Search Results (11)

Background: Ocular toxoplasmosis remains the leading cause of posterior uveitis worldwide. Optical coherence tomography (OCT) provides valuable insights into the structural alterations associated with this condition. The present study aimed to characterize the vitreous, retinal, and choroidal morphological changes observed during both the active and scarred stages of ocular toxoplasmosis using OCT imaging. A secondary objective was to evaluate the added value of three-dimensional reconstruction in the assessment of retinal lesions. Methods: A retrospective study was conducted on 12 eyes belonging to 12 patients diagnosed with toxoplasmosis retinochoroiditis (TRC). Optical coherence tomography (OCT) scans centered on the active lesions were qualitatively analyzed at baseline and follow-up. Additionally, a ResUNet model was trained to generate a full volumetric reconstruction of the retinochoroidal lesions in selected cases. Results: Twelve eyes were analyzed at a mean of 16.2 days from symptom onset. The mean follow-up duration was 144 days (range: 12–490 days). OCT imaging revealed characteristic alterations in the retina, choroid, and vitreous body, which were documented both at baseline and at follow-up. Representative cases were selected for three-dimensional reconstruction to illustrate the extent of retinal architectural involvement. Conclusions: OCT analysis refines our understanding of the structural damage associated with ocular toxoplasmosis, while three-dimensional reconstruction enhances our ability to visualize and interpret these alterations on a larger scale. Full article

Monitoring the behavior of structures over time is a defining activity for any type of construction that provides data necessary to assess whether these structures meet requirements for stability and durability. In today’s rapidly urbanizing world, it is essential to monitor construction projects. Whether monitoring the impact on buildings surrounded by new constructions, underground infrastructure, or high-rise structure projects, the solutions and results provided by the construction monitoring process, carried out during the execution phase and/or operational stage, enable communities to progress and thrive without jeopardizing people and assets. This study aimed to highlight the level of interest in structural monitoring activities. A bibliometric analysis based on scientific articles published in the most popular databases brings to the forefront correlations and links between various fields of activity and the domain of construction monitoring through the application of various technologies. These published studies and the centralization of the number of searches for specialized terms related to structural health monitoring activities present a combination of classical theories with modern technologies that have evolved rapidly due to the continuous development of civil and geodetic engineering technology, as well as the introduction of artificial intelligence in interpreting recorded observations. This research results show that this topic is relevant and increasingly studied; for example, the number of scientific articles published on this subject doubled in the last three years compared to previous years. According to the literature, research trends are focused on new technologies, including the application of various sensor types, UAV technology, and LiDAR. The number of publications showed an increased interest in the study, monitoring, and evaluation of bridges, followed by research on civil constructions. Among civil constructions, aging or special buildings were most frequently encountered, while new structures accounted for a smaller percentage according to scientific articles published in the specialized literature. Full article

A real-time, effective, and dynamic taxi cruising recommendation strategy is essential to solving the problem of taxi cruising passenger difficulty and urban road traffic congestion. This study focuses on two aspects of the real-time accessible range and pick-up ratio (PR) and proposes a real-time dynamic identification method for taxi optimal cruise-seeking area. Firstly, based on the cumulative opportunity method, a univariate temporal convolutional network (UTCN) accessible range dynamic prediction model is proposed to predict the real-time accessible range of taxis. Secondly, based on the gradient boosting decision tree (GBDT) model, the influencing factors with a high correlation with the PR are selected from the four dimensions of traffic characteristics, environmental meteorology, and time and space variables. Then, a multivariate univariate temporal convolutional network (MTCN) global grid PR prediction model is constructed, and the optimal taxi cruising area is identified based on the maximum PR. The results show that the taxi accessible range and PR of the same grid in different periods change with time, and based on the model comparison, the accessible range and PR prediction results of UTCN and MTCN algorithms in different periods are the best to identify the optimal cruising area of taxis in different periods. The main contribution of this study is that the proposed optimal cruising area prediction model has timeliness, accessibility, and dynamics. It can not only improve the probability of taxis receiving passengers and avoid taxis cruising aimlessly, but also solve the shortage of taxis in hotspots, thus shortening the waiting time of passengers. This provides a scientific basis for improving taxi cruising efficiency and the government’s formulation of taxi operation management policies, which can effectively promote the sustainable development of urban traffic. Full article

The use of waste from industrial activities is of particular importance for environmental protection. Fly ash has a high potential in the production of construction materials. In the present study, the use of fly ash in the production of geopolymer paste and the effect of Fe₂O₃, MgO and molarity of NaOH solution on the mechanical strength of geopolymer paste are presented. Samples resulting from the heat treatment of the geopolymer paste were subjected to mechanical tests and SEM, EDS and XRD analyses. Samples were obtained using 6 molar and 8 molar NaOH solution with and without the addition of Fe₂O₃ and MgO. Samples obtained using a 6 molar NaOH solution where Fe₂O₃ and MgO were added had higher mechanical strengths compared to the other samples. Full article

Nowadays, the disinfection of classrooms, shopping malls, and offices has become an important part of our lives. One of the most effective disinfection methods is ultraviolet (UV) radiation. To ensure the disinfection device has the required wavelength spectrum, we need to measure it with dedicated equipment. Thus, in this work, we present the development of a UV spectrum detector capable of identifying UV wavelength spectrums, with a wide range of probes and the ability to transmit data to a PC for later evaluation of the results. The device was developed with four UV sensors: one for UV-A, one for UV-B, one for UV-C, and one with a wide range of detection of UVA, with a built-in transimpedance amplifier. An Arduino Nano development board processes all the acquired data. We developed a custom light source containing seven UV LEDs with different central wavelengths to calibrate the device. For easy visualization of the results, custom PC software was developed in the Processing programming medium. For the two pieces of electronics—the UV detector and calibration device—3D-printed housings were created to be ergonomic for the end-user. From the price point of view, this device is affordable compared to what we can find on the market. Full article

Nowadays, due to recent global climate changes, replacing non-environmental friendly technology with more sustainable energy is desired. Thus, researchers are designing new, environmentally friendly products, for which some use the black box modeling method. Therefore, the presented work represents a Hampson-Linde cryogenic cooler model based on Joule-Thomson Effect and Ohm’s Law for thermal circuits, optimized using a parallel “Particle Swarm Optimization” (PSO) algorithm. An innovative feature of this model is that it uses two translations—from electrical to the thermal domain and a simplifying time domain—and is implemented to provide results using less demanding computational resources and simulation time. Furthermore, a possibility for superconductive states is presented for commonly used category II superconductors. Last, but not least, based on the predicted output temperature, models of more complex processes could be developed, such as a model for the Hyperloop concept. Full article

The applied electronics domain has great importance due to many applications, such as energy conversion, directly influencing specific processes involving renewable energy. The development of newer manufacturing processes for many integrated components allows for better overall efficiency in certain switching DC/DC converters used for implementing such low-voltage electric field or X-ray generators. Hence, the work presented in this paper involves the development of a helical resonator using a complex DC/DC low-voltage power supply and other required high-voltage conversion circuits. It also follows that there is a possibility of improving this design using only renewable energy supplies. Following two different approach methods, using a circuit model compared to transmission line mathematics, the standing wave propagation mathematics yields multiple scenarios for building a model that predicts the secondary side natural frequency. Moreover, standing wave occurrence conditions in various-dimensioned conductors were further investigated. Full article

This paper presents a comparative study between two maximum power point tracking (MPPT) algorithms, the incremental conductance algorithm (InC) and the fuzzy logic controller (FLC). The two algorithms were applied to a low photovoltaic power conversion system, and they both use different PI controllers and grid synchronization techniques. Moreover, both InC and FLC methods have Clarke and Park Transformation. To some extent, the incremental conductance and fuzzy logic controller approaches are similar, but their control loops are different. Therefore, the InC has classic Proportional Integrative (PI) controllers with simple phase-locked loops (PLL). At the same time, the FLC works with fuzzy logic PI controllers linked with the Second Order Generalized Integrator (SOGI). The proposed techniques examine the solar energy conversion performance of the photovoltaic (PV) system under possible irradiance changes and constant temperature conditions. Finally, a performance comparison has been made between InC and FLC, which demonstrates the effectiveness of the fuzzy controller over the incremental conductance algorithm. FLC turns to convert photovoltaic power easily, decreasing fluctuations, and it offers a quick response to the variation of solar irradiance (shading effect). The simulation results show a superior performance of the controller with fuzzy logic, which helps the inverter convert over 99% of the power generated by the photovoltaic panels. In comparison, the incremental conductance algorithm converts around 80%. Full article

The current context provides, worldwide, the need to identify solutions for the thermal efficiency of constructions, through sustainable and innovative methods and products. A viable solution is to produce thermal insulating products by carding-folding technology, using natural fibres and recycled polyethylene terephthalate (rPET) and polyester (rPES) waste, converted to fibres. This paper presents experimental results obtained after testing several thermal insulation composite products produced using a mix of sheep wool, cellulose, rPET and rPES fibres. The results of the research demonstrate the thermal insulation properties but, at the same time, identify the benefits of using such materials on the quality of the air in the interior space (the ability to adjust humidity and reduce the concentration of harmful substances). At the same time, the advantages of using sheep wool composite mattresses concerning their resistance to insect attack is demonstrated when compared with ordinary thermal insulation materials. Finally, sensitivity elements of these composites are observed in terms of sensitivity to mould, and to contact with water or soil, drawing future research directions in the development of this type of materials. Full article

Developing non-destructive methods (NDT) that can deliver faster and more accurate results is an objective pursued by many researchers. The purpose of this paper is to present a new approach in predicting the concrete compressive strength through means of ultrasonic testing for non-destructive determination of the dynamic and static modulus of elasticity. For this study, the dynamic Poisson’s coefficient was assigned values provided by technical literature. Using ultra-sonic pulse velocity (UPV) the apparent density and the dynamic modulus of elasticity were determined. The viability of the theoretical approach proposed by Salman, used for the air-dry density determination (predicted density), was experimentally confirmed (measured density). The calculated accuracy of the Salman method ranged between 98 and 99% for all the four groups of specimens used in the study. Furthermore, the static modulus of elasticity was deducted through a linear relationship between the two moduli of elasticity. Finally, the concrete compressive strength was mathematically determined by using the previously mentioned parameters. The accuracy of the proposed method for concrete compressive strength assessment ranged between 92 and 94%. The precision was established with respect to the destructive testing of concrete cores. For this research, the experimental part was performed on concrete cores extracted from different elements of different structures and divided into four distinct groups. The high rate of accuracy in predicting the concrete compressive strength, provided by this study, exceeds 90% with respect to the reference, and makes this method suitable for further investigations related to both the optimization of the procedure and = the domain of applicability (in terms of structural aspects and concrete mix design, environmental conditions, etc.). Full article

The development of mold films on the cement surfaces of buildings is a health and safety problem for the population, aesthetic but also in terms of their durability. The use of specific performance of cementitious composites containing TiO₂ nanoparticles, photoactivated by UV radiation, can be a viable solution to mitigate to eliminate these problems. The experimental studies presented aim to analyze the capacity to inhibit the development of mold type Aspergillus and Penicillium on the surface of composite materials with nano-TiO₂ content and the identification of the optimal range of nanomaterial addition. The identification and analysis of the inhibition halo (zone with a biological load of maximum 1–10 colonies of microorganisms) confirmed the biocidal capacity of the cementitious composites, but also indicated the possibility that an excess of TiO₂ nanoparticles in the mixture could induce a development of cell resistance, which would be unfavorable both in terms of behavior and in terms of cost. Full article