Rajamangala University of Technology (Thai: มหาวิทยาลัยเทคโนโลยีราชมงคล), (RMUT), is one of the university systems in Thailand. It has nine universities providing undergraduate and graduate level education. It was elevated to university status in 2005. Before that it was known as Rajamangala Institute of Technology (สถาบันเทคโนโลยีราชมงคล).In September 2016, Prime Minister Prayut Chan-o-cha invoked Section 44 of the interim charter allowing him to form a special panel to take over administration of Rajamangala University of Technology Tawan-ok as it was judged to be incapable of administering itself.
This study proposes a numerical investigation of enhanced thermal performance in a circular tube equipped with periodically arranged, inclined delta wings (DWs) mounted directly on the inner tube walls. The turbulent airflow is evaluated for Reynolds numbers (Re) between 3000 and 21,000 utilizing the finite volume approach along with the Realizable k–ε turbulent model. The analysis is performed in two different phases: solid delta wings (DW) and punched delta wings (PDW). In the solid DW phase, the angle of attack (α) is kept constant at 45°, and geometric parameters include a set of four base/chord ratios (BR = 0.4 to 0.7) and four pitch ratios (PR = 0.5 to 1.5). The forward delta wing (F-DW) constantly outperforms the backward delta wing (B-DW) in terms of heat transmission enhancement, as indicated by comparative analysis of the DWs. In contrast to a smooth tube, the F-DW generates streamwise vortices that greatly boost fluid interaction and heat transmission, but at the sacrifice of rising pressure loss. The greatest Nusselt number (Nu) and friction factor (f) are realized with the F-DW at the narrowest pitch ratio (PR = 0.5) and its highest base ratio (BR = 0.7). Under baseline operating parameters of PR = 0.75 and Re = 3,000, the largest thermal enhancement factor (TEF) values of 2.79, 2.82, and 2.76 are achieved, with corresponding Nu ratios of 7.69, 8.79, and 10.34 for BR = 0.4, 0.5, and 0.6, respectively. In the second phase, a novel perforation approach is employed on the optimal F-DW (BR = 0.5, PR = 0.75) to establish a forward punched delta wing (F-PDW). This cutting-edge F-PDW attains a maximum TEF of 3.01 alongside a Nu ratio of 9.24. The findings show that, as contrasted to solid DWs and smooth tubes, the F-PDW greatly increases overall TEF, indicating its great potential for efficient, smaller heat exchanger applications.
This study addressed the thermal degradation of bioactives during industrial processing by developing and characterising hydrogel beads from Kaew Kamin mango pulp as a clean-label strategy to enhance stability and modify texture. Beads were formulated using a sodium alginate matrix cross-linked with calcium lactate (0.5–1.5 g/100 g) and stabilised with gum Arabic or guar gum (0.2 or 0.4 g/100 g). A factorial experimental design was used to assess the effects of cross-linker concentration, gum type, pump speed, and gelation time on bead properties. The optimised formulation, incorporating 0.4 g gum Arabic/100 g and 1.5 g calcium lactate/100 g, produced at a pump speed of 2 cm/s with a 10 min gelation time, yielded beads with high firmness (33.98 N), low swelling (< 20
The development of paper materials with advanced functionalities offers new opportunities for applications beyond traditional uses. In this study, a fluorine-free and environmentally friendly superhydrophobic coating was fabricated via a simple spray coating method. VTMS-modified SiO2 nanoparticles (VTMS/SiO2) were applied to atmospheric plasma-treated paper using polydimethylsiloxane (PDMS) and KH550 as crosslinking and coupling agents, respectively. The chemical functionalities of the surface and the morphology of the coated samples were characterized by FTIR and SEM. Among the different formulations, the optimum condition, i.e., 15 s plasma treatment followed by coating with 7.5VTMS/SiO2/0.75KH550, resulted in excellent superhydrophobicity with a water contact angle (WCA) of 160.4 ± 0.5° and a sliding angle (WSA) of 4.5 ± 1.1°. In addition, the coating exhibited excellent mechanical resistance and retained its properties after 20 Taber abrasion cycles. Chemical stability under acidic and alkaline conditions was also maintained. Compared to coatings without plasma treatment, the plasma-enhanced surface exhibited significantly improved adhesion and robustness. These results illustrate a scalable, fluorine-free strategy for producing durable, multifunctional paper surfaces suitable for advanced packaging and protective applications.
Commercial motorcyclists face disproportionately high crash rates globally, yet the psychological mechanisms driving their safety behaviors remain inadequately explored, particularly regarding differences between Full-time and part-time riders. This study examines how the Health Belief Model (HBM) influences safety behaviors through risk awareness as a mediating variable, comparing these mechanisms across employment categories. Final analytical sample of 1,827 participants (471 part-time and 1,356 Full-time) across five regions urban centers in Thailand using structured interviews. Structural equation modeling with measurement invariance testing revealed that health motivation, perceived susceptibility, severity, benefits, barriers, and cues to action all positively influenced risk awareness, which in turn positively affected safety equipment use and negatively affected risky riding behaviors. Significant differences emerged between employment categories, with part-time riders showing stronger effects from health motivation and stronger mediating effects of risk awareness, while Full-time riders demonstrated stronger effects from perceived severity and stronger direct effects of cues to action on reducing risky behaviors. These findings extend the HBM by positioning risk awareness as a crucial mediating mechanism and demonstrate that employment status fundamentally shapes how safety cognitions translate into behaviors. The results inform tailored intervention strategies for different rider categories, contributing to more effective safety programs and policies for this high-risk occupational group.
The Load Frequency Control (LFC) challenge in multi-source power systems increasingly complicates with the integration of renewable energy, owing to frequent nonlinearities, uncertainties, and disturbances. Conventional controllers such as proportional-integral-derivative (PID) and adaptive PI–1PD frequently exhibit constraints in terms of stability and convergence speed. This study proposes an optimal fuzzy logic two-degree-of-freedom PID controller (Optimal–FL–2DOF–PID) tuned via a metaheuristic chess optimizer (CO), which is a novel optimization algorithm introduced in this study. The performance was evaluated in MATLAB/Simulink under two scenarios: (i) a 5% Step Load Perturbation (SLP) and (ii) a Random Step Load Pattern (RSLP) increment-decrement that effectively mirrors real-world applications. The simulation results demonstrate that the Optimal–FL–2DOF–PID controller surpasses all the comparable controllers. In Scenario 1, the proposed controller attains the lowest objective function—Integral of Timeweighted Absolute Error (ITAE) of 4.6692 corresponding to reductions of 25.31%, 43.05%, and 41.92% relative to 2DOF–PID, PID, and PI–1PD, respectively (and 1.92% relative to the None–optimal–FL–2DOF– PID), overshoot (OS), undershoot (US), settling time (ST) 13–15 s, and tie-line power deviations are likewise reduced. In Scenario 2, using the corresponding optimum parameters from Scenario 1, the Optimal–FL– 2DOF–PID controller achieves ITAE = 395.72, which is lower than the None–optimal–FL–2DOF–PID controller design by 46.52%, and lower than 2DOF–PID, PID, and PI–1PD by 29.73%, 22.19%, and 9.68%, respectively. The frequency–channel ST is 150–180 s, whereas tie-line exchanges settled in the mid–150 s with visibly smoother profiles. These results indicate that Optimal–FL–2DOF–PID provides robust and efficient frequency regulation for multi-area systems under significant uncertainty, supporting deployment in future renewable energy-integrated power systems.
