Eng

In this paper, an analysis of the geometry, numerical modeling, and experimental verification of thermofoil heaters for low-temperature applications is presented. The research suggests a calculation procedure of the thermofoil traces’ geometry, comprising the necessary electrical and thermal parameters in order for the characteristics of the heater to be fully defined according to the stipulated conditions required. The derived heaters’ geometry analysis procedure is depicted with two case studies, giving the sequence of the necessary calculations and their applications as part of a design task. Its continuation, the design approach, is developed with numerical modeling, based on Finite Element Methods (FEM) used for multiphysics simulations, including the thermal and electrical heaters parameters. The realized 3D models are used to depict the uniformity of the thermal field in the system heatsink-thermofoil heater. The results from analysis, modeling, and simulations are tested experimentally. The suggested geometry analysis and modeling approach are experimentally verified. The final results demonstrate satisfactory precision with a simulation–experiment mismatch in a range of 5–7%. As a vital product of experimental research, the maximum power density for the studied thermofoil heaters is derived for a range of temperatures and material characteristics. Full article

Construction of civil engineering structures on or next to a slope requires special attention to meet the bearing capacity requirements of soils. In this paper, to address such a challenge, we present laboratory-scale model tests to investigate the effect of footing shape on the sloped surface. The model comprised of a well stiffened mild steel box with three sides fixed and one side open. We considered both with and without reinforcement to assess the effectiveness of reinforcement on the sloped surface. Also, we used three types of footing (i.e., square, rectangular, and circular) to measure the footing shape effects. We considered three different slope angles to evaluate the impact of the sloped face corresponding to the applied load and the reinforcement application. We obtained that the maximum load carrying capacity in the square footing was higher than the rectangular and the circular footing for both the reinforced and the unreinforced soil. With the increase of geo-reinforcement in all three footing shapes and three sloped angles, the load carrying capacity increased. We also noticed a limiting condition in geo-reinforcement placement effectiveness. And we found that with the increase of slope, the load bearing capacity decreased. For a steep slope, the geo-reinforcement placement and the footing shape selection is crucial in achieving the external load sustainability, which we addressed herein. Full article

The renovation or the functional transformation of existing stock to meet the new comfort standards and energy demand reduction often requires comparing alternative technological options and designing solutions especially when it involves historical buildings where the main goal is usually to preserve the original image and value of the building. The paper reports a study regarding the potential covering of the inner courtyard of Palazzo Poggi in Bologna with a roof to create an intermediate new space between outdoors and indoors to be used all year long. The study is particularly focused on the definition of a simplified algorithm to predict and evaluate the annual temperature trend of the court, once it has been covered, assuming some geometrical and thermal characteristics of the roof. The paper describes the calculation algorithm and its application on the Palazzo Poggi case study where a covering in EFTE (ethylen-tetrafluorethylen) membrane is supposed to be created. Full article

Non-steroidal anti-inflammatory drugs (NSAIDs) are the group of drugs most commonly used in medicine. They are available over the counter to treat fevers and pains of various origins. The clinical and pharmaceutical analysis of these drugs requires effective analytical procedures for drug quality control, pharmacodynamic and pharmacokinetic studies. This article presents the spectrophotometric method that was used to analyze selected drugs from the NSAID group. The conditions for the determination of selected coxibs and oxicams in the UV range with the use of microplates have been developed. The presented procedure has been validated in accordance with the requirements, guaranteeing reliable results. The obtained results give the basis for the conclusion that the method can be successfully used in the quality control of pharmaceutical preparations with a small amount of available sample. Full article

Scour is caused by the erosive action of flowing water, which causes materials from the bed and the banks of a river to be moved or unsettled. Hydraulic structures can be drastically impacted as a result of scour, which is why it is one of the most common causes of bridge failure around the world. With a predicted increase in climate conditions, the subsequent failure of hydraulic structures due to scour is likely to proliferate as the flooding of waterways is projected to rise. This study aims to determine the viability of introducing alternative materials to a scour countermeasure used in construction—gabion models—in a bid to improve the sustainability of a project whilst providing suitable scour mitigation measures. Existing literature was examined to comprehend the different scour countermeasures used, as well as the use of alternative materials that can be used as a scour countermeasure. A laboratory experiment was then carried out using a bridge pier embedded in a flume channel protected by gabion mattresses filled with alternative materials—stone, clothing and plastic—to analyse their effectiveness. The results demonstrate that stone filled gabions are most effective at reducing bridge pier scour. However, recycled clothing as a gabion fill could prove to be a viable alternative in construction projects, potentially leading to reduced construction costs and greater sustainability. However, more research on a greater scale is required to test this thesis. Full article

The joining of two chemically dissimilar metals is a challenge due to the formation of hard and brittle intermetallic compounds (IMCs) in the diffusion layer. The joining of steel/Fe with aluminum (Al) and zirconium (Zr) alloy is particularly important for the automobile and nuclear industries, respectively. The Al–steel and Zr–steel joints produced by conventional fusion welding exhibit IMCs. The IMCs can enhance brittleness and cause catastrophic failure. This concept paper presents a novel idea of suppressing IMCs in welded joints using a high-entropy interlayer (HEI). It also discusses the potential candidates for HEIs and inspires research to exploit this new and promising research area. Full article

The surface roughening and martensitic phase transformation (MPT) of SUS 304 and SUS 316 were studied through two experiments: a uniaxial tensile stress test, repeated for five cycles, and an Scanning Electron Microscope–Electron Backscaterr Diffraction (SEM-EBSD) investigation. The MPT and martensitic volume fraction (Mf) were evaluated following the tensile test. The correlation between MPT, Mf, and surface roughening behavior was investigated. The experiment showed that an increase in the strain level from 0.4% to 1% increased the MPT and Mf, which transformed from a metastable austenitic phase in SUS 304. The increased strain level increased the surface roughening for various grain sizes (Dg), from fine grain (Dg < 3 μm) to coarse grain (Dg ≥ 3 μm). SUS 304 and SUS 316 are used so that the surface roughening mechanism between SUS 304 and SUS 316, with different phase conditions and at a similar Dg, can be determined. The results showed that the surface roughening increased for both fine and coarse grain at strain levels of 0.4% and 1%; however, a larger increase of surface roughening was obtained for coarse grain. In coarse grain, surface roughening increased significantly not only with a low MPT, but also with a low grain deformation. In coarse grain, the surface roughening increased proportionally to the strain level (εp) because of the low MPT and weak grain. In fine grain, the surface roughening did not increase proportionally to the εp because of the high MPT, which increased the grain strength in SUS 304. In the fine grain of SUS 304, the increase of surface roughening was nearly the same both at strain levels of 0.4% and 1%, because the MPT and Mf were nearly the same. The surface roughening with the same εp and almost the same Dg in SUS 304 and SUS 316 fine grain was nearly the same, because the grain deformation almost produced the same relative inclination between neighboring grains in the initial state direction to the surface. The inter-grain movement changed the grain orientation. Based on kernel average misorientation (KAM) mapping, the local grain misorientation in SUS 304 was higher than that in SUS 316. This indicated that the fine-grain SUS 304 is harder than the fine-grain SUS 316. There is no MPT in SUS 316 because of the higher austenitic phase, which is affected by the austenitic former, such as Ni. Full article

Flooding is one of the climatic change consequences that has become a dangerous threat to many coastal cities. Pervious concrete is considered a solution to decrease rainwater runoff and mitigate flood effects, as it allows water to percolate through the ground and prevent possible damage. Using waste products as aggregates in pervious concrete not only exploits waste materials and makes it valuable but also reduces the amount of this waste ending in the landfill or harming the environment, and it decreases the demand for natural resources. Infiltration rate test and compressive strength tests were conducted to investigate the effect of using waste plastic and/or recycled rubber as concrete coarse aggregates with different ratios (5%, 10%, 15%, 20%, and 25%) on the pervious concrete. The results showed that increasing the waste materials in concrete decreased the compressive strength for all ratios while increased the infiltration rate values. Full article

In the context of electricity production in remote areas, the use of diesel generators, either alone or in hybridization with renewable energy sources, faces many technical problems. Indeed, the electrical instability that often characterizes the isolated networks, due to the fluctuating character of renewable resources and the high variability in the load profile, leads to the operation of the diesel generator in transient dynamic conditions, at low loads or outside prescribed environmental conditions. Furthermore, the extended operation of the diesel generator at low charge results in the condensation of combustion residues on the engine cylinder walls, which, after a certain time, increases friction, reduces the efficiency and increases fuel consumption. One way to solve this problem and to eliminate these deposits is to operate the engine at a higher speed until the operating temperature is reached. This paper explores the impact of the wind turbine penetration rate for hybrid wind–diesel systems and the effects of cold temperatures, high altitude, and other environmental operation conditions on diesel generators’ performances. We outlines the impacts of low load and environmental conditions such as ambient temperature, humidity, moisture, abrasive dust, cold and corrosive environments on the operation of modern diesel generators. The problem has been approached by examining the existing literature, researching damage cases, analyzing existing data, and assessing industrial experiences. Full article

The device under investigation in this paper consists of a float used to capture tidal energy, which is tethered by multiple flexible cables to a large barge-like reactor. The proposed float is made of a continuously wound glass-reinforced composite shell with stainless steel bolting plates integrated into the float walls to allow the connection of 5 stainless steel cables. Numerical computations are required to assess whether a delamination of the composite layers in the float is likely. The manufacturing of the device has various potential uncertainties that should be investigated, such as the number of the plies, the bond strength between the composite layers, and the fibre orientations of the composite material relative to the applied load. This paper provides a multi-level strategy to optimise the composite float system, which is manufactured from glass-reinforced plastic (GRP). In contrast to previous publications on the topic, the current work uses an efficient link between ANSYS Workbench and MATLAB through an in-house code that has been developed over 3 years. This allowed the whole process to be fully automated and to reduce the time and cost of the simulations. Previously, ANSYS APDL was linked to MATLAB, but limitations in terms of the geometry and boundary conditions made it impractical when compared to ANSYS Workbench for the simulation of complex features. This makes the current approach unique and rare when compared to the published work in the field. This approach allows the use of a huge number of trials and is able to reduce the number of parameters to be studied by selecting the most sensitive ones. Additionally, the developed tools may be used for the efficient, robust optimisation of the proposed structure. The current study has focused on exploring the effects of the fibre orientations and the optimum number of plies on the overall performance of the structure. Full article

This study took the ergonomics design course as an example to propose a design teaching model of multidisciplinary participatory design (MPD), and investigated the effects of this teaching model on the engineering design behavior of college students. We used lag behavior sequential analysis to compare the design behaviors of three student groups: a participatory design (PD) experimental group, an MPD experimental group, and a control group. The results of the study show that (1) students in the PD experimental group had 13 significant sequential engineering design behaviors, students in the MPD experimental group had 10, and students in the control group had only seven. The engineering design behaviors of the experimental groups were more diversified than those of the control group. (2) The three groups of students had a small number of significant design behavior transfers in the engineering design process, indicating that the students’ sequential design behaviors between two different design activities were insufficient. We concluded by detailing the pros and cons of using the MPD teaching model based on the results of this study, and hopefully by providing a reference for teaching engineering design. Full article

Geographic information systems (GIS) and multicriteria decision methods are robust techniques for supporting the urban planning process, including urban drainage. New low-impact management approaches (LID) for rainwater have been investigated and have become increasingly used. Considering the central region of Pato Branco city, which suffers recurrent problems related to flooding, this work presents a method to identify potential areas for the application of LIDs, such as rainwater collection tanks, permeable pavements, green roofs, and rain gardens. The identification of these areas is based on the analysis in a GIS environment considering criteria related to both the land slope, the characteristics of land use and technical parameters. Thus, we observe that rainwater collection tanks are indicated for all habitations, permeable pavements are recommended for 6.30% of the study area, while green roofs can be implemented in 3.97% of the area. Finally, 3.03% can receive rain gardens. In total, 13.30% of the central region of Pato Branco can receive LIDs. The results obtained reveal that the use of the GIS tool associated with multicriteria analysis is efficient in choosing locations for the implementation of LIDs as alternatives for the management of urban drainage. Full article

In the numerical analysis of the Laplace equation, which is the governing equation of the seepage phenomena of homogeneous, isotropic earth dams, it has been confirmed that numerical analysis with high accuracy is possible by using the interpolation finite difference method (IFDM). In a previous paper, based on this numerical analysis method, the equivalent Kozeny (KZ) flow method was proposed as a new empirical method to calculate the seepage discharges and free surface locations of earth dams. Although this method is generally a highly accurate method compared with the empirical method of A. Casagrande, owing to calculating the seepage problems within a few percentages of discharge relative errors, several additional studies are necessary. By integrating the finding of this study to the previous literature, an empirical seepage calculation system with high accuracy, the equivalent KZ flow method, is created. Owing to the finally proposed empirical method, called “interpolation-equivalent KZ flow method”, the discharge and free surface location can be predicted with high accuracy in a wide range. Full article

Aggregates are generally thought of as inert filler within a concrete mix, and a typical concrete mix is comprised of as much as 70–80% of them. They play an essential role in the properties of both fresh and hardened concrete. Nowadays, scientists are aiming to use waste materials, thereby replacing natural aggregates for economic and environmental considerations. This study investigates the effect of the utilization of steel slag by-product aggregates (air- and water-cooled slag) as concrete aggregates on the behavior characteristics of concrete. Various concrete mixtures, with different levels of replacement of slag aggregate (50, 75, and 100%), were conducted in order to find the optimum percentages to improve the microstructure and different properties of concrete (fresh and hardened). The results showed that increasing the fine aggregate replacement percentage led to a decrease in compressive strength values, in contrast with coarse aggregate replaced with slag aggregate. The steel slag aggregates showed potential to be used as replacement for natural aggregate with comparable compressive strength and acceptable workability. Full article

This paper deals with the effects of initial stress on wave propagations in small-scale plates with shape memory alloy (SMA) nanoscale wires. The initial stress is exerted on the small-scale plate along both in-plane directions. A scale-dependent model of plates is developed for taking into consideration size influences on the wave propagation. In addition, in order to take into account the effects of SMA nanoscale wires, the one-dimensional Brinson’s model is applied. A set of coupled differential equations is obtained for the non-uniformly prestressed small-scale plate with SMA nanoscale wires. An exact solution is obtained for the phase and group velocities of the prestressed small-scale system. The influences of non-uniformly distributed initial stresses as well as scale and SMA effects on the phase and group velocities are explored and discussed. It is found that initial stresses as well as the orientation and volume fraction of SMA nanoscale wires can be used as a controlling factor for the wave propagation characteristics of small-scale plates. Full article

The energetic and environmental performance of a cogeneration biomass gasification plant, situated in Thessaly, Greece is evaluated via a methodology combining process simulation and Life Cycle Assessment (LCA). Initially, the gasification process of the most common agricultural residues found in the Thessaly region is simulated to establish the effect of technical parameters such as gasification temperature, equivalence ratio and raw biomass moisture content. It is shown that a maximum gasification efficiency of approximately 70% can be reached for all feedstock types. Lower efficiency values are associated with increased raw biomass moisture content. Next, the gasifier model is up-scaled, achieving the operation of a 1 MW_el and 2.25 MW_th cogeneration plant. The Life Cycle Assessment of the operation of the cogeneration unit is conducted using as input the performance data from the process simulation. Global Warming Potential and the Cumulative Demand of Non-Renewable Fossil Energy results suggest that the component which had the major share in both impact categories is the self-consumption of electricity of the plant. Finally, the key conclusion of the present study is the quantification of carbon dioxide mitigation and non-renewable energy savings by comparing the biomass cogeneration unit operation with conventional reference cases. Full article