a.k. salehi

When performing reactor core neutron calculations, the main cost lies in cell calculations to generate macroscopic cross-sections of fuel assemblies (FAs). The development and utilization of a cross-section library based on the reactor type is the primary procedure to reduce calculation costs. In some cases, when there is no library available for specific analyses, it becomes necessary to conduct cell calculations. Examples of such cases include investigating FAs vibration neutron noise or coolant asymmetric distribution around FAs due to bowing. In this study, an Artificial Neural Network (ANN) was used instead of high-volume cell calculations to significantly reduce the time required for calculations in the VVER-1000 reactor. For criticality calculations at Beginning of Cycle (BOC), the calculation time was reduced from 42 minutes using 32 computational cores to just 1.3 minutes. Additionally, the results achieved were of acceptable accuracy, with the difference in the critical boric acid value obtained using ANN compared to cell calculation as a reference being less than 1%, and the power difference being less than 5%.

The study aims to use the opinions of experts to analyze the factors involved in the financial empowerment of hotels in crises, with an emphasis on the prevalence of COVID-19 in five-star hotels.

The population consists of administrative and managers, and the sample size consisted of 384 members of the studied hotels. The questionnaire was sent to the sample members via social media, or they answered the online questionnaire. Smart PLS software was used to analyze the raw data and the research model was designed using structural equation modeling.

According to the main hypothesis, controlling coronary disease will improve the financial condition of hotels, and this hypothesis was confirmed with a coefficient of β: 0.781. As sub-hypotheses of factors of creating consistent use, consistent use change, reducing unnecessary costs, maintaining customer relationship and marketing in proportion to the coefficients of β:0.594, 0.506, 0.591, 0.623, 0.523 were confirmed as effective factors in financial empowerment. On the other hand, restricting businesses, reducing unnecessary traffic, and emphasizing social distance with coefficients of β: 0.498, 0.522, 0.618 were approved as effective factors in disease control.  

Because the specific time for the end of the Coronavirus epidemic is not known; therefore, closure is not a good solution to overcome the virus in the hotel industry. Adapting the business to the new conditions can be a good way to financially empower the hotel industry. On the other hand, observing the factors discussed in disease control in the present study can cause disease control; since disease control is ultimately directly related to the hotel's financial empowerment. Finally, it should be said that the most important achievement of the present study is to present a financial crisis management approach during its occurrence.

The performance of a uranium gas centrifuge which is used in the uranium enrichment industry depends strongly on the gas flow field. The computer simulation is vital to examine the gas flow field. Therefore, in the present study, the capabilities of OpenFoam software for simulating the gas flow inside the rotor for total reflux thermal drive-in axisymmetric mode has been investigated. The results corresponding to the OpenFoam ssimulation have been validated with those of analytical Olander’s model, numerical solution of the Harada’s study, and simulation using Fluent. The simulation results for gas flow inside the rotor of centrifuge showed that the density-based solver was properly chosen and the number of cells, 160×170, was compatible with mesh. The numerical results show that OpenFoam software was capable to examine the gas flow inside the rotor. Also, the simulation of the distribution of Knudsen number confirms the presence of the molecular region near the axis of rotation. OpenFoam is open-source software and there is the ability to solve the molecular region as well as the coding for coupling the continuous and molecular region, the feature which does not exist in the fluent software. The use of open foam is therefore recommended to simulate gas flow inside the rotor.