مجله مهندسی مکانیک
پیاپی 137 (خرداد و تیر 1400)

Nowadays, due to the problems of fossil fuels such as Nonrenewability, environmental pollution, etc., renewable energies have become very important. Solar chimney is one of the renewable energy fields that can be used in power plants. The increasing use of solar energy in recent years has aroused great interest in the development of solar chimney technology. In this article, we study the components of a solar chimney power plant, which includes three main parts: collector, power conversion unit and chimney. Solar chimney power plants have low efficiency. Therefore, combining them with other technologies such as desalination and drying is recommended. Also, the optimization of effective parameters in Combined solar chimney system for power generation and seawater desalination has been investigated. Then, the results of experimental studies performed on solar chimneys from 1981 are reviewed. Also, The feasibility of installing a solar chimney power plant in different regions of Iran has been studied.

Process planning and management is a decision that uses limited resources to achieve a specific goal. Therefore, production management can be considered as a decision-making process in the field of production issues, planning, organizing, controlling, directing, or motivating human resources. Because in the industry, to ensure product responsiveness, they first act as a single production and workshop and then as mass production. In the present study, a CAD computer model and a fixture were made for the Peugeot 405 brake pump shell. According to the geometric shape of the sample, casting and machining methods are considered in the production of the product. The restraint was designed and made for the final-machining operation. With the help of planning tables and operations sheets, important product specifications, important process specifications, design plans were controlled and reviewed. The results show high compatibility between the production sample and the prototype of Iran Khodro (IKCO) Company. Due to the high compatibility, it can be claimed that the product produced is at a better level in terms of quality, manufacturing and ultimately cost.

Increasing the use of aluminum alloy sheets in the automotive industry, due to the high strength-to-weight ratio, requires improving the formability problems of this metal. Warm forming of aluminum alloys is a practical solution to improve and enhance this challenge. The purpose of this paper is to investigate the process of the non-isothermal warm deep drawing process by applying the pulsating blank holder force during forming that facilitates the material flow of the sheet while sliding into the matrix cavity. To this end, using the optimal results from a combination of experimental and numerical results at ambient temperature, deep drawing experiments were performed by applying a temperature gradient to AA5083 sheets with a thickness of 2 mm at 150 ◦C The results showed that in the non-isothermal warm deep process based on pulsating blank holder force, in addition to reducing the forming force, a significant increase in deep drawability was achieved compared with the constant blank holder force at ambient temperature.

Porous structures made of titanium have received much more attention due to their appropriate elastic modulus than other biometals, a significant reduction in stress shielding, and proper bonding with bone. Porous implants performance is a function of the type of alloy and the microstructural specimen properties, for instance, the size, the shape, the distribution of the pore, and part density. Therefore, to attain the optimized implant having the elastic modulus matched with the bone and the permeability for bone-cell growth, choosing the appropriate manufacturing method and controlling its parameters is essential. Considering that, in the present article, the mechanical properties of porous titanium implants fabricated by different methods have been gathered and evaluated. Among the different manufacturing methods, additive manufacturing (AM), spark plasma sintering (SPS), and metal injection molding (MIM), with high flexibility, provides porous structures having appropriate mechanical properties. However, the high cost of additive manufacturing methods compared to the other two routes seems challenging for commercializing AM for producing porous titanium implants.

The use of appropriate technologies for transportation as fast as possible and at the same time, a smooth and safe journey has always been one of the main demands and concerns of human beings throughout history. Hyperloop technology is one of the most important transportation systems (fifth generation) introduced in the world in recent years. Hyperloop is a very fast passenger or cargo transportation system that has been introduced as the newest (fifth generation) and fastest transportation system in the world. According to the latest reports, the system can reach speeds of up to 1,200 Km/hr (approximately equivalent to the speed of sound), which means that transportation and travel will be very fast. Therefore, the vibrational, acoustic, and stability issues of these systems, are very important. The overall operation mechanism of these systems is the movement of a very high-speed capsule shape vehicle (called a pod) with some passengers inside the tubes close to the vacuum conditions. In this article, while introducing and reviewing the hyperloop system and its components, the feasibility of use, costs, and comparison of the performance of this technology with other transportation systems in a quantitative and qualitative manner are discussed. Finally, the technical specifications of a real designed example of these systems are expressed.

Flange joints are one of the most widely used components in industries and failure of joints results hazards to the environment, and economic loss. The methodology and magnitude of external forces applying cause failure therefore flange leakage. In this study sealing performance of flange joint with four gaskets under mechanical loads (internal pressure, bending moment, axial force and bolt load) simultaneously is studied by numerical simulation in Abaqus. The results show that bolt load is more effective on sealing performance than bending moment and in addition to, 25 percent increasing of bolt loads causes 13 percent increasing for contact gasket stress which improves sealing performance. There is an inverse relationship between modulus of elasticity and sealing performance such that gaskets with lower modulus have better sealing.

Arteriovenous malformation is a disease of the vascular system of the human body that occurs mainly in the cerebral vessels and spine. In this disease, blood flow, contrary to normal, instead of passing through the capillary section, is transferred directly from the artery to the vein, and if it progresses, it can lead to rupture and cerebral hemorrhage. Common treatments include surgical resection, embolization, and radiation therapy. Modeling and simulating blood flow in the vascular system of the human body helps physicians to have a better understanding of vascular diseases and how they develop so that they can make the right and important decisions before surgery. The three most common types of modeling for vascular blood flow are mathematical, mechanical, and electrical modeling, each of which has undergone significant studies. In the present study, the types of modeling and related studies have been investigated.

The laser cladding process is considered as one of the attractive and complex areas of laser. In recent years, various fields of study have been introduced for laser cladding. The purpose of this study is to introduce these areas in an applicable way. Regarding to this, the reasons for the superiority of the laser cladding process over other cladding methods will be investigated by introducing related studies. Due to the complexity of laser cladding, this technology is introduced in simple interpretation way in a separate section. Then, the types of laser processes are compared based on previous studies. In the following, the effect of the main process parameters such as power, laser beam diameter, travel speed, feed rate and shielding gas on the resulting clad parameters such as hardness, dilution, porosity and melt pool temperature will be investigated based on related studies. In addition, the effect of process subsidiary parameters such as overlap, path direction, preheat and post heat on clad parameters such as strength, maximum feed and hardness will be introduced using recent studies. Thus, different aspects of laser cladding studies in recent years will be provided for researchers and industries of this technology in a practical way.