependencies in bridge displacement data. The proposed approach enhances the reliability and continuity of GNSS-derived time series for structural monitoring and can inform future multi-sensor fusion and uncertainty quantification work
Trang: 142-153 Nguyen Thi Tuyet Trinh, Dao Duy LamTóm tắtConcrete-filled steel pipe piles have been increasingly used in Mono Steel Pipe Pile Pier (MSPPP) structures because of their high strength, ductility, and construction efficiency. Nevertheless, experimental data regarding their resistance to special lateral loads, particularly those induced by vehicular collision, are still limited. This paper presents a full-scale experimental study on the lateral load-carrying capacity of a concrete-filled steel pipe pile representative of an MSPPP configuration. A full-scale static lateral loading test was performed to investigate the pile response under a monotonically increasing horizontal load applied at the pier level. The loading scheme was intended to simulate an equivalent static condition corresponding to vehicular collision actions specified in TCVN 11823:2017. The experimental results indicate that the tested pile sustained a maximum lateral load of 1,275 kN, which is significantly higher than the equivalent static impact load of 720 kN. The pile showed stable flexural behaviour with substantial lateral deformation capacity, without any evidence of local buckling, material fracture, or abrupt loss of load-carrying capacity. These results demonstrate that full-scale static lateral loading tests constitute a practical and reliable method for verifying the resistance of MSPPP piles subjected to special lateral loads and provide useful experimental evidence for structural design and verification
