Indoor Climate Modelling and Economic Analysis Regarding the Energetic Rehabilitation of a Church

Background: The aim of our study was to identify an optimal heating system for the analyzed church. We also evaluated the energy consumption of the existing system and of those proposed in order to choose the best heating system. Methods: We analyzed the current existing heating system, a mixed system (static heaters and hot air heating) in a Romanian heritage church, build in the 16th century, and we compared it with an underfloor heating system that has been mentioned in the literature as an alternative for church heating. We used a computational fluid dynamics (CFD) analysis of the indoor climate with two turbulence models (k-ε and k-ω). Results: Comparing the two heating systems through boxplot graphs, we could highlight pertinent conclusions regarding the temperatures and velocities of the measured air currents. Thus, of all the heating systems, the underfloor heating had the lowest temperatures, but the highest air velocities, in the churchgoers area, especially under the towers zone. Conclusions: We observed that the underfloor heating system was more efficient than the existing heating system (static heaters and hot air heating), ensuring heritage conservation and high thermal comfort to the churchgoers

Experimental Study on the Behaviour of Seismic Actions on a Flexible Glass-Reinforced Plastic Structure Used in Water Transport Pipes

This article presents the experimental results obtained by the testing an experimental model of water distribution which is flexible and above-head mounted on a seismic platform, and their validation in a theoretical manner, but also by the Finite Element Method, using the ANSYS simulation program. This type of system shown by the experimental model is desired to be used in practice not only in seismic areas, but also in the areas of heavy road transport, landslides, etc. thorugh the use thereof in the most stressed points of the network (hearth entry/exit, before/after an elbow, etc.) but also on long routes, at optimal distances. The results achieved are related to glass- reinforced plastic (GRP) pipes with a nominal diameter DN = 250 mm, but conclusions may be drawn starting from these to help future research where the mass of the earth is desired to be taken into account. The present results are comprehensive for buried pipes operated dynamically or seismically at low-medium intensity, as this type of earthquake occurs more and more often in Europe. The experimental tests in this article do not have the characteristics necessary for a high intensity seismic action (above 5° Richter)

Improved Recurrent Neural Network Schema for Validating Digital Signatures in VANET

Vehicular ad hoc networks (VANETs) allow communication between stationary or moving vehicles with the assistance of wireless technology. Among various existing issues in smart VANETs, secure communication is the key challenge in VANETs with a 5G network. Smart vehicles must communicate with a broad range of advanced road systems including traffic control and smart payment systems. Many security mechanisms are used in VANETs to ensure safe transmission; one such mechanism is cryptographic digital signatures based on public key infrastructure (PKI). In this mechanism, secret private keys are used for digital signatures to validate the identity of the message along with the sender. However, the validation of the digital signatures in fast-moving vehicles is extremely difficult. Based on an improved perceptron model of an artificial neural network (ANN), this paper proposes an efficient technique for digital signature verification. Still, manual signatures are extensively used for authentication across the world. However, manual signatures are still not employed for security in automotive and mobile networks. The process of converting manual signatures to pseudo-digital-signatures was simulated using the improved Elman backpropagation (I-EBP) model. A digital signature was employed during network connection to authenticate the legitimacy of the sender’s communications. Because it contained information about the vehicle on the road, there was scope for improvement in protecting the data from attackers. Compared to existing schemes, the proposed technique achieved significant gains in computational overhead, aggregate verification delay, and aggregate signature size

Numerical and Parametric Analysis for Enhancing Performances of Water Photovoltaic/Thermal System

Photovoltaic/thermal (PV/T) systems are innovative cogeneration systems that ensure the cooling of photovoltaic (PV) backside and simultaneous production of electricity and heat. However, an effective cooling of the PV back is still a challenge that affects electrical and thermal performance of the PV/T system. In the present work, a PV/T numerical model is developed to simulate the heat flux based on energy balance implemented in MATLAB software. The numerical model is validated through the comparison of the three-layer PV model with the NOCT model and tested under the operation conditions of continental temperate climate. Moreover, the effect of velocity and water film thickness as important flow parameters on heat exchange and PV/T production is numerically investigated. Results revealed that the PV model is in good agreement with the NOCT one. An efficient heat transfer is obtained while increasing the velocity and water film thickness with optimal values of 0.035 m/s and 7 mm, respectively, at an inlet temperature of 20 °C. The PV/T system ensures a maximum thermal power of 1334.5 W and electrical power of 316.56 W (258.8 W for the PV). Finally, the comparison between the PV and PV/T system under real weather conditions showed the advantage of using the PV/T

Fight against Future Pandemics: UAV-Based Data-Centric Social Distancing, Sanitizing, and Monitoring Scheme

The novel coronavirus disease-2019 (COVID-19) has transformed into a global health concern, which resulted in human containment and isolation to flatten the curve of mortality rates of infected patients. To leverage the massive containment strategy, fifth-generation (5G)-envisioned unmanned aerial vehicles (UAVs) are used to minimize human intervention with the key benefits of ultra-low latency, high bandwidth, and reliability. This allows phased treatment of infected patients via threefold functionalities (3FFs) such as social distancing, proper sanitization, and inspection and monitoring. However, UAVs have to send massive recorded data back to ground stations (GS), which requires a real-time device connection density of 107/km2, which forms huge bottlenecks on 5G ecosystems. A sixth-generation (6G) ecosystem can provide terahertz (THz) frequency bands with massive short beamforming cells, intelligent deep connectivity, and physical- and link-level protocol virtualization. The UAVs form a swarm network to assure 3FFs which requires high-end computations and are data-intensive; thus, these computational tasks can be offloaded to nearby edge servers, which employ local federated learning to train the global models. It synchronizes the UAV task formations and optimizes the network functions. Task optimization of UAV swarms in 6G-assisted channels allows better management and ubiquitous and energy-efficient seamless communication over ground, space, and underwater channels. Thus, a data-centric 3FF approach is essential to fight against future pandemics, with a 6G backdrop channel. The proposed scheme is compared with traditional fourth-generation (4G) and 5G-networks-based schemes to indicate its efficiency in traffic density, processing latency, spectral efficiency, UAV mobility, radio loss, and device connection density

Comparative Numerical Studies on the Structural Behavior of Buried Pipes Subjected to Extreme Environmental Actions

Globally, there are several critical infrastructure networks (water and gas networks) whose disruption or destruction would significantly affect the maintenance of vital societal functions, such as the health, safety, security, and social or economic well-being of people. They would also have significant local, regional, and national impacts as a result of the inability to maintain those functions, and would have similar cross-border effects. The main objective of this article is to investigate by comparative numerical studies the structural response of three types of buried pipes made of different materials, primarily steel, concrete, and high-density polyethylene, resulting from the impact of the environment through exceptional external actions, such as explosions at the surface of the land in the vicinity of the laying areas. The dynamic transient analysis of the equation of motion with the application of the explicit integration procedure was performed with the ANSYS numerical simulation program. This study allows designers to solve complex problems related to the quality of the laying ground of water networks to canals. The knowledge accumulated gives us the possibility to correctly specify the optimal economic and technical value of the ratio between the laying depth of pipes and their diameter, the importance of the radius ratio of the pipe and the thickness of its wall, and, importantly, the improvement of the quality of the foundation ground. Following the results obtained, it is estimated that the optimal economic and technical value of the ratio between the laying depth of the pipes (H) and their diameter (D) is 3, regardless of the material from which the pipe is made

Effect of Wind Direction and Velocity on PV Panels Cooling with Perforated Heat Sinks

The numerical modeling of the effect of wind direction and velocity over the air cooling of PV panels with heat sinks is realized. During the study, a random PV panel with typical characteristics was analyzed for three different wind directions—towards its back, towards its front and from the side. The analysis was realized on a fixed PV panel, oriented to the south, with an inclination of 45 degrees from the horizontal position. The accuracy of the numerical simulation was achieved by comparison with the experimental studies presented in the literature and by comparing the NOCT conditions. The numerical study is focused on different types of heat sinks attached to a typical PV panel. The fins were distributed both horizontally and vertically. A challenging task consisted in simulation of the real wind conditions around the PV panel by taking into account the entire air domain. The simulations were realized for air velocity vair from 1 m/s to 5 m/s, solar radiation of G = 1000 W/m2 and ambient temperature tair = 35 °C. The output parameters analyzed were the average temperature of PV panels and their power production. Although the lowest temperatures were achieved for the back wind, the cooling effect was more intense for the side wind. The other direction studied also determined the cooling of PV panels. The passive cooling solutions analyzed introduced a rise of maximum power production between 1.85% and 7.71% above the base case, depending on the wind direction and velocity

Effect of Wind Direction and Velocity on PV Panels Cooling with Perforated Heat Sinks

The numerical modeling of the effect of wind direction and velocity over the air cooling of PV panels with heat sinks is realized. During the study, a random PV panel with typical characteristics was analyzed for three different wind directions—towards its back, towards its front and from the side. The analysis was realized on a fixed PV panel, oriented to the south, with an inclination of 45 degrees from the horizontal position. The accuracy of the numerical simulation was achieved by comparison with the experimental studies presented in the literature and by comparing the NOCT conditions. The numerical study is focused on different types of heat sinks attached to a typical PV panel. The fins were distributed both horizontally and vertically. A challenging task consisted in simulation of the real wind conditions around the PV panel by taking into account the entire air domain. The simulations were realized for air velocity vair from 1 m/s to 5 m/s, solar radiation of G = 1000 W/m2 and ambient temperature tair = 35 °C. The output parameters analyzed were the average temperature of PV panels and their power production. Although the lowest temperatures were achieved for the back wind, the cooling effect was more intense for the side wind. The other direction studied also determined the cooling of PV panels. The passive cooling solutions analyzed introduced a rise of maximum power production between 1.85% and 7.71% above the base case, depending on the wind direction and velocity

Experimental Study on Airflow and Temperature Predicting in a Double Skin Façade in Hot and Cold Seasons in Romania

In the context of energy conservation and sustainable development, building design should take into account the energy efficiency criteria by using renewable energy sources. Double-skin facades (DSF) represent innovative energy-efficient techniques that have gained increasing interest worldwide. The present study reports the results of an experimental campaign performed on a full-scale double-skin façade using the in-situ measurement methodology. The thermodynamic behavior of the façade is studied under real exterior climatic conditions in Romania in hot and cold seasons, and performance indicators in terms of pre-heating efficiency and dynamic insulation efficiency were determined. Three summer periods are analyzed corresponding to the outdoor air curtain scenario for three ventilation modes in naturally or mechanically ventilated single-story DSF. Results revealed that the third ventilation scenario, which combines horizontal and vertical openings, gives the best efficiency of 71.3% in the double skin façade functioning. During the cold season, the channel façade behaved like a thermal buffer between the building and the exterior air, ensuring the thermal energy for partial or integral heating of the building

Experimental Study on Airflow and Temperature Predicting in a Double Skin Façade in Hot and Cold Seasons in Romania

In the context of energy conservation and sustainable development, building design should take into account the energy efficiency criteria by using renewable energy sources. Double-skin facades (DSF) represent innovative energy-efficient techniques that have gained increasing interest worldwide. The present study reports the results of an experimental campaign performed on a full-scale double-skin façade using the in-situ measurement methodology. The thermodynamic behavior of the façade is studied under real exterior climatic conditions in Romania in hot and cold seasons, and performance indicators in terms of pre-heating efficiency and dynamic insulation efficiency were determined. Three summer periods are analyzed corresponding to the outdoor air curtain scenario for three ventilation modes in naturally or mechanically ventilated single-story DSF. Results revealed that the third ventilation scenario, which combines horizontal and vertical openings, gives the best efficiency of 71.3% in the double skin façade functioning. During the cold season, the channel façade behaved like a thermal buffer between the building and the exterior air, ensuring the thermal energy for partial or integral heating of the building