Search Results (28)

Numerous studies have demonstrated that appropriate use of daylight in educational spaces significantly enhances students’ health and academic performance. However, classrooms in Tehran still suffer from considerable daylighting challenges. In many cases, desks near windows are exposed to excessive brightness, while areas farther from the windows lack adequate illumination. This often leads to the use of curtains and artificial lighting, resulting in higher energy consumption and potential negative impacts on student learning. Light shelf systems have been proposed as effective daylighting solutions to improve light penetration and distribution. According to previous research, three key parameters—geometry, depth, and surface reflectance—play a critical role in the performance of light shelves. However, prior studies have typically focused on improving one or two of these parameters in isolation. There is a lack of research evaluating all three parameters simultaneously to determine season-specific configurations for optimal performance. Addressing this gap, the present study investigates the combined effects of light shelf geometry, depth, and reflectance across different seasons and proposes a system that dynamically adapts these parameters throughout the year. In winter, the system also integrates photovoltaic panels to reduce glare and generate electricity for its operation. Simulation results indicate that the proposed system leads to a 21% improvement in Useful Daylight Illuminance (UDI), a 65% increase in thermal comfort, and a 10% annual reduction in energy consumption. These findings highlight the potential of the proposed system as a practical and energy-efficient daylighting strategy for educational buildings in sunny regions such as Tehran. Full article

Semisteel is the byproduct of the titania slag smelting process of ilmenite concentrate with an electric furnace. To enhance the added value of semisteel, a centrifugal granulation–water curtain process was adopted to manufacture iron powders. The oxidation characteristics of granulated powders were analyzed by thermogravimetry (TG), X-ray diffraction (XRD), and scanning electron microscopy (SEM). To obtain iron powders with high purity, the isothermal oxidation kinetics of pure iron powders under vapor atmosphere were studied. TG measurements of pure iron powders were conducted at 1073 K, 1173 K, and 1273 K using a humidity generating instrument and a thermal analyzer. The results indicate that the oxidation rate increases with the increasing temperature and decreasing powder size. The entire isothermal oxidation process of iron powders with different sizes (0.3 mm < d₁ < 0.35 mm, 0.4 mm < d₂ < 0.45 mm, and 0.5 mm < d₃ < 0.55 mm) comprises two stages. The first oxidation stage is controlled by chemical reaction; the second oxidation stage is controlled by both internal diffusion and chemical reaction. The activation energies and oxidation reaction rate equations of iron powders at different stages are calculated. Full article

Annual energy consumption has surged due to suboptimal energy efficiency, resulting in an electricity supply shortage in Sulaimani, an Iraqi city in a temperate climate zone. This mixed-methods study aims to optimise energy efficiency in Sulaimani’s office buildings using IDA Indoor Climate and Energy (IDA ICE) dynamic simulation software v4.8. First, we collected data and developed 204 scenarios based on three prevalent plan typologies, linear (T₁), concentric (T₂), and courtyard (T₃), utilising common materials such as Alucobond (M₁), cement plaster (M₂), Styropor (M₃), and a curtain wall (M₄). Afterwards, we performed relevant analyses employing External Venetian Blinds (EVBs) to reduce cooling load and/or Expanded Polystyrene (EPS) to reduce heating load. Notably, the results proved that EPS was more effective than EVBs in reducing both heating and cooling loads in the temperate climate zone, achieving reductions of up to 38% for T₁. Meanwhile, EPS contributed to a heating load reduction of up to 52% for T₃, and this adversely impacted overall energy consumption. Both EVBs and EPS could reduce total energy consumption by up to 30% in T₂. In conclusion, the total energy consumption increased in temperate climate zones when EVBs were utilised, but this effect varied based on the various typologies of office buildings. Full article

The development of the field of textronics covers many directions, but the neediest are safety, medicine, and environmental protection. The solutions developed can combine the needs of many people from different social groups and ages. This leads to sustainable socio-economic, scientific and integrated approaches to sustainable development. The authors, seeing the growing need to monitor air pollution in order to increase safety, decided to develop textronic chemical sensors based on carbon-based inks and metal thread embroidery, sensitive to harmful gases and vapors based on textiles. This was to limit the production of subsequent sensors made in plastic housings containing difficult-to-recycle materials and replace them with sensors incorporated into everyday materials such as clothing, which will inform us about emerging threats not only in the place where a large plastic sensor is placed, but in every place at home, at work and outside where we will be. The authors assume that the sensors can be incorporated into clothing, e.g. work clothes, and can also be fastened from one piece of clothing to another. This increases their economic aspect and usability on a larger scale. Three materials of different composition were tested: cotton, polyester and viscose. These materials were selected based on their properties, namely the easier determination of their ability to achieve full circularity of the final product.Functional and mechanical tests of resistance to factors occurring during everyday use were carried out for the use of systems in clothing materials and to produce roller blinds and curtains. To examine the durability of the systems, electrical conductivity was checked before and after the tests. The results showed changes in resistance values after individual tests and during contact with harmful gases. Particularly noticeable are the differences between samples with embroidery and samples with inkjet paste applied. It was shown that the selected materials are suitable for the intended application, and selected modifications together with conductive materials show proper functioning in detecting harmful gases. This project demonstrates the possibility of creating chemical sensors based on printing techniques using carbon printing pastes and embroidery with a metal thread with silver on a textile substrate. Possible applications considering health and environmental aspects are presented. Full article

Photovoltaic double-skin glass is a low-carbon energy-saving curtain wall system that uses ventilation heat exchange and airflow regulation to reduce heat gain and generate a portion of electricity. By developing a theoretical model of the ventilated photovoltaic curtain wall system and conducting numerical simulations, this study analyzes the variation patterns of the power generation efficiency of photovoltaic glass for different inclination angles, seasons, thermal ventilation spacing, and glass transmittance in the photovoltaic double-skin curtain wall system. The results indicate a positive correlation between the surface temperature of photovoltaic glass and both ground temperature and solar radiation intensity. Additionally, photovoltaic power generation efficiency is generally higher in spring and autumn than in summer and winter, with enhanced power generation performance observed. At an inclination angle of 40°, photovoltaic panels receive optimal solar radiation and, consequently, produce the maximum electricity. Furthermore, as the ventilation spacing increases, the efficiency of power generation initially rises, reaching a peak at approximately 0.4 m, where it is 0.4% greater than at a spacing of 0.012 m. For a photovoltaic glass transmittance of 40%, the highest photovoltaic power generation efficiency is 63%, while the average efficiency is 35.3%. This has significant implications for the application and promotion of photovoltaic double-skin glass curtain walls. Full article

Circuit simulators are fundamentally used for solving electric circuit problems with different degrees of complexity in which node voltages and branch currents are the unknowns. This is fully understandable since they were originally created for this specific task. However, behind the curtains, powerful simulation engines based on a variety of numerical techniques operate so as to always comply with Kirchhoff’s current and voltage laws. In this paper, it is shown how a simple circuital configuration, referred to as the elementary solver, consistent in two behavioral current sources in series, can be used to solve mathematical problems that go beyond electronics. Of course, the intention is not to substitute mathematical packages with well-proven calculus capacity but to increase the scope of circuit simulators for their application in other areas of research or simply for educational purposes. It is worth mentioning that no special programming skills are required (except a basic knowledge of the available tools and language) and, furthermore, that the user can operate exclusively in a graphical environment. It is shown, throughout a series of selected examples, how the method of elementary solvers (MES) works, providing a new and practical dimension to the applicability of circuit simulators. Full article

The development of high-rise buildings worldwide has given rise to significant concerns regarding their excessive electricity consumption. Among the various categories of high-rise structures, hotels used for business and conferences stand out as particularly extravagant in their energy use. The consequence arising from excessive energy usage is an escalation in carbon emissions, which is a primary driver of global warming. Therefore, this study aims to investigate the energy use intensity (EUI) of a hotel building located in Jakarta, Indonesia. In order to improve energy performance, this study explored various options for renovating the building envelope, such as incorporating insulation and a roof covering, as well as implementing building-integrated photovoltaics (BIPV). The building envelope renovations demonstrated a notable reduction in energy use by 15.8–27.7% per year. BIPV, such as curtain walls and double-skin façades, generated an energy use reduction of 4.8–8.6% per year. Remarkably, by combining the two approaches (i.e., adding insulation and a roof covering in the building envelope and adopting BIPV as double-skin façades), the potential reduction in energy use reached up to 32.2% per year. The findings can assist decision-makers in developing building renovation strategies for high-rise buildings while considering energy conservation. Full article

During the construction of a diversion tunnel, geological problems often include faults, fragile strata, hard rock formations, karst landforms, etc., which may have adverse effects on the excavation and construction of the diversion tunnel. Based on the analysis of the engineering overview, this study designed a new construction technology for the excavation of water diversion tunnels in hard rock layers and high-karst areas. Based on tunnel seismic prediction (TSP) technology to achieve advanced geological prediction, combined with actual geological conditions, construction difficulties are analyzed. Then, detection technology is used to collect two-way travel time, amplitude, and waveform data. By processing and analyzing the detection image, the spatial orientation and length of the main tunnel during the construction of the diversion tunnel are calculated. After completing the construction ventilation and wind, water, and electricity layout, the excavation construction procedure is designed. In the specific excavation design, the tunnel curtain excavation technology, tunnel body excavation and support technology, excavation grouting technology, important unfavorable geological tunnel section excavation technology, upper/lower flat section excavation technology, upper/lower curved section excavation technology, and vertical shaft section excavation technology were elaborated. Finally, a plan was made for the reuse process of slag material and a construction quality control system was established. During the testing process, it was found that the antidamage coefficient of the side wall was above 0.9 after using the technology described in this article. Therefore, it indicates that the excavation construction technology designed in this article can ensure the support capacity of the side wall of the diversion tunnel, which is suitable for the excavation of the main tunnel during the construction of the diversion tunnel. Full article

This study utilizes a simplified two-dimensional time-dependent computational fluid dynamic (CFD) model to compare the performance of single- and two-layer air curtains in an open-type multi-deck refrigerated display cabinet. Two layers of air curtain generate a more effective invisible barrier from ambient air impact that can reduce electrical energy consumption and maintain a uniform temperature distribution within the cabinet. The CFD model of a refrigerated display cabinet was validated by the experimental data. The results showed a two-layer air curtain advantage over a single air curtain. Electrical energy consumption decreased by 18.5%, and the average temperature of the test products decreased from 5.75 °C to 5.17 °C. The results obtained are important for cabinet design to improve the quality of product storage and reduce energy consumption. Full article

Recommendations on the selection of air curtains and the calculation of their parameters for livestock premises in cattle management farms are made. The air curtain functioning principle is analyzed from the air jet theory point of view. The block diagram and modular design of air curtains with a variable air jet direction vector and with controlled slit width are designed. Laboratory tests of the newly designed air curtain structure are performed in accordance with the microclimate requirements for the cattle management farm premises. Based on the experimental results, the major air curtain parameters are calculated for the range from 10° to 60° of angle α between the direction of the air jet outward from the air curtain slit and aperture plane, and for the air curtain slit width b₀ in the range from 0.05 m to 0.15 m with the account of the wind speed V_w variations. Calculated values for amounts of energy that have to be consumed to ensure the required air jet velocity, in the output from the air curtain, and those for the quantity of thermal energy required to heat the air supplied to the air curtain, depending on the angle α and on the slit width b₀, can be helpful for selecting the power capacity of both the air curtain fan and electric heater. A block diagram of the air curtain control for cattle management farm premises is designed, enabling automatic control of the airflow rate, the angle of the air jet output from the air curtain slit, and the temperature of the heated air supplied to the air curtain, considering particular climate conditions. According to the preliminary estimate, applications of the newly designed air curtain will make it possible to reduce the energy consumed to maintain the required microclimate conditions in cattle management premises by 10% to 15% in the cold period. Full article

The problem of global warming has become a major global concern, and reducing greenhouse gas emissions is crucial to mitigate its effects. Photovoltaic power generation is clean, low-carbon energy. Photovoltaic products can convert solar energy into electricity, reducing CO₂ emissions to an extent. This paper introduces the life cycle evaluation theory to assess the carbon emissions of photovoltaic curtain walls. PVsyst software allows for the simulation and calculation of power generation under different influencing factors, which provides valuable information about the carbon reduction potential of photovoltaic curtain walls. The evaluation of carbon emissions and their influencing factors using grey correlation analysis further enhances the understanding of the benefits and limitations of photovoltaic curtain walls. According to the results of grey correlation analysis, this paper concludes that the degree of various influencing factors on carbon emission of a photovoltaic curtain wall under different scenarios in descending order is as follows: orientation, location, inclination, shadow occlusion, and seasonal changes. The research findings of this paper provide a theoretical reference for the future development and application of photovoltaic curtain walls. By demonstrating the carbon reduction potential of this technology, this study contributes to promoting the adoption of photovoltaic curtain walls as a sustainable solution to mitigate the effects of global warming. Full article

Electrostatic curtains can be simple and yet efficient devices to manipulate micronized particles on flat surfaces. This paper aims to investigate the motion of a 60 µm dielectric particle on the surface of a standing-wave conveyor. The study is based on a numerical model that accounts for the many forces that could potentially influence the particle motion. For that purpose, a numerical calculation of electric field and particle movement was carried out. The particle position above the curtain surface is obtained by a resolution of the dynamic equations using the Runge–Kutta method. The electric field distribution in the space above the curtain is obtained by a finite element calculation of the Laplace equation. The simulation results demonstrated a net dependence of the particle trajectory and movement modes on applied voltage frequency. Overall, low frequencies, typically below 50 Hz, allow for higher levitation and better displacement of the particle over long distances. Conversely, higher frequencies significantly reduce levitation and displacement distance. Moreover, at higher frequencies (around 500 Hz), the particle can vibrate between electrodes without any displacement at all. It is then inferred that low frequency is needed to better carry particles using a standing-wave curtain. Full article

Root zone heating can solve the problems associated with the yield and decline in the quality caused by low-temperature stress in cucumber during winter and early spring. An experiment was performed to investigate the effects of different heating methods on the root zone temperature, growth and photosynthetic characteristics, fruit quality, and yield of cucumber. Using traditional soil cultivation (CK1) and sand cultivation (CK2) in a greenhouse as the controls, four heating treatments were set up: soil-ridge sand-embedded cultivation (T1), water-heated soil cultivation (T2), water-heated sand cultivation (T3), and water-curtain and floor-heating cultivation (T4). The results indicated that heating treatments T2 and T4 had better warming and insulation effects than the other treatments during both day and night, with an average temperature increase throughout the day of 0.8–1.2 °C compared with CK1. The chlorophyll content of leaves under the T2 and T4 treatments increased, and the photosynthetic rate and the overall plant growth were significantly higher than in the other treatments. Compared with the control, the fruit yield increased most significantly under the T2 and T4; the soluble sugar, soluble solids, and Vc contents in the fruit increased; while the nitrate content in the fruit decreased, effectively improving the fruit’s quality and yield. It was finally determined that the T2 and T4 heating treatments are the most effective in solving the low-temperature problem. Moreover, as T2 consumed relatively more electricity, the use of a water-curtain and floor-heating system in winter and spring should be considered in order to boost the yield and improve the quality. Full article

Rough processing of iron ore employs dry methods which means that equipment is tuned to process large particles, but fine magnetic material less than a few tenths of a millimeter in size is not separated as efficiently. The relevance of this study is determined by the fact that dry beneficiation waste contains recoverable iron-bearing magnetite of commercial value. Commercial justification of waste beneficiation is associated with mining and grinding costs that are already included in the prime cost of the commercial concentrate. The future of tailings retreatment prospects depends on technology and efficiency of the employed equipment, the development of which is the subject of this paper. At first stage, fine iron is recovered by air sizing, with pitched curtain air classifiers embedding simple design and high performance. Powder materials were magnetically separated by a manufactured drum-type separator in which, to increase the separation efficiency, the process was performed at increased drum rotation speeds using $Nd$-$Fe$-B magnets and a drum made of electrically non-conductive materials. The separator performance was determined for various rotation speeds of the drum. Research has proven that a multi-stage magnetic separation with a consequent increase in drum rpm is reasonable. A new cascade separator was manufactured and tested for this purpose. It is shown that iron-containing ore tailings beneficiation is optimal without any additional grinding. Full article

The construction of reservoir dams has changed the environment and natural properties of the river course, and deep-water reservoirs present an obvious phenomenon of thermal stratification. Low-temperature outflow water in spring and summer will have a negative impact on the downstream ecological environment. Therefore, it is necessary to take selective withdrawal measures to regulate low-temperature outflow water. The temperature-control curtain project has the advantages of low cost, convenient construction and wide application. Based on the topographic data, a laboratory test model for regulating outflow temperature by a temperature-control curtain is established. A high-power electric heating system is adopted to form a nonlinear thermal stratification. The accuracy of the test data is verified by the prototype observed water temperature. The main parameters affecting the outflow temperature are investigated, including thermal stratification, flow height above the temperature-control curtain, water level, and discharge flow. The results show the following: firstly, the outflow temperature mainly depends on the thermal stratification, decreases with the increase of water level, and increases with the increase of discharge flow; secondly, the effect of a temperature-control curtain on improving the outflow temperature is directly related to the thermal stratification in different months, and the improvement effect is better in spring and summer; finally, the improvement effect increases with the decrease of flow height above the temperature-control curtain, increases with the increase of water level, and decreases with the increase of discharge flow. Full article