https://hdl.handle.net/20.500.12960/17 2026-05-11T12:26:38Z https://hdl.handle.net/20.500.12960/1824 Modeling Gradual and Joint Coverage in Location Problems Karatas, Mumtaz; Eriskin, Levent; Yakici, Ertan Location problems are a core area of research within OR/MS and decision sciences, with diverse applications in logistics, facility location, healthcare, defense, energy and transportation. One important feature of location problems is the coverage of demand or service areas by facilities, which can have significant economic, social, and environmental implications. Conventional models often assume binary or deterministic coverage, where a facility either fully covers a demand point or does not cover it at all. Although this simplification is useful for theoretical derivations, back-of-the-envelope calculations, and performance comparison, it overlooks the nuances and complexities of real-world scenarios. In this study, we provide an overview of the modeling challenges in location problems that incorporate gradual and joint coverage, where multiple facilities provide partial and cooperative coverage to demand points. Based on previous studies in this domain, we present mathematical formulations, and discuss techniques for linearization and approximation. As an illustrative example, we discuss a capacitated minimal covering location problem (MCLP) adapted from [21], which aims to determine the location and size of undesirable facilities in a given region. We start by introducing the nonlinear formulation that minimizes the sum of demand covered by those undesirable facilities. Subsequently, we introduce three integer linear programming formulations given in [21], two of which involve linear approximations based on a separable programming approach and a tangent line approximation method, while the third involves an exact reformulation of the problem. We also discuss the impact of linearization approximation errors on solution quality and time. © 2026 by World Scientific Publishing Co. 2025-01-01T00:00:00Z https://hdl.handle.net/20.500.12960/1822 Comprehensive first-principles studies of structural, dynamical, elastic, electronic, thermoelectric, and thermodynamic properties of Half-Heusler TiGaAu compound Belbachir, Raghed; Belkharroubi, Fadila; Al-Douri Y.; Sidjilani, Fatima; Khelfaoui, Friha; Azzi, Saliha; Belmiloud, Nawal; Rahmani, Rabea; El Hadj, Adel Abdellah; Bendella, Sid Ahmed The structural, elastic, electronic, dynamical, thermoelectric (TE), and thermodynamic properties of Half-Heusler (HH) TiGaAu compound with valence electron count (VEC) of 8, are investigated usingfirst-principles density functional theory (DFT) in conjunction with Boltz- TraP2 transport modeling. The Type 1 nonmagnetic phase's optimized cubic structure meets the Born mechanical stability requirements and its dynamical stability, which is confirmed by the phonon dispersion's lack of imaginary frequencies. Due to the presence of a heavy Au atom, TiGaAu exhibits pronounced elastic anisotropy and is mechanically strong, stiff, and ductile according to elastic constants. With a moderate band gap, 0.681 eV (mBJ-GGA), the electronic band structure favors balanced electron{hole transport and reveals an indirect semiconductor character. Thermoelectric analysis reveals that TiGaAu has competitive values up to 900K and high Seebeck coeffcients exceeding 1000 μVK-1 at room temperature, with p-type carriers performing marginally better. Effective carrier transport and advantageous band convergence are reflected in the power factor's steady temperature increase. Though mBJ-GGA predicts somewhat higher Seebeck and power factor values at higher temperatures - an improvement ascribed to its more accurate description of electronic structure - the results obtained using GGA and mBJ-GGA are consistent across the whole range. Furthermore, an excellent thermal stability and moderate lattice softening are confirmed by the smooth variation of temperatureand pressure-dependent thermodynamic properties, including heat capacities, entropy, thermal expansion coeffcient, Debye temperature and Grüneisen parameter. TiGaAu is a promising option for high-temperature energy conversion applications as it combines a strong mechanical resilience, stable lattice dynamics and effcient thermoelectric behavior. 2026-01-01T00:00:00Z https://hdl.handle.net/20.500.12960/1819 A review on recent developments in electrospun polymeric nanofibers for oil–water separation Zembat, Ahmet Alp; Cansoy, C Elif Oil–water separation is an important process used to reduce pollution and recover valuable resources in many industrial applications. Electropun nanofibers with varying chemical composition and dimensions are commonly used to remove pollutants from water. Various nanoadditives, such as clays, metal nanoparticles, and C-based nanoparticles, can also be introduced into the polymeric nanofiber matrix to improve the removal capacity and flux of the prepared membranes. Various studies in the literature have investigated the use of these polymeric nanofibers in the separation of oil–water mixtures and oil–water emissions, and very good separation efficiencies have been supported by experimental studies. This review briefly summarises the recent developments on polymeric nanofibres used in oil–water separation. The reviewed studies showed that wettability, fiber diameter, chemical structure, and composition of the nanofibers are important parameters for the removal of contaminants, and polymeric nanofibers produced by tailoring their chemical composition and dimensions are promising candidates for many oil–water separation applications. 2026-01-01T00:00:00Z https://hdl.handle.net/20.500.12960/1817 Evaluation of using different metals and working fluids on the thermal performance of nano heat pipes Huang, He; Dheyaa, J. Jasim; Sawaran Singh, Narinderjit Singh; Ahmad, Nafis; Saydaxmetova, Shaxnoza; Smerat, Aseel; Salahshour, Soheil; Sajadi, S. Mohammad; Emami, N. The precise and effective management of heat produced by micro-scale devices, such as electronic processors, is of utmost importance. Heat pipes (HPs) are among the instruments utilized for this objective. The incorporation of nanofluids can significantly improve the thermal performance of HPs at smaller scales. This study examines the impact of spherical nanoparticles on the working fluid of a micro flat-plate HP. A variety of metals and working fluids were utilized, and molecular dynamics (MD) simulations were performed. The findings indicate that, for any specified nanoparticle volume fraction (φ), the highest and lowest evaporation rates correspond to EtOH and H2O, respectively. Platinum (Pt) and aluminum (Al) exhibit the lowest and highest evaporation rates, respectively. In general, an increase in φ leads to enhancements in both mass transfer and heat flux. The maximum condensation rate (79%) is achieved with Cu-EtOH at φ = 1.05, while the minimum (65%) is observed with Pt-H2O at φ = 0.35. The highest mass transfer rate (40%) is recorded for AlAr at φ = 1.05, whereas the lowest (26%) is noted for Pt-H2O at φ = 0.35. The minimum heat flux (1613 W/cm2) is associated with Pt-EtOH, while the maximum (2092 W/cm2) is linked to Cu-H2O. The body material and the working fluid play a crucial role in determining the heat flux within the HP. 2026-01-01T00:00:00Z