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Turkish cashier problem with time windows and its solution by Migrating bird optimization algorithm
No full textA new application of the traveling salesman problem referred to as the Turkish cashier problem (TCP) was recently introduced in literature. The problem revolved around a cashier that must visit several locations and return to his office. To complete his visits, he can use taxis or public transportation and the objective is to minimize the total transportation cost. To make this problem more practical, we took time into consideration by adding a soft time interval for each location obligating the cashier to make his visit within. If he fails to visit within the adequate time, a penalty must be paid. We name this problem as the TCP with time windows (TCPwTW). A metaheuristic algorithm known as the Migrating Birds Optimization (MBO) algorithm coupled with mathematical programming was developed to solve TCPwTW. We attempted to find the exact optimum using an exact solver where for complex problems, optimal solutions cannot be found. The quantitative study reveals that for problems having a loose time interval, the Solver serves as the best approach. On the other hand, for problems having tight time intervals, the best solutions can be obtained by the matheuristic
Automatic detection of attachment style in married couples through conversation analysis
No full textAnalysis of couple interactions using speech processing techniques is an increasingly active multi-disciplinary field that poses challenges such as automatic relationship quality assessment and behavioral coding. Here, we focused on the prediction of individuals’ attachment style using interactions of recently married (1–15 months) couples. For low-level acoustic feature extraction, in addition to the frame-based acoustic features such as mel-frequency cepstral coefficients (MFCCs) and pitch, we used the turn-based i-vector features that are the commonly used in speaker verification systems. Sentiments, positive and negative, of the dialog turns were also automatically generated from transcribed text and used as features. Feature and score fusion algorithms were used for low-level acoustic features and text features. Even though score and feature fusion algorithms performed similar, predictions with score fusion were more consistent when couples have known each other for a longer period of time.TÜBİTA
Design methodology of a concentrating solar volumetric receiver
No full textA volumetric receiver design process is proposed to respond wide range of power, outlet temperature, or mass flow rate needs. In the receiver model, concentrated solar radiation hits the inner surface cavity and heats the gaseous fluid passing through the porous media assembled between the cavity and the insulator. Porous media properties and receiver geometry are coupled in the design process to determine the best possible option. A two-step process starts with a parameter sweep to create a surrogate model. Then, gradient-based design optimization is performed using two different surrogate models to maximize the outlet air temperature for bounded design variables in receiver volume and outer surface temperature constraints. The proposed design process has the advantage of exploring more design options faster using the surrogate model and more accurate results using the base model in the plant-level simulations. The methodology is discussed by comparing the surrogate models and the model validation shows that over 95% accuracy is obtained using both surrogate models. Surrogate-based design optimization is compared as in solution time and the final results are compared with respect to the base receiver model
Properties of kaon at non-zero temperature and baryon chemical potential
No full textWe investigate the spectroscopic properties of the strange particle kaon in the framework of hot and dense QCD. To this end, first, we find the perturbative spectral density, which is connected with both the temperature T and the baryon chemical potential μB . We include the non-perturbative operators as functions of temperature and baryon chemical potential up to mass dimension five. We perform the calculations in momentum space and use the quark propagator in the hot and dense medium. The numerical results at non-zero temperature and baryon chemical potential demonstrate that the mass of the particle rises considerably by increasing the baryon chemical potential at a fixed temperature (for both the zero and non-zero temperatures) up to approximately μB= 0.4 GeV. After this point, it starts to fall by increasing the baryon chemical potential and it apparently vanishes at μB= (1.03–1.15) GeV for finite temperatures: The point of apparent vanishing moves to lower baryon chemical potentials by increasing the temperature. At zero temperature, the mass reaches to roughly a fixed value at higher baryon chemical potentials. On the other hand, the decay constant decreases considerably with respect to baryon chemical potential up to roughly μB= 0.4 GeV, but after this point, it starts to increase in terms of the baryon chemical potential at finite temperatures. At T= 0 , the decay constant reaches to a fixed value at higher chemical potentials, as well. Regarding the dependence on the temperature we observe that, at fixed values of baryon chemical potentials, the mass and decay constant remain roughly unchanged up to T= 50 MeV and T= 70 MeV respectively, but after these points, the mass starts to fall and the decay constant starts to rise up to a critical temperature T= 155 MeV, considerably. It is also seen that the obtained results for the mass and decay constant at T= μB= 0 are in good consistency with the existing experimental data. The observations are consistent with the QCD phase diagram in the T- μB plane.Iran's National Elites Foundatio
Effect of processing parameters on the phase transformation of a high temperature copper-based shape memory alloy
No full textIn the present study, the influence of the processing parameters on the transformation temperatures and microstructural evolution in a copper-based shape memory alloy was investigated. Five times remelting in identical conditions was conducted to investigate the effect of successive remelting on the microstructural and thermal behavior of the alloy. Samples were hot rolled up to 25, 50, 75, and 90% reduction in thickness after heating at 900 °C. It was demonstrated that one-time remelting is required to achieve a target alloy composition. Thermal hysteresis remained almost constant with elevation in the rolling strain imposed. Furthermore, increased rolling reduction led to decreased enthalpy and entropy levels
Double displacement of refugees in the context of the 2023 Turkey-Syria earthquake
No full textThis commentary is based on our observations during our fieldwork in the earthquake region in Turkey that took place in February 6, 2023 in 11 provinces where 49% of the entire Syrian population in Turkey live. In this commentary, we focus on the case of Syrians, who have been subject to what we call double displacement. Syrian refugees who were already displaced due to the war and faced with many problems in establishing a new life in Turkey once again lost their homes and livelihoods due to the earthquake, exposing them to increased risks and vulnerability
Saturated and superheated water vapor condensation on a custom micro-textured surface
No full textCondensation has a great importance for a large number of technologies such as heat exchangers, distillation columns, heat pipes, and thermal management systems. Vapor changes its phase into liquid when it contacts a surface exhibiting a lower temperature than the saturation temperature of the vapor for a given pressure. In most of those cases, systems are designed in order to achieve the phase-change process at saturated conditions over the entire heat transfer area. However, in some devices, there are sections over which prior the actual condensation occurs, the vapor flows at superheated conditions and needs to be cooled down to saturation. Thereby, one can expect that the heat transfer performance is low and the mode of condensation far away from that of saturated vapor. In this work, heat transfer and wetting characteristics during water vapor condensation at saturated and superheated conditions has been experimentally studied over a certain range of pressure and temperature. Two latter parameters were varied from 1.02 to 1.40 bar and 100{circ} mathrm{C} to 125{circ} mathrm{C}. The phase-change phenomenon has been realized on an unstructured reference surface as well as on a hexagonally micro-structured surface which was produced by laser-manufacturing. High-speed imaging technique and high-resolution temperature measurements have been adopted in order to identify the wetting behavior of the liquid on the surface and the heat transfer rate during condensation, respectively. The experiments revealed that vapor condensation on an unstructured surface at saturated conditions follows the trend of the well-known Nusselt theory for film-wise condensation. It is observed that an excess of 40 % larger heat transfer coefficients than those predicted by the Nusselt theory was achieved, and heat transfer coefficients (HTC) decrease with increasing vapor-to-surface temperature difference (T-{V}-Ts) from 4 to 24 K for both, unstructured and the micro-structured surface. In contrast, at comparable operating conditions (1.10 bar), the heat transfer coefficient for superheated (110°C) vapor condensation is remarkably lower than those for saturated vapor (sim 100{circ} mathrm{C}) and describes a considerably distinct trend. The HTC first sharply increases starting at T-{V}-T-{S}=12 mathrm{K} and shows a decreasing gradient up to a T-{V}-T-{S} text{of}22.5 mathrm{K}.Deutsche Forschungsgemeinschaf
Assessment of learning in child–computer interaction research: A semi-systematic literature review
No full textIn this paper, we investigate and map out how learning is assessed in Child–computer interaction (CCI) research. We have conducted a semi-systematic literature review in the CCI community's leading venues: the Interaction Design and Children (IDC) conference and the International Journal of Child–Computer Interaction (IJCCI). This eventually led to 30 publications that use the word stem ‘learn*’ in title, abstract and keywords being included in the corpus. Based on our analysis of these publications, the results demonstrate that there are three main strands of research approaches, namely quantitative, qualitative and mixed-methods, some of which are design-based. The case studies taking a qualitative approach dominate the field whereas the mixed-methods approach remains low in number. Furthermore, the findings showed that basic characteristics of research design and approaches to the assessment of learning are rarely defined, and that assessment of learning is scarcely operationalized. This affects the methodological rigor and possibility of understanding causality of technology interaction in children's learning. It was also found that only a limited number of works include assessment of learning regarding transfer of learning and controlled groups. The main findings from this review describe the current state-of-the art and address the gaps in CCI research in presenting evidence for learning in children as a desired impact. We conclude with suggestions for future avenues for the assessment of learning in CCI
Free space optical communication: An enabling backhaul technology for 6G non-terrestrial networks
No full textThe deployment of non-terrestrial networks (NTNs) is envisioned to achieve global coverage for 6G and beyond. In addition to space nodes, aerial NTN nodes such as high-altitude platform stations (HAPSs) and rotary-wing unmanned aerial vehicles (UAVs) could be deployed, based on the intended coverage and operational altitude requirements. NTN nodes have the potential to support both wireless access and backhauling. While the onboard base station provides wireless access for the end users, the backhauling link connects the airborne/space-borne base station to the core network. With its high data transmission capability comparable to fiber optics and its ability to operate in the interference-free optical spectrum, free space optical (FSO) communication is ideally suited to backhauling requirements in NTNs. In this paper, we present a comprehensive tutorial on airborne FSO backhauling. We first delve into the fundamentals of FSO signal transmission and discuss aspects such as geometrical loss, atmospheric attenuation, turbulence-induced fading, and pointing errors, all of which are critical for determining received signal levels and related link budget calculations. Then, we discuss the requirements of airborne backhaul system architectures, based on use cases. While single-layer backhaul systems are sufficient for providing coverage in rural areas, multi-layer designs are typically required to establish connectivity in urban areas, where line of sight (LoS) links are harder to maintain. We review physical layer design principles for FSO-based airborne links, discussing both intensity modulation/direct detection (IM/DD) and coherent modulation/coherent demodulation (CM/CD). Another critical design criteria for airborne backhauling is self-sustainability, which is further discussed in our paper. We conclude the paper by discussing current challenges and future research directions. In this context, we discuss reconfigurable intelligent surfaces (RIS) and spatial division multiplexing (SDM), for improved performance and an extended transmission range. We emphasize the importance of advanced handover techniques and scalability issues for practical implementation. We also highlight the growing role of artificial intelligence/machine learning (AI/ML) and their potential applications in the design and optimization of future FSO-based NTNs.TÜBİTAKPublisher versio
AhBuNe agent: Winner of the eleventh international automated negotiating agent competition (ANAC 2020)
No full textThe International Automated Negotiating Agent Competition introduces a new challenge each year to facilitate the research on agent-based negotiation and provide a test benchmark. ANAC 2020 addressed the problem of designing effective agents that do not know their users’ complete preferences in addition to their opponent’s negotiation strategy. Accordingly, this paper presents the negotiation strategy of the winner agent called “AhBuNe Agent”. The proposed heuristic-based bidding strategy checks whether it has sufficient orderings to reason about its complete preferences and accordingly decides whether to sacrifice some utility in return for preference elicitation. While making an offer, it uses the most-desired known outcome as a reference and modifies the content of the bid by adopting a concession-based strategy. By analyzing the content of the given ordered bids, the importance ranking of the issues is estimated. As our agent adopts a fixed time-based concession strategy and takes the estimated issue importance ranks into account, it determines to what extent the issues are to be modified. The evaluation results of the ANAC 2020 show that our agent beats the other participating agents in terms of the received individual score