https://tcsj.utc.edu.vn/index.php/tcgtvt Transport and Communications Science Journal (TCSJ) vi-VN Tạp chí Khoa học Giao thông vận tải 1859-2724 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/3029 Nonlinear analysis serves as a fundamental framework for modeling diverse phenomena in modern science and engineering. Within this field, equilibrium problems provide a powerful tool that not only unifies diverse mathematical models, such as variational inequalities and fixed point problems, but also effectively characterizes various phenomena in various scientific disciplines. Over the past decades, dynamical systems have emerged as an effective method for finding solutions to these problems due to their continuous-time nature and stability properties. This paper investigates a novel regularized dynamical system of extragradient-type specifically designed to solve monotone equilibrium problems. The primary challenge addressed is ensuring the existence of a global solution and achieving strong convergence under mild assumptions. Our methodological approach involves constructing a continuous-time trajectory governed by a regularization term and an extragradient-type structure. We first prove the existence and uniqueness of a strong global solution to the proposed system. Subsequently, the asymptotic behavior of the system is analyzed, demonstrating the strong convergence of the generated trajectories toward a specific solution of the original equilibrium problem. Lastly, a time discretization scheme is implemented, leading to a new iterative regularized extragradient-type algorithm enhanced by relaxation parameters. The main results confirm that the proposed dynamical approach not only guarantees theoretical stability but also provides a robust computational platform for monotone equilibrium problems. The findings of this study offer significant insights into the development of efficient continuous-time optimization methods and contribute to the broader understanding of regularization techniques in nonlinear analysis. Ha Nguyen Hai ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1155 1169 10.47869/tcsj.77.9.3 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/2779 Static configuration analysis of multi-segment mooring systems equipped with clump weights poses a significant computational challenge due to the high non-linearity and sensitivity of the governing equations. This study proposes an optimization-based approach to determine the equilibrium shape of mooring lines, bypassing the limitations of traditional trial-and-error or simplified analytical methods. By incorporating the fundamental catenary equations with force balance and displacement continuity conditions into the objective function, the problem is reformulated as a search for the optimal inclination angle at the lower point of each segment. Two metaheuristic algorithms, Particle Swarm Optimization (PSO) and Genetic Algorithm (GA), are implemented to solve the system of equations. Results demonstrate that the proposed method achieves high accuracy when validated against Finite Element Analysis (FEA), yielding negligible discrepancies (maximum error of 0.3% for inclination angles and 0.0% for mooring tensions). The study highlights that PSO exhibits superior convergence speed and stability compared to GA, particularly in complex configurations involving multiple clump weights. Pham Quoc Hoan ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1128 1137 10.47869/tcsj.77.9.1 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/2993 The Keccak-f[1600] permutation underlies the Secure Hash Algorithm 3 (SHA-3) family of cryptographic hash functions, widely used for data integrity and, increasingly, in post-quantum cryptographic hardware. Iterative implementations reuse one round datapath for all 24 rounds through a wide feedback multiplexer, a resource-efficient choice whose timing has not previously been measured with post-route accuracy. This study analyzes an iterative SHA3-256 core implemented on a Xilinx Artix-7 field-programmable gate array (FPGA) and cross-checked on a Virtex-7 device, comparing post-synthesis and post-route timing and evaluating two fan-out-reduction techniques and a multicycle-path exception. The same design was also taken through a complete register-transfer level (RTL) to GDSII flow on a 45 nm process as an application-specific integrated circuit (ASIC), using an in-house-characterized standard-cell library and a widely used public library, with functional correctness verified against reference test vectors. Post-synthesis estimates underestimate the critical-path delay of the feedback-select path by up to 2.8×, none of the three mitigation techniques improves the operating frequency, and the bottleneck is architecture-induced rather than technology-dependent. The in-house library achieved a signed-off implementation with zero design-rule check (DRC) and layout-versus-schematic (LVS) violations, whereas cell-level verification found manufacturing-grid violations in the public library that prevented a comparable signoff. Ngoc Nguyen Thanh Khiem Nguyen Dac Duy Doan Duc Hieu Tran Trong Tai Nguyen Anh Quynh Chu Thi Ngoc ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1138 1154 10.47869/tcsj.77.9.2 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/2953 Wire arc additive manufacturing (WAAM) of Inconel 718 thin walls requires careful parameter selection to balance geometric accuracy and surface quality. In this study, the effects of wire feed speed (wfs) and travel speed (v) on the effective width (EW), total height (TH), and surface roughness (Sa) of 20-layer walls fabricated by cold metal transfer (CMT)-WAAM process were first analyzed through a full factorial experiment design. To resolve the trade-off between productivity and surface integrity, a multi-criteria decision-making framework integrating Entropy weight method (EWM) with COPRAS and WASPAS methods was applied. The analysis of variance (ANOVA) results reveal that wfs primarily governs EW, while v dominates TH and Sa. Both COPRAS and WASPAS optimization techniques consistently identify wfs = 6 m/min and v = 40 cm/min as the optimal condition, achieving high deposition height with acceptable surface roughness. The proposed framework offers a robust strategy for optimization in CMT-WAAM of Inconel 718 superalloys. Le Van Thao Phung Chi Tinh Do Manh Tung Mai Dinh Si Nguyen Van Son Do Ba Tinh Bui Manh Cuong Doan Tat Khoa ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1211 1225 10.47869/tcsj.77.9.7 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/2971 A semi-analytical model is developed for the electro-thermoelastic free vibration of functionally graded porous sandwich plates with orthogonal stiffeners. The plate comprises a PoFGPie top face sheet, a porous metal-foam core, and a fully dense stiffened FGM bottom face sheet. A four-variable shear deformation theory (HSDT4), the Lekhnitskii smeared-stiffener model, and the pb²-Ritz method are combined in a unified formulation. A cosine-linear electric potential and uniform (UTR), linear (LTR), and nonlinear (NLTR) temperature rises are considered. The model is validated against published 3D, finite-element, and coupled-field solutions. Parametric studies cover core porosity, material gradation, layer thickness, stiffeners, voltage, geometry, boundary conditions, and thermal loading. Within the investigated ranges, increasing core porosity raises the fundamental dimensionless frequency because mass reduction dominates stiffness loss. Greater stiffener height raises the frequency, but the best stiffener orientation depends on the boundary condition and two-directional stiffening is not always optimal. Negative voltage produces a stiffening effect, positive voltage a softening effect, and thermal loading reduces the frequency, with UTR causing the largest decrease. Vu Van-Tham ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1226 1242 10.47869/tcsj.77.9.8 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/2972 Monitoring the operational condition of cable-stayed bridges is essential for ensuring structural safety and long-term serviceability. GNSS-RTK technology has emerged as an effective solution for continuous, high-precision displacement measurement in structural health monitoring (SHM). However, high-frequency GNSS data are often noisy and unlabeled, posing significant challenges for traditional analysis methods. This study addresses the problem of identifying structural operational states from unlabeled GNSS-RTK data using an unsupervised learning framework. Displacement data collected from two GNSS stations installed symmetrically on a cable-stayed bridge were segmented into hourly windows and preprocessed using Hampel filtering and Kalman smoothing. Feature vectors were then standardized and reduced in dimensionality using Principal Component Analysis, while t-SNE was applied for visualization. Clustering algorithms, including K-Means, hierarchical agglomerative clustering, Gaussian mixture models, and DBSCAN, were implemented and evaluated using multiple internal validation indices and stability metrics. The results reveal a consistent two-state structure in the horizontal displacement component, with K-Means achieving the best performance (Silhouette score up to 0.7006) and perfect stability (ARI = 1.0). Importantly, the clustering results are highly consistent across both stations, indicating strong spatial reliability. These findings demonstrate that unsupervised learning can effectively extract meaningful operational states from GNSS-RTK data, providing a robust and scalable approach for structural health monitoring of large-scale bridges. Cong Tran Duc Giang Le Khanh Huong Ho Thi Lan ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1259 1274 10.47869/tcsj.77.9.10 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/3007 This paper presents a vibration analysis of a truck suspension system using a dependent vibrating half-car model to evaluate its dynamic behavior under tire-road contact and separation conditions. The proposed model consists of four degrees of freedom and considers the coupled motions between the front and rear wheels. A numerical approach is applied to calculate the vertical and roll responses of the suspension system under different road excitations. The equations of motion are formulated by incorporating the tire-road separation condition for both wheels, allowing the transition between contact and separation states to be examined. The effects of road profiles and suspension parameters on the dynamic responses are analyzed in both the time and frequency domains. The results show that considering tire-road separation provides a more realistic prediction of vehicle vibration behavior compared with the conventional assumption of continuous tire-road contact. The findings can be used as a reference for suspension design and for developing control methods aimed at improving vehicle stability and rollover resistance. Quy Nguyen Dang Tu Do Van Trung Le Van Anh Lai Viet Tung Nguyen Dinh Long Le Xuan Manh Le Van ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1198 1210 10.47869/tcsj.77.9.6 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/3086 Tile cut away at room edges wastes material and embodied carbon, yet layout optimizers treat one pattern in one room. This paper develops a two-dimensional layout and packing algorithm: four laying patterns obey a minimum-cut rule, off-cuts are reused across rooms only along precedence-feasible tiling orders searched by simulated annealing, and layouts are compared on waste, cutting effort and an embodied-carbon indicator. Geometry can be read one-way from an Industry Foundation Classes (IFC) model and the indicator covers the tile only, so the framework is neither a complete building information modelling workflow nor a life-cycle assessment. On five computational benchmarks with one tile product per dwelling, default setting-out, a 10 cm minimum cut and nominal joint-free dimensions, reuse lowers the waste of running bond by 53%, and schedule-constrained cross-room reuse lowers waste by 24% and 70% relative to within-room reuse in six- and eight-room apartments (median 37% over 60 random apartments); simulated annealing matched enumeration wherever possible (non-trivially only for six rooms). The eight-room value is a favourable case, because its spans let off-cuts fit later pieces exactly. With 2-3 mm joints and a 2.5 mm kerf the gains are 20-21% and 13-15% (median 28-29%); when as-built span deviations, separate wet-area tiles and one rejected off-cut in five are added, they average 16-17% and 10-18%. Reuse also assumes one production lot; site validation is future work. Hao Nguyen Thi Thu Dien Vo Le Ngoc Vuong Doan Dinh Thien ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1291 1305 10.47869/tcsj.77.9.12 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/3125 This study investigates the nonlinear flexural behaviour of Primitive, Diamond, and Gyroid triply periodic minimal surface (TPMS) concrete beams using the Concrete Damaged Plasticity model in Abaqus/Standard. All beams had identical external dimensions, C30/37 concrete properties, and a nominal solid volume fraction of 50%, allowing topology to remain the main variable. A combined geometric-resolution and mesh sensitivity study was conducted, and the R24 models were adopted as the common comparative reference. Structural performance was evaluated using peak load, secant stiffness, accumulated external work up to a common post-peak load threshold, mass-normalized accumulated work, normalized deformation index, and damage distributions. Primitive exhibited the highest secant stiffness (46.5 kN/mm) and peak load (5.12 kN) but showed localized damage, rapid post-peak load reduction, and the lowest accumulated work (0.93 J). Diamond achieved a slightly lower peak load (4.77 kN) while providing the highest accumulated work (1.85 J) and mass-normalized accumulated work (0.39 J/kg), indicating a favorable balance between strength and work accumulation under the adopted numerical assumptions. Gyroid showed the lowest peak load (3.56 kN) but the highest normalized deformation index (2.16). The results demonstrate a clear topology-dependent trade-off among stiffness, strength, accumulated work, and deformation capacity, and provide preliminary numerical insights for future experimental validation and investigation of load-bearing, permeable TPMS concrete structures. Tuan Tran Anh Hai Hoang Viet Quan Nguyen Hoang Thao Tran Thi Bich Viet Tran Bao ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1170 1184 10.47869/tcsj.77.9.4 https://tcsj.utc.edu.vn/index.php/tcgtvt/article/view/3134 Local scour around bridge piers is a major threat to foundation stability, and accurate prediction of its temporal development is important for bridge safety assessment. This study investigates clear-water local scour around a cylindrical bridge pier using an existing laboratory dataset and three-dimensional CFD-based morphodynamic simulation with REEF3D. The experimental dataset comprises 21 time-resolved scour-depth measurements collected over a 330-min test. The numerical model solves the incompressible RANS equations with the standard k- turbulence model and couples the hydrodynamic solution with the Engelund–Fredsøe bed-load formulation and movable-bed evolution. Mesh-resolution and critical Shields parameter sensitivity analyses were conducted to identify a suitable calibrated configuration. The selected configuration reproduced the measured temporal scour development with satisfactory agreement and captured the characteristic progression from rapid initial erosion through transitional scour growth to gradual stabilization toward quasi-equilibrium. The results indicate that a properly calibrated REEF3D framework can reproduce the temporal development of clear-water pier scour with reasonable accuracy, although broader independent validation is required before general engineering application. Huy Mai Quang Phong Nguyen Dang ##submission.copyrightStatement## 2026-11-15 2026-11-15 77 9 1275 1290 10.47869/tcsj.77.9.11