مجله مهندسی مکانیک
پیاپی 145 (مهر و آبان 1401)

Paying attention to the environmental hazards of traditional energies, especially the phenomenon of global warming caused by the release and concentration of greenhouse gases, is one of the main reasons for paying attention to new energies and it has prompted the governments to seriously put the benefit of new sources of energy on the agenda and plan for it. On the other hand, it is appropriate that existing potentials such as energy loss due to gas pressure reduction in urban gas reduction stations should be considered and investigated. Therefore, in this article, it has been tried to produce electricity by using a turbo expander in a municipal gas pressure reduction station. The gas input to this turbo expander is also preheated by geothermal energy to increase the work production capacity. The results indicate that the most ideal isentropic efficiency (equal to 90%) occurs at the turbo expander inlet temperature equal to 80 degrees Celsius and the amount of preheating equal to 186.5 kJ/kg. Also, increasing the amount of natural gas preheating increases the temperature of the expansion turbine and as a result, the production power increases.

An interactive and ergonomic wheelchair equipped with a health service system has been designed. Its primary goal is to meet the mobility of the different persons with disabilities. At the same time, its secondary goal is to provide novelty health services such as urination and defecation by observing the tips and health space. This research is applied in terms of purpose and qualitative-descriptive in terms of nature. As a practical matter, it has used two methods of verbal-visual (questionnaire, interview) and non-verbal (observation) by survey method to collect data and benefit from analysis by relevant expert (Delphi) groups. Its design method was the so-called Design up (Tarrahi Nameh in Persian) which was based on the interaction design and user-centered approach and has employed Analytical Hierarchy Process (AHP) to prioritize users. The result is the interactive and ergonomic wheelchair equipped with a health service system under the Sabita brand, which has an effective, efficient and safe means of transportation. It enjoys the sanitary system of defecation in a hygienic environment along with washing and purification, which is the main need of its users and finally seeks their satisfaction and pleasure. The Sabita wheelchair, also, facilitates the work of physically able-bodied assistants. Six elements of usability such as effectiveness, efficiency, safety/comfort, utility, learnability and memorability, on the one hand would be brought. The goals of interaction design as visibility, feedback, constraints, consistency, affordance and engagement user experience, on the other hand, would be illustrated.

Head and neck cancer is a disease that often affects the mouth, throat and nose. This type of cancer causes damage to other cells and complications such as hearing and taste damage through treatment methods such as surgery and chemotherapy. Studies have been done on the use of nanoparticles as drug carriers, understanding the structure of cancer cells and investigating their mechanical properties. In this study, in order to improve the treatment and early diagnosis of this type of cancer, the Young's modulus of head and neck cancer cells was estimated using the nanomanipulation process. The topographic images and experimental graphs used were extracted by exploring the head and neck cancer cells under AFM. The main innovation of this research has been in the use of JKR, MD and Tatara contact models. The main aim of the research is to draw indentation depth graphs according to applied force to estimate Young's modulus of Head and Neck tissue. By comparing the theoretical and experimental results of the 12 KPa Young modulus with the JKR model and the value of 11 KPa with the Tatara contact model, the values of the Young modulus of the head and neck cancer cell are estimated. 

In this paper, an intelligent integral Back-step controller is used to control the position of the quadrotor. Using a new strong particle swarm optimization algorithm, the optimal system response is Achieved by changing constant design values in the controller. Then, the optimal path for the quadrotor is designed using the algorithmic method of particle swarm and considering the predetermined obstacles in the three-dimensional environment, which ensures safety flight. Also, the shortest path between the origin and destination as the optimal path is determined. Finally, the path generated by the algorithm as the optimal path of planning. Thus, in addition to optimizing the control parameters in the controller, the quadrotor path is also optimized using the algorithm to minimize energy consumption from source to destination. Finally, by simulating the system in MATLAB environment, the system response to the desired input in a limited time was plotted and investigated.

In this article, Surface Active Agents (Surfactants) and its effect on the Multiphase Flow have been studied. First, the functioning of surfactants has been explained. For this purpose, the definitions of surface tension and how it changes in the presence of surfactants have been investigated. Also, the physics of surfactant distribution in multiphase flow and its absorption and repulsion at the interface have been reported. The physical changes of the two-phase interface due to the presence of surfactants have been investigated through the balance of forces and the change in surface tension and the definition of the Marangoni effect. Types of surfactants and their properties are stated. Finally, the important applications of surfactants in industry and daily life are mentioned in detail. This review shows that surfactants as one of the effective factors on multiphase flow need to be studied more and more. A better understanding of these materials can be very useful in manipulating and optimizing multiphase flow applications. 

In this paper,the heat transfer in the hot fuel rod of a pressurized nuclear reactor such as the Bushehr reactor has been investigated. Generally,in the thermal analysis of a nuclear fuel rod,special attention is paid to the temperature distribution in the constituent parts of the fuel rod,as well as the effect of the coolant flow around it on the amount of heat removal. Therefore,in this study,using the equations of heat transfer in the fuel rod,its adjacent coolant,the intensity of heat transfer,the effect of different parameters have been investigated. For this simulation,Ansys-Fluent (CFD) software,the nuclear code COBRA-EN have been used,in this modeling the EPRI model of the COBRA-EN code is used because of its conservativeness to calculate the critical heat flux,the maximum,average fuel temperature,enthalpy,temperature Coolant,mass flow rate of coolant has been used,its results have been compared with CFD results,reference results. Also,the thermo-hydraulic parameters of helium gas under pressure trapped between the fuel,clad have also been investigated.