The paper analyzes the evolutionary path of additive manufacturing (AM), exploring its transition from a tool used exclusively for rapid prototyping to a mature production technology, a central pillar of the Industry 4.0 paradigm. The study emphasizes the shift in vision that additive manufacturing imposes on industrial design through the concept of Design for Additive Manufacturing (DfAM), which allows the creation of complex geometries that are impossible to achieve through traditional subtractive methods. In the context of the Fourth Industrial Revolution, the study highlights the integration of 3D printing with technologies such as Digital Twin, Artificial Intelligence, and Cloud Manufacturing, demonstrating how they converge to create smart and sustainable factories. Finally, current challenges related to standardization, material costs, and intellectual property are discussed, providing a perspective on the future in which additive manufacturing will redefine the circular economy and globalized production.
Increasing the amount of electricity produced by photovoltaic parks can be achieved by using mechanical solar tracking systems. One of the challenges is represented by the land area available for installing a photovoltaic park. To use the full potential of a land of a certain shape and surface, the paper proposes an optimization algorithm for the installation of fixed or mobile photovoltaic systems with the objective of maximizing the amount of electricity produced. Both fixed systems and mechanical solar tracking systems for photovoltaic module arrays developed in the Renewable Energy Systems and Recycling Research Centre of Transilvania University of Brasov and in other international research centres are presented. Aspects related to their installation, the solar tracking mechanisms used, their technical capabilities and the produced electricity are comparatively analysed.
This paper presents a comprehensive study of a truss beam, focusing on the design, analytical calculation, and computational validation of two configurations: one with welded joints and another with bolted joints. Analytical methods such as the method of joints were used to calculate internal forces in the beam members, followed by validation through the structural analysis software MDSolids. Additionally, a detailed Finite Element Analysis (FEA) was conducted using Ansys, examining key parameters like displacements and Von Mises stress. The results from both the analytical and FEA methods were compared to evaluate the performance of the welded and bolted truss beams.
An efficient technique for autothermal operation of catalytic fixed-bed reactors is the forced unsteady state operation by periodical flow reversal. This paper presents a mini review of the main investigations dedicated to the design and operation of this process, published over the past several decades. A case study is also presented, describing the particularities of process mathematical modelling and emphasizing the typical space and time evolutions of the main process variables. The case-study illustrates the use of packed beds of porous pellets with egg-shell type distribution of catalyst, which combines the high thermal capacity advantage of pellet packed beds with the minimal internal diffusion limitations on process kinetics typical for monolithic catalyst beds. A sensitivity analysis highlights the potential modelling errors that could be induced by the uncertainty in the evaluation of model parameters, using published correlations.
The study uses a transient multiphase flow simulator in order to evaluate the influence of operational parameters on the response of gas kicks with oil- and water-based drilling fluids (OBM and WBM) in high-pressure high-temperature (HPHT) wells. The approach is to use a dynamic multiphase flow simulation of gas kicks in drilling fluids. It uses fictitious well data with key variables, such as mud type, flow rate, liquid holdup, free gas volume fraction, flow pattern, fluid velocity, and mixture density. The analyses are performed at high (150 gpm) and low (75 gpm) flow rates in order to document the changes in fluid behavior. Moreover, close attention is given to the effect of increasing bottomhole temperatures (BHT) on kick circulation times. Even at higher circulation rates, the WBM presents slug flow with significant gas slippage, delaying dispersed bubble flow. Slug flow causes more gas bubbles to coalesce as the gas gets closer to the surface. On the other hand, the OBM exhibits a lower tendency for slug formation by maintaining a dispersed bubble flow pattern with little slippage between the gas and oil. Both types of mud restrict the flow of gas. In OBM, the gas gets trapped inside the oil under bottomhole conditions. Similar issues arise close to the surface in WBM. A higher BHT has an impact on this phenomenon. The study highlights multiphase transient simulators’ potential for well control and planning. It aims to help well planners and wellsite engineers understand gas kick incidents in HPHT wells.
