印度理工学院

Y1−xCexMnO3 (x = 0.0, 0.05, 0.10) manganites, were investigated to correlate structural distortion, defect chemistry, and multifunctional properties. Rietveld-refinement confirms the retention of the hexagonal P63cm structure upon Ce doping, accompanied by anisotropic lattice distortion, increased crystallite size, and microstrain. XPS indicates the coexistence of Ce3+/Ce4+ and Mn3+/Mn4+ mixed-valence states along with oxygen vacancies. Optical band gap reduced from 1.42 to 1.36 eV with increasing Ce content, suggesting defect-induced band tailing. Magnetic measurements reveal a suppression of the Néel temperature from ∼72 K to 56 K, which indicates short-range ferromagnetic correlations. Curie-Weiss analysis demonstrates a reduction in antiferromagnetic interaction and magnetic frustration, confirming a transition toward a magnetically inhomogeneous state. Isothermal magnetization supports the coexistence of competing antiferromagnetic superexchange and ferromagnetic double-exchange interactions. Bound magnetic polaron analysis suggests defect-mediated magnetic clustering upon Ce substitution. Moreover, 10% Ce doped YMnO3, achieving ∼79% methylene blue degradation within 180 min compared to ∼45% for YMnO3. These results provide important insights into the development of advanced oxide materials for optoelectronic and water remediation applications.

Abstract Double-skin tubular columns (DSTCs), composed of two concentrically placed hollow steel tubes with sandwiched concrete infill, are efficient composite sections for resisting high axial loads. However, localized buckling failure of the steel tube restricts its structural efficiency. Multicell DSTCs (MCDCs), incorporating stiffeners between the tubes, improve confinement and ductility, but existing confinement models fail to accurately capture stiffener-induced effects and are constrained by limited experimental evidence. This study introduces a modified confinement model that explicitly accounts for the enhanced confinement provided by the stiffeners, representing a significant advancement over previous models. The model is validated through nonlinear finite-element analysis and experimental comparisons, demonstrating an excellent accuracy ( R 2 = 0.99 and average error < 5 % ). A comprehensive parametric study is also conducted, covering the stiffener number, distribution, and hollowness ratio across a wide range. The findings reveal the governing parameters controlling the axial strength and failure modes and highlight the limitations of existing axial strength prediction models. By addressing gaps in the past research and providing a more comprehensive design methodology, this work provides new insights and an analytical framework for optimizing the structural performance of MCDCs in structural engineering applications.

Abstract Biobinders are increasingly gaining attention in the pavement community as sustainable alternatives to conventional petroleum-derived asphalt binders. While complete replacement of asphalt binder remains challenging, growing environmental concerns and energy crises demand at least partial substitution with renewable and ecofriendly materials. In this context, this study explores the use of pomegranate molasses (PM), a natural biobased product, as a novel asphalt binder modifier. A comprehensive experimental program was conducted to evaluate the chemical, thermal, rheological, and mechanical effects of PM incorporation at three dosages (10%, 20%, and 30% by weight of asphalt binder) compared with a reference binder. Fourier transform infrared spectroscopy confirmed the presence of oxygenated functional groups (O─H, C═O, S═O) introduced by PM, while thermogravimetric analysis showed that the modifier is thermally stable under asphalt mixing and compaction temperatures. Binder-level testing revealed improved viscosity and high-temperature performance with PM addition, along with enhanced fatigue life at moderate dosages. At the mixture level, Marshall stability increased by about 11%, wheel-tracking results showed up to a 45% reduction in rut depth, and cracking resistance evaluated through the asphalt flexibility ratio improved at PM10% and PM20% before declining at PM30%. The tensile strength ratio (TSR) remained above the 80% threshold for all mixes, while the resilient modulus increased with PM content. One-way ANOVA confirmed that PM had a statistically significant effect on rutting resistance ( p - value = 0.011 ) but no significant effect on fatigue, TSR, or stiffness. Overall, PM demonstrated strong potential as a sustainable biomodifier, with 20% PM (by weight of the asphalt binder) identified as the optimum dosage, offering the best balance of resistance to rutting, fatigue, cracking, and moisture damage. Further field validation is required to translate these laboratory findings into practical applications.

Abstract In recent years, a significant amount of experimentation has been conducted to evaluate the shear behavior of ultra-high performance concrete (UHPC) flexural members. Several codal procedures, including Swiss society of engineers and architects (SIA) 2052:2016, French national standard (NF)-P18:2016, Korean ultra-high performance concrete (K-UHPC) 2014, China Association for Engineering Construction Standardization (CECS) 38:2004, e.construct prestressed concrete institute (eCPCI) 2021, and federal highway administration (FHWA) 2023, have also been devised to predict the shear capacity of UHPC flexural members. In this study, a qualified database of shear test results was extracted to estimate the statistics of the modeling error defined as the ratio of experimentally obtained shear capacity and shear capacity predicted using design procedures from different codal provisions available for UHPC. Initially, conversion factors for compressive strength among different geometries were established based on the available data to ensure the application of compressive strength of a specific specimen geometry for a particular design procedure. Subsequently, the test data were critically reviewed, and criteria were developed to achieve a reliable database. The refined database comprised 119 test specimens that exhibited shear-dominated failure. However, experimentally obtained tensile properties and shear crack inclination angles, essential for the evaluation of various shear design provisions, were available for only 85 tests. For each shear design method, the modeling error was quantified, and its statistical parameters—mean and coefficient of variation—were computed to assess accuracy and consistency. These results can be used to perform a reliability-based evaluation of structures designed according to the codal provisions, which can be a baseline for reliability-based calibration.

Abstract In this study, the modified reconstructive method of characteristics (RMOC) is used to detect multiple leaks in a pipeline and a branched system using transient data. This approach offers a distinct advantage as it requires measurements at a single location in each pipe. The primary contributions of this research are outlined as follows: (1) the development of RMOC for the detection of multiple leaks in elastic pipes, (2) extension of the method to accommodate viscoelastic (VE) pipes, (3) elimination of the need for prior knowledge of upstream boundary conditions, and (4) development of a stepwise methodology for multiple leak detection in a branched pipe system. By analyzing steady-state (SS) flow discharge within the pipe system, it becomes possible to identify the leaks. The pipeline is discretized into finite cells, and characteristic equations are employed to retroactively calculate steady-state flow parameters. To validate the effectiveness of this methodology, the obtained results are compared with numerical and experimental transient data available in existing literature. To demonstrate the efficacy of the proposed technique in a network, a hypothetical branched pipe system in a Y-configuration is considered, featuring four simultaneous leaks. The leaks are identified sequentially within each section of the Y-system, achieving an acceptable degree of accuracy in detection.