Search Results (21)

Background/Objectives: For runners competing abroad in sports events, the hours before a race are marked by heightened psychological tension, where even food choices can feel crucial to success. While pre-race nutrition is often addressed in terms of physiological needs, little is known about the inner psychological processes that accompany food decisions in unfamiliar cultural and environmental contexts. This study explores the inner dialogues, anxieties, and coping mechanisms of international runners facing the question of whether and what to eat before competition. Methods: A qualitative study was conducted with twelve international participants (from the United Kingdom, Germany, and Ukraine) of the Poznan Half Marathon 2025. Data were collected through semi-structured in-depth interviews. Participants possessed a minimum of two years’ experience competing in international events. Results: Three thematic areas were identified: (1) anticipatory anxiety and fear of making nutritional mistakes before the race, (2) internal negotiation between prior nutritional knowledge and situational trust, and (3) ritualization and individualized norms as fundamental mechanisms of psychological regulation. These themes influenced how runners experienced pre-race nutrition, shaping their emotional states, decision-making processes, and coping strategies in the context of international competition. Conclusions: Pre-race nutrition decisions are deeply embedded in emotional and cognitive landscapes shaped by stress, cultural context, and individual history. Recognizing these inner dynamics can help coaches, sports nutritionists, and event organizers better support the psychological well-being of traveling athletes. Full article

Redemption, as a response to guilt and a path toward self-realization, is a fundamental theme in human narratives. The Kite Runner by Khaled Hosseini poignantly explores this theme through the protagonist’s moral conflict, internal struggle, and eventual journey toward atonement. While prior studies have predominantly examined the novel through psychological and literary lenses, this paper adopts a linguistic perspective by applying van Leeuwen’s Social Actor Network Model within the framework of Critical Discourse Studies (CDS). It investigates how discourse constructs and negotiates guilt, moral responsibility, and redemption through social actor representation, role allocation, and inclusion/exclusion strategies across Amir’s narration, inner monologue, and dialogue. The analysis reveals that linguistic techniques such as association, passivation, and categorization play a pivotal role in shaping the protagonist’s moral transformation. By foregrounding the role of discourse in constructing ethical identity, this study offers a novel contribution to both literary linguistics and trauma narratives. It also adds to global scholarly conversations on how language mediates reconciliation and recovery in postcolonial and transnational fiction. Full article

Kaplan turbines are widely utilized in low-head and large flow power stations. This paper employs Computational Fluid Dynamics (CFD) to complete numerical calculations of the full flow channel under different blade angles and various guide vane openings, based on 25 off-cam experimental working conditions. The internal flow characteristics of the runner blade and draft tube are analyzed, and a discriminant number for quantitatively assessing the flow uniformity of the draft tube is proposed. The results indicate that low-frequency and high-amplitude pressure pulsations occur on the high- and low-pressure edge of the blade when the opening is small, with pulsations decreasing as the opening increases. The inner flow line of the draft tube is disturbed when both the blade angle and opening are small. Additionally, the secondary frequency of the draft tube inlet is double that of the vane passing frequency. The discriminant number of the flow inhomogeneity approaches 0 under optimal flow conditions. The number increases continuously with the decrease in efficiency, and the flow in the three piers of draft tube becomes more nonuniform. The research results provide a reference for enhancing performance and ensuring the operational stability of Kaplan turbines. Full article

In this work, an experimental analysis of the performance of a cross-flow turbine, commonly referred to as a Michell–Banki turbine (MBT), is carried out for small-scale hydropower production in rural areas located in developing countries to support their social and economic development activities. The study investigates how the efficiency of the MBT is influenced by the presence or absence of a nozzle, along with variations in the internal guide vane (GV) and its angle. The runner had 26 blades that were arranged symmetrically in the periphery between two circular plates. The designed MBT had the ability to generate a maximum of 100 W of power at a water flow rate and a head of 0.009 m³/s and 0.6311 m, respectively. The experimental tests were carried out using a hydraulic bench. The turbine efficiency without the inner GV was found to be higher than that of the turbine with the inner GV; i.e., it was found that the utilization of the GV did not enhance the efficiency of the MBT due to the occurrence of a choking effect. A maximum hydraulic efficiency of 85% was achieved in the turbine without an inner GV in comparison with the efficiency achieved (77%) with this device and an optimum opening angle of the GV of 24° (75% of opening). In this regard, the GV design should be carefully carried out to improve the MBT efficiency. Additionally, the effect of the GV shape on the MBT performance should be experimentally investigated to obtain a more general judgment regarding the role of this device. Full article

Three-dimensional printing has great advantages in manufacturing parts with complex internal structures. At present, there are still significant challenges in the unsupported 3D printing of thick-walled parts with inner runners. In this paper, a partitioning method for support-free-fabricating workparts with a built-in inner runner structure is proposed and discussed in detail. With the method, partitioning planes are firstly created according to the direction changes of the inner runner, a “top to bottom” method is used for avoiding the interference of the generated planes, and thirdly the outer surface of the workpiece is considered for a second partition for the support-free purpose. A key algorithm for calculating partitioning planes for inner runner structures is also proposed and introduced in detail, including the iteration method, the calculation for intersectional profile mass centers, and the discussion of the convergence. Algorithm analysis is also performed with a simple model for assessing the influence from the defined parameters, including the proximity Φ_s and the increment coefficient σ, on the iteration results as well as on the iteration process. Also, an application test is carried out on a column model with a complex inner runner structure built-in. The result from all the tests indicates that the proposed algorithm is successful in partitioning inner runner structures for support-free fabrication. Full article

During the operation of pumped storage power stations, complex operating conditions can lead to different internal flow characteristics, which can cause different vibration characteristics or even damage to the structural components of the pump-turbine units. The time–frequency characteristics of the structural components’ response are of great significance for the safe operation of the unit. In this study, a three-dimensional flow field and structural field model of a large high head prototype pump-turbine is built in order to study the flow and the flow-induced dynamic response characteristics in different turbine operating conditions. The analyzed results show that the maximum deformation occurs at the inner head cover, and the maximum value of stress is located at the fillets on the outlet side of the stay vanes. Under the 50% load condition, the vortices in the runner caused by changes in the opening of the guide vanes result in the main response frequency of 4 $f_n$ of the stationary components. The research results can provide references for the structural optimization design of other pump-turbine units. Full article

To study the influence of the axial installation deviation of the runner on the hydraulic axial force of the 1000 MW Francis turbine unit, geometric models of the full flow passage of the Francis turbine with the runner sinking in the axial direction by 0, 0.5, 1, 1.5, 2.5, 4, and 5.5 mm were established. The geometric models of the upper crown clearance, lower band clearance, and pressure balance pipes were also built. The SST turbulence model was used in the CFD setup to numerically simulate the flow in the Francis turbine with different runner installation sinking values. The results show that the hydraulic axial force on the inner surface of the runner remains stable when the runner is lowered. The hydraulic axial force on the entire runner surface and the outer surface of the lower band decreases, and the hydraulic axial force on the outer surface of the upper crown clearance increases. All of these hydraulic axial forces gradually tend to stabilize as the amount descending from the runner increases. To study the reasons for the changes in hydraulic axial forces, the streamlines and fluid fields of different sections in the flow passage were analyzed in detail. It was found that periodic changes of vortices were generated in the clearance due to the influences of the geometric shape and wall rotation. These vortices affect the distribution of velocity and pressure and, thus, determine the hydraulic axial forces. The runner axial installation deviation has little influence on the streamlines, pressure, and velocity distribution in each flow passage, and only changes the velocity and pressure in the upper crown clearance and lower band clearance. Therefore, the axial installation deviation of the runner has a great effect on the hydraulic axial force on the outer surface of the upper crown and lower band and has a smaller impact on the runner passage and the hydraulic axial force on the inner surface of the runner. The conclusions in this study can be adopted as references for the installation accuracy control of other hydraulic Francis turbine units. Full article

The current study investigated the determinants of the desire and intention to participate in an inner-city ‘running crew’ among social runners using a theoretical framework of the model of goal-directed behavior (MGB). Data were obtained from 245 social runners in Korea using an online questionnaire and primarily analyzed with the structural equation modeling technique. The results indicated that the desire to participate in a running crew was influenced most by positive anticipated emotions, followed (in descending order) by attitudes, negative anticipated emotions, social norms, perceived behavioral control, and the frequency of past behaviors. Runners’ behavioral intentions were predicted by desire but not directly related to perceived behavioral control and the frequency of past behavior. Overall, the study emphasized the importance of positive anticipated emotions and behavioral desire, among others, to encourage recreational runners’ participation in social running activities. Given that social runners rely on mobile apps to participate in running crew activities, the current study’s results have practical implications for running crew organizers, sports-branded app developers, and health promotion agencies. Full article

In order to ensure stable grid operatiFon and improve power quality, active or passive load rejection of pumped storage power stations (PSPS) inevitably occurs from time to time. The rapid closing of the guide vanes will cause drastic changes in pressure pulsations in the flow channel of the pump-turbine (PT) unit. The high-level pressure pulsations during load rejection transfer to the entire flow passage of the PT unit and generate strong vibrations on the head-cover and the connecting bolts. In this study, the 1D/3D joint simulation of the pipeline in a pumped storage power station and the turbine flow channels including the flow domains of the runner, crown chamber, band chamber, upper and lower labyrinths and pressure balance tubes is carried out first. Then, by applying the calculated pressure loads on the head-cover, stay vanes and bottom ring of the PT unit, the flow-induced dynamic behavior of the structures including the head-cover bolts is analyzed in detail. The results demonstrate that pressure loads on head-cover bolts change dramatically during the load rejection process. The flow-induced deformation of the inner head-cover during the load rejection is larger than that of other structures, and the flow-induced displacement and stress of different head-cover bolts are not uniform. The achieved conclusions in this study can be a useful reference for the design and operation of head-cover bolts for other PT units and high-head Francis turbine units. Full article

Pumped storage-power plants play an extremely important role in the modern smart grid due to their irreplaceable advantages in load peak-valley regulation, frequency modulation, and phase modulation. The number of start-stops per day of pump-turbine units is therefore also increasing. During the start-up transient process in turbine mode, the complex flow in runner passage, crown and band chambers, and seal labyrinth is able to induce severe vibration of non-rotating structures such as head cover, stay-ring, and pose a threat to the safe operation of the pump-turbine unit. In this article, the flow-induced vibration of the structures of a pump-turbine unit during its start-up process in turbine mode is studied. In the first place, this investigation establishes a three-dimensional model of the full flow passage and carries out a full three-dimensional CFD calculation based on one-dimensional pipeline calculation results for the start-up transient process. In the next place, by applying the fluid–structure interaction calculation method, the finite element analysis of non-rotating components of the pump-turbine unit is carried out. The flow-induced stresses and deformations of head cover, stay-ring, etc., are obtained and analyzed. The results reveal that the maximum deformation of the non-rotating structures is located at the inner edge of the head cover while the maximum stress appears at the trailing edge fillet of a stay vane. In summary, the dynamic stress of the non-rotating structures changes largely during the start-up process. The stress is strongly related to the axial thrust caused by the fluid flow. The achieved results can provide guidance for further fatigue life assessment of non-rotating structures and contribute to the structural safety design of pump-turbine units. Full article

The effect of the cast process procedure and pouring systems on several typical metallurgical defects for TiAl case casting was studied by numerical simulation and pouring test. The results indicated that gravity casting had much better melt-filling stability and synchronization, compared to centrifugal casting. Misrun defects in the upper edge of the thin-walled outer ring could be removed by increasing the bottom cross runners, and the negative effect of the overheated zone in the thick-walled flange could be reduced by designing a suitable inner-gate structure. The crack induced by stress concentration in the transition zone brought significant challenges for TiAl case casting and the issue would be effectively resolved through structural design and process optimization. Full article

Social change and development influence the motivational factors of people’s sports participation, exposing the need for socialization and interaction. The purpose of this study is to investigate the interaction pattern of the urban running community and the behavior pattern of runners with the help of social interaction theory, and to explore the inner connection between their community movement and social interaction. Ten senior members of marathon urban running societies were selected to conduct two rounds of in-depth interviews which were analyzed using qualitative thematic analysis to understand the sports participation experiences and social interactions of running society members. The study found that the whole interaction process of running groups is accomplished through three aspects: examination of self, adjustment with reference to others, and a sense of group belonging as the core consciousness. On the other hand, the social attributes of running groups can advance the personalization process of runners in society, which is mainly characterized by self-presentation and external constraints, self-requirement and group constraints, intergroup interaction and group identity reorganization. In addition, the unique community culture, standardized group organization and harmonious activity atmosphere will stimulate runners’ interest in running, strengthen community communication and establish stable community relations, etc., which in turn will bring about continuous interactive behaviors. Full article

Running can promote public health. However, the association between running and the built environment, especially in terms of micro street-level factors, has rarely been studied. This study explored the influence of built environments at different scales on running in Inner London. The 5Ds framework (density, diversity, design, destination accessibility, and distance to transit) was used to classify the macro-scale features, and computer vision (CV) and deep learning (DL) were used to measure the micro-scale features. We extracted the accumulated GPS running data of 40,290 sample points from Strava. The spatial autoregressive combined (SAC) model revealed the spatial autocorrelation effect. The result showed that, for macro-scale features: (1) running occurs more frequently on trunk, primary, secondary, and tertiary roads, cycleways, and footways, but runners choose tracks, paths, pedestrian streets, and service streets relatively less; (2) safety, larger open space areas, and longer street lengths promote running; (3) streets with higher accessibility might attract runners (according to a spatial syntactic analysis); and (4) higher job density, POI entropy, canopy density, and high levels of PM 2.5 might impede running. For micro-scale features: (1) wider roads (especially sidewalks), more streetlights, trees, higher sky openness, and proximity to mountains and water facilitate running; and (2) more architectural interfaces, fences, and plants with low branching points might hinder running. The results revealed the linkages between built environments (on the macro- and micro-scale) and running in Inner London, which can provide practical suggestions for creating running-friendly cities. Full article

Accurate forecasts of the properties of interplanetary coronal mass ejections (ICMEs) prior to their arrival at Earth are unquestionably a key goal for space weather. Currently, there are several promising techniques for accomplishing this, including the more focused but limited objective of predicting the time of arrival (ToA) of the ICME at Earth. In this study, we describe a new tool, sunRunner1D, with the initial goal of being able to reproduce the structure and evolution of four categories of CMEs as they propagate from the corona to 1 AU. We demonstrate that sunRunner1D can reproduce the essential properties of these ICMEs to varying degrees of success. We suggest that, ultimately, this tool could assist operational forecasters in predicting space weather events, and their associated geomagnetic consequences. In the nearer term, we anticipate that it could potentially provide useful forecasts for ToA. Full article

During the load rejection transient process of the prototype pump turbine units, the pressure fluctuations of the entire flow passage change drastically due to the rapid closing of guide vanes. The extremely unsteady pressure distribution in the flow domains including the crown chamber and the band chamber may cause a strong vibration on the stationary structures of the unit and result in large dynamic stress on the head cover, stay ring and bottom ring. In this paper, the numerical fluid dynamic analysis of the entire flow passage of a reversible prototype pump turbine during load rejection was performed. The flow characteristics in the runner passage, crown chamber, band chamber, seal labyrinths and balance tubes are analysed. The corresponding unsteady flow-induced dynamic behaviour of the head cover, stay vanes and bottom ring was investigated in detail. The analysed results show that the total deformation of the inner edge of the head cover closed to the main shaft is larger than that of other stationary structures of the unit during the load rejection. The maximum stress of the stay ring is larger than that of the head cover and the bottom ring and the maximum equivalent stress is located at the fillet of the stay vane trailing edge. The fluid–structure coupling calculation method and the analysed results can provide guidance for the design of stationary components of hydraulic machinery such as pump turbines, Francis turbines and centrifugal pumps with different heads. Full article