Conventional multiple-jet impingement cooling can provide high local heat transfer, yet under confined conditions its effectiveness is often limited by localized cooling footprints, non-uniform temperature fields, and complex jet-to-jet interference. To address this limitation, the present study numerically investigates the effects of inward-focused jet orientation and jet-to-jet spacing on the flow and thermal characteristics of a confined three-jet impingement system. Three configurations are considered: a baseline vertical arrangement, symmetric inward-focused arrangements, and mixed vertical-inclined arrangements. Simulations are performed for jet spacings of 8, 10, and 12 mm using the SST k-omega turbulence model. The results show that inward focusing improves cooling through momentum exchange and redirection, whereby part of the incoming axial jet momentum is converted into wall-parallel motion before and immediately after impingement. This mechanism broadens the cooled footprint, enhances lateral surface sweeping, and strengthens thermal boundary-layer disruption relative to the vertical baseline. The symmetric inward-focused cases show the clearest and most consistent improvement over the baseline, with the 45 degrees, 225 degrees configuration providing the most robust symmetric performance at 8 and 10 mm, while the 67.5 degrees, 247.5 degrees arrangement becomes particularly attractive at 12 mm. These balanced inwardfocused cases improve heat transfer while maintaining better thermal uniformity than strongly asymmetric arrangements. Although the mixed 90 degrees, 202.5 degrees configuration yields the best overall average thermal performance, the mixed 90 degrees, 247.5 degrees case demonstrates the penalty associated with excessive asymmetry. Overall, the study identifies moderate and balanced inward focusing as a promising strategy for compact, thermally uniform, and high-performance impingement cooling systems.
Abstract International modular construction can improve quality, schedule performance, and labor efficiency, but its supply chains are exposed to cross-border barriers that remain insufficiently understood as an integrated construction-management problem. Existing barrier studies are useful for identifying salient constraints, yet they provide limited insight into how barriers interact and propagate across international modular delivery systems. This study investigates these interrelationships in international modular construction supply chains using a hierarchical grey decision-making trial and evaluation laboratory (G-DEMATEL) framework. Based on literature review, contextual analysis, and expert consultation, 26 barriers were identified and organized into four categories. The framework integrates grey linguistic assessments to capture uncertainty in expert judgments, objective expert-weighting schemes based on certainty and consensus, and hierarchical reconstruction of the global interaction matrix to reduce elicitation burden while preserving systemic interdependence. The results show that supply chain, production reliability, and skills barriers constitute the most prominent category, whereas international regulatory and financial barriers exhibit the strongest causal role. At the global level, Incoterms and risk-transfer ambiguity, shipment-classification ambiguity, and uncertain customs-clearance time emerged as the most prominent barriers, while fragmented regulations and jurisdiction across countries acted as the strongest upstream causal driver. These findings indicate that visible operational disruptions are often downstream effects of upstream regulatory, commercial, and governance uncertainty. The study contributes by explaining barrier propagation in international modular delivery as a cross-border engineering-management system and by providing a scalable decision-support approach for prioritizing earlier interventions related to contracting clarity, customs readiness, coordination, and logistics planning.
This work investigates a simple step-stress accelerated life testing plan based on progressive Type-II censoring for units whose lifetimes follow the TDUSW distribution. The cumulative exposure model is adopted to describe the effect of changing stress levels during the experiment. In this framework, the probability density function and the cumulative distribution function of the TDUSW distribution are incorporated into the likelihood structure of the progressively censored sample. Maximum likelihood estimators of the distribution parameters are derived, and numerical procedures are suggested to obtain their estimates. In addition, the asymptotic variance–covariance matrix is computed via the observed Fisher information. Real data sets and a simulation study are presented to illustrate the performance of the estimators under various censoring schemes. The results demonstrate that the TDUSW model provides a flexible structure for modeling accelerated life-testing data and yields stable parameter estimates even under moderate censoring.
Thin film flows of yield-stress fluids on partially slip surfaces are relevant to many technological and biomedical applications, including industrial coatings and blood flow in vessels. In this paper, we study the effect of Casson-type viscoplastic rheology and Navier-slip boundary conditions on the stability of gravity-driven film flows, an area that has received little attention. A detailed stability analysis is performed for a Casson fluid film flowing down a slippery inclined plane. The Orr-Sommerfeld equation is derived for linear instability analysis, which gives the critical conditions for the onset of instability. A nonlinear evolution equation for the free surface behavior is derived by the long-wave expansion method. Linear and nonlinear instabilities are studied, including temporal and spatiotemporal instabilities with a normal mode approach. The results are in agreement with the linear instability results obtained in the Orr-Sommerfeld analysis and the long-wave approximation. Applying the method of multiple scales, a Ginzburg-Landau-type equation is obtained, and it is proved that the slip length parameter destabilizes the system, influenced by the Casson fluid parameter and the critical Reynolds number. A spatiotemporal stability analysis categorizes the unstable regimes as absolute or convective through a dimensionless dispersion relation. Multi-scale methods investigate the weakly nonlinear stability of the thin film flow and lead to a complex Ginzburg-Landau equation, delineating four instability zones: supercritical, subcritical, unconditional stability, and explosive zones, guided by coefficient sign functions in the CGLE. Stability maps provide quantitative guidelines for achieving uniform coatings and predicting flow transitions in biomedical devices with yield stress and interfacial slip. The wave amplitudes and phase speeds depend on the Casson fluid parameter and slip length, and the traveling wave solutions verify the fixed points in the parametric space. The study also shows that the Hopf bifurcation at these fixed points increases with slip length and decreases with Casson fluid parameter. The numerical investigation of the nonlinear Benney equation reveals distinct supercritical and subcritical wave regimes, highlighting the contrasting effects of slip length γ and Casson fluid parameter β on the nonlinear dynamics of thin liquid films.
Water pollution and shortages are critical global challenges, and the green synthesis of nanomaterials provides a sustainable solution for water purification, targeting the removal of dyes, heavy metals, and bacteria. Utilizing agricultural waste (e.g., cladosiphon, bamboo, cane stalks), this approach offers eco-friendly, cost-effective alternatives to conventional methods. Recent advancements in green synthesis techniques have led to the development of carbon-based nanomaterials like carbon dots, quantum dots, nanofibers, nanotubes, and metal oxides such as ZnO, TiO2, and IONPs. A bibliometric analysis of 270 relevant articles (2015-2024) reveals a significant rise in publications, peaking at 57 articles in 2023, with India leading the field with 89 publications. CVarious methods have shown impressive pollution reduction: CNTs at 0.05 g/L removed 99.8% of Methylene Blue (MB), while TiO2 eliminated 100% of RR250 dye in 60 min. Green-synthesized nanomaterials, like iron and silver, also demonstrate potential, with iron nanoparticles achieving 100% Cr (VI) removal and silver from Acacia ehrenbergiana reducing RhB dye by 96%. This review emphasizes the novelty of hybrid synthesis methods that combine green chemistry with traditional techniques, offering a useful solution for addressing challenges in scalability. By integrating these approaches, the potential of green-synthesized nanomaterials for large-scale water treatment is significantly enhanced. Future studies will focus on optimising these synthesis processes through AI-driven techniques and incorporating life cycle assessments (LCA) to evaluate the long-term environmental impact and commercial feasibility of these materials, ensuring their broader applicability and sustainability.
