Search results

High head gates are commonly used in hydropower plants for flow regulation and emergence closure. Hydrodynamic downpull can be a critical parameter in design of the lifting mechanism. The purpose of this paper is to show that a simplified two-dimensional (2D) computational fluid dynamics solution can be used in the prediction of the downpull force on the gate lip by comparison of computed results to experimentally measured data.

In this study, ANSYS FLUENT CFD software was used to obtain 2D numerical solution for the flow field around a generic gate model located in a power intake structure which was previously used in an experimental study. Description of the flow domain, computational grid resolution, requirements on setting appropriate boundary conditions and methodology in describing downpull coefficient are discussed. Total number of 245 simulations for variable gate lip geometry and gate openings were run. The downpull coefficient evaluated from the computed pressure field as function of gate opening and lip angle are compared with the experimental results.

The computed downpull coefficient agrees well with the previous experimental results, except one gate with small lip angle where a separation bubble forms along the lip, which is responsible from this deviation. It is observed that three-dimensional (3D) effects are confined to the large gate openings where downpull is minimum or even reversed.

In large gate openings, three dimensionality of the flow around gate slots plays an important role and departure from 2D solutions become more pronounced. In that case, one might need to perform a 3D solution instead.

This paper presents a very fast and accurate way to predict downpull force on high head gates in the absence of experimental data.

An extensive amount of simulations are run within the scope of this study. It is shown that knowing its limitations, 2D numerical models can be used to calculate downpull for a wide range of gate openings without the need of expensive experimental models.

While the number of tourists worldwide is expected to reach 1.8 billion people by 2030, tourism destinations try to meet demand for increasing tourism. However, some tourism destinations are experiencing a maturity period of destination life cycle intensively. During these mature periods, while they meet the demand above their tourism carrying capacity, they encounter some problematic issues. In tourist destinations such as Venice, Barcelona and Paris, the negative feelings developed by the local people towards overtourism or tourists result in serious problems like negative destination images, tourism phobia, etc. In these destinations, to prevent the negative consequences of overtourism, destination stakeholders should develop solutions to these problems. There are many solution techniques for the problems which cause overtourism. One of them is the different tourism types which have been developed as an alternative to mass tourism. These alternative tourism types can be handled as a method for solving problems revealed through excess demand in tourism destinations at risk. For example, some tourism destinations which have both beach tourism and nature-based tourism types can bring nature-based tourism activities to the forefront with promotion and marketing activities and therefore, the tourism demand could be balanced between these tourism types. In this context, firstly, comprehensive literature review of overtourism and alternative tourism will be conducted in this study. And then the different types of tourism such as ecotourism, cultural tourism and responsible tourism will be discussed in detail and their relation in reducing the negative consequences of overtourism will be investigated theoretically via secondary data. Therefore, alternative tourism potentials will be investigated and tried to present the managerial suggestions for the development of different alternative types of tourism. As a result, it has been seen that, alternative tourism not only contributes to the growth of tourism in both popular and remote destinations but also makes sure that destinations get their fair share in income distribution of the country.

Under the current Coronavirus Disease 2019 (COVID-19) pandemic circumstances where the gold prices are increasing and the stocks are in free fall, this research aims to compare the returns of gold prices and Turkish real estate investment trust (T-REIT) index by covering the 2008 global financial crisis, 2018 Turkish currency crisis and 2020 COVID-19 pandemic-based economic crisis periods and examine the effects of the returns of gold and the T-REIT index on each other, a research area that has been limited in the literature.

For the empirical analysis, vector auto regression model was used, and Augmented Dickey–Fuller and Granger causality tests were also conducted. The average returns were compared with the coefficient of variation analysis.

The results of the study exhibited that except for the 2008 global financial crisis period, 2018 Turkish currency crisis and 2020 COVID-19 pandemic-based economic crisis, the T-REIT index performs better than gold prices, but it is a riskier instrument, and both investment instruments do not affect the returns of each other. The segmentation of both instruments recommends the fund managers including both tools for diversification of a portfolio.

In Turkey, gold prices are valued based on the fluctuations of the global gold prices, as well as the Turkish Lira/US Dollar currency exchange rates. The effect of the exchange rates may be considered in future studies, and the study may be conducted based on the USD values of the T-REIT index and global gold prices. Further studies may also include the comparison between the T-REIT index returns and a set of commodities such as the Goldman Sachs Commodity Index. This study covered only the first five months of 2020 to analyze the COVID-19 pandemic-based economic crisis initial effects, and a successor study is also recommended by including more new data of the post-COVID-19 pandemic and comparing both results.

The results of the research are expected to contribute to the REIT literature and give insight to investors about their investment choices while including both investment tools in their portfolio, especially for the future conditions of the new COVID-19 pandemic-based economic crisis.

The study may provide insight for individuals, especially those who are considering possible investment options in the Turkish real estate market in the post-COVID-19 pandemic crisis.

Gold and real estate have always been considered as important investment instruments. Gold is commonly accepted as a safe haven in the literature, and the REITs are considered as long-term investment instruments by many scholars. While gold prices increase in the windy periods, the returns of real estate investments have more cyclical movements based on mostly the macroeconomic conditions and its integration with stock markets, yet the real estate is a common long-term investment tool, especially because of the regular income it generates for the retirement years. By covering three crisis periods including the COVID-19 pandemic-based economic crisis effects, making research about two important investment tools would contribute to the literature, especially in which the studies in this area were very limited.

The study aimed to investigate the relationship between the intention to avoid food waste (IAFW) and the use of food-sharing technologies, such as internet platforms and mobile applications. The study utilized a model based on the theory of planned behavior (TPB) as an extension of the unified theory of acceptance and use of technology (UTAUT2).

An online platform tool (Prolific), and online self-report questionnaires were used to gather empirical data on 309 individuals. These data were then analyzed using two-step structural equation modeling.

The model explained 76% of the variance in user adoption of food-sharing mobile applications and internet platforms, supporting seven out of the nine tested hypotheses. Effort expectancy, social influence and IAFW were found to be the significant determinants of the behavioural intention to use food-sharing mobile applications and internet platforms (BITA). IAFW partially mediated the relationship between perceived behavior control and BITA. Age played a moderator role between the adoption of food-sharing mobile applications and internet platforms. However, IAFW did not play a mediating role between environmental concerns and BITA. The facilitating condition construct had an insignificant impact on BITA.

The current study was affected by some limitations. First, the data may not be considered as statistically representative because they were gathered online. However, the varied sociodemographic backgrounds of the respondents would boost the reliability of the findings. However, it would be prudent to use caution when extrapolating these findings to other contexts and cultures. Second, environmental concerns and perceived behavior control related to the avoidance of food waste behavior, as well as other factors that affect technology acceptance, may alter with time. Data from cross-sections may cause difficulties in following such changes. Thus, we recommend that longitudinal research studies aimed at building on our findings should be conducted. A qualitative study may help gain deeper insights into the relationship between IAFW related behavior and the adoption of various technologies to share leftover food, thereby revealing further details regarding different perspectives held by various respondents.

The positive relationship between environmental concerns and IAFW underlines the significance of investing in this area to raise social awareness and public concern for environmental safety. Additional initiatives aimed at increasing public concern regarding environmental issues may increase the overall IAFW. Instead of concentrating on a single source pertaining to the avoidance of food waste, the government and policy regulations should focus on regulating and eliminating waste from all sources that generate waste. The adoption of technology to share leftover meals may be influenced by social factors. Increased advertising for food-sharing mobile apps and online platforms may persuade more users to join. Additionally, building additional platforms and mobile apps in these fields with friendlier interactions may improve the cyber environment, making it easier for people to use them. By providing information, tools and assistance to promote the reduction of food wastage, policymakers may create interventions that enhance public perception and behavior toward the reduction of food waste. In conclusion, the findings of our study indicated that the social impact and ease of use are important factors in determining the adoption of food-sharing technology. Cooperation with social influencers, policymakers and developers may lead to the development of user-friendly technology that may improve accessibility to food-sharing technology.

In order to encourage the adoption of food-sharing technology among various age groups, policymakers may create initiatives that take the specific requirements and traits of each group into consideration. Policymakers and governments may also create legislation and regulations that are tailored to guarantee food safety and health security for users of food-sharing technology, such as instructions for handling and storing food as well as safeguards against food fraud and contamination.

This study addressed practical issues related to managing and reducing household food wastage through social sharing via mobile applications and internet platforms. The proposed model, which integrated TPB with UTAUT2 in the context of food wastage and technology acceptance, contributes to the current body of knowledge.

The purpose of this study is to do a numerical analysis of the jet to a body filled with phase change material (PCM). The melting of the PCM filled body was investigated by the hot jet flow. Four different values of the Reynolds number were taken, ranging from 5 × 103 = Re = 12.5 103. Water, Al₂O₃ 1%, Al₂O₃ 2% and hybrid nanofluid (HNF; Al₂O₃–Ag mixture) were used as fluid types and the effects of fluid type on melting were investigated. At 60 °C, the jet stream was impinged on the PCM filled body at different Reynolds numbers.

Two-dimensional analysis of melting of PCM inserted A block via impinging turbulent slot jet is numerically studied. Governing equations for turbulent flow are solved by using the finite element method via analysis and system fluent R2020.

The obtained results showed that the best melting occurred when the Reynolds number increased and the HNF was used. However, the impacts of using alumina-water nanofluid were slight. At Re = 12,500, phase completion time was reduced by about 13.77% when HNF was used while this was only 3.93% with water + alumina nanofluid as compared to using only water at Re = 5,000. In future studies, HNF concentrations will change the type of nanoenhanced PCMs. In addition, the geometry and jet parameters of the PCM-filled cube can be changed.

Effects of impinging jet onto PCM filled block and control of melting via impinging hot jet of PCM. Thus, novelty of the work is to control of melting in a block by impinging hot jet and nanoparticles.