This paper presents an investigation on the influence of structural imperfections on the ultimate load capacity of steel welded beam-columns with class 4 cross-section under elevated temperatures. This is done by considering different amplitudes for the global and local (plate) imperfections, and different residual stresses distributions available in the literature. To this purpose, a geometrically and materially non-linear finite element model using Abaqus software has been used to determine the buckling resistance of a steel welded beam-column at elevated temperatures, using the material properties of EN1993-1-2. The imperfection sensitivity of beam-columns is reported: the influences of the amplitudes of the geometric imperfection and the patterns of the residual stress on the load capacity are compared.
Authors:Evjola Spaho, Aleksandër Biberaj, and Ares Tahiraga
Recently, low power wide area networks are attracting a lot of attention by the research community. They are wireless technologies characterized by large coverage area, low bandwidth and long battery life. One of these low power wide area networks technologies, the long range wide area network, can be used for different monitoring applications for health, agriculture, traffic, smart city.
In this paper, different simulations and experiments are conducted to implement a low-cost long-range wide area network environmental monitoring application for Tirana city in Albania. Simulation and experimental data are compared and similar results were obtained. In the low-cost implemented system, the gateway can communicate with the sensors placed in strategic positions with long distance covered also using Radio Mobile software.
Authors:Jakub Mydla, Andrej Šoltész, and Martin Orfánus
The contribution is dealing with run-off conditions on the lower part of the Ondava River as the capacity of the river bed is insufficient at high flow rates. The reason for the proposed research was the flood situations when protection dikes were breached. For mathematical modeling of flood wave progress, the HEC-RAS software has been applied coupling 1D and 2D modeling procedures. Results of the mathematical model of the surface water level regime in the Ondava River were compared with measured values and afterwards it was used to design further flood protection measures utilizing the existing drainage channel system and pumping stations, as well.
Authors:Bintul Zehra, Ali Salem, Souphavanh Senesavath, Saied Kashkash, and Zoltan Orban
Concrete is the most widely used construction material in the world. Over ten billion tons of concrete are being produced each year resulting in exhaustion of natural materials and an enormous carbon footprint. One of the primary goals of concrete technology today is to reduce the use of Portland cement and natural fine aggregates by partially replacing them with various waste materials and by-products of industrial processes. The paper summarizes the results of a study where the partial replacement of river sand and Portland cement was successfully applied using steel slag aggregate, silica fume and glass waste.
In this work, the thermal performance of using hybrid nanofluid of Ceria oxide and multi-walled carbon nanotube-based MOL 68 in the receiver tube of parabolic trough collector is simulated numerically. The influence of using this nanofluid under various volume concentrations and different Reynold numbers is solved numerically using computational fluid dynamics. The turbulent model's analysis is carried out based on k–ϵ re-normalization group and employed to find the Nusselt number and the heat transfer coefficients. The model results were validated with the previous correlation, which were used to evaluate the Nusselt number. The results showed that hybrid nanofluid enhances the heat transfer characteristics of the parabolic trough collector in comparison with the base fluid. Furthermore, even better heat transfer characteristics can be achieved with an increased volume concentration of the modified nanofluids.
Authors:Hui Cao, Anna Mária Tamás, and Gergely Sztranyák
With the reform of China's childbirth policy in recent years, a unique baby boom phenomenon has emerged, and the new-born baby has increased rapidly in China. In the process of transformation and development of contemporary cities, a complex urban environment has a significant impact on psychology and physiology. The past kindergarten architectural aesthetic experience can no longer adapt to the social development needs. Thus, how to realize the sustainable development of kindergarten architecture has become a social problem that needs to be solved urgently. In the context of Environmental Psychology, this paper investigates the construction mode of experiential kindergarten architecture and tries to explore a new paradigm of educational architecture design in China for the future.
The laser tracker is a widely used instrument in many industrial and metrological applications with high demand measurement accuracy. Imperfections in construction and misalignment of individual parts deliver systematic errors in the measurement results. All error sources need to be identified and reduced to the minimum to achieve the best possible accuracy. The paper summarizes error sources of the laser tracker without beam steering mirror with emphasis on error modeling. Descriptions of error models are provided for the static and kinematic type of measurement.
The city of Prishtina has constantly been changing in urban, architectural, and technological terms. This has political, ecological, economic, and cultural consequences, especially in the downtown area, where higher-density, taller office buildings and commercial spaces and even more congested residential areas are planned. In this study, the Urban Gastro-Lounge is taken as an example of an adaptive reuse strategy for a whole building or its interior. This example of adaptive reuse aims to revive urban and architectural areas as a way of promoting the sustainable development of the city in terms of its general formal architectural morphology. The Urban Gastro-Lounge is an excellent example of this approach and is worthy of being considered a particularly useful intervention.
Authors:Amin Damanjani, Mohamad Hosseini Abardeh, Azita Azarfar, and Mehrdad Hojjat
Microgrids (MGs) are capable to work at different operation modes, namely grid-connected or islanded, which make a significant change in the network fault current level. These changes may lead to problems and should be detected fast to do the proper protection actions accordingly and prevent blackouts. Moreover, some island detection methods suffer from the drawbacks of high computation burden and time-consuming procedure of training data to detect the islanded mode. For this purpose, in this paper, a faster and less computation burden island detection scheme without the need for training data is proposed which detects the islanded mode by analyzing the fault current data obtained from a continuous sampling using the phasor measurement unit (PMU). The sampled data are utilized in the fuzzy c-means (FCM) clustering to determine the network operation mode. The proposed scheme works in two phases. In the offline phase, the root mean square (RMS) of the current amplitude for islanded mode is determined, and in the online phase, the center of the measured data is compared to the RMS value to detect the MG operation mode at a decision making procedure. It is proved that the proposed island detection scheme is an applicable technique for detecting the islanded mode in MGs.
In recent years, the importance of nanomaterials in food science, medicine, etc. has been increasing quickly. Herein, organic and inorganic red selenium nanoparticles synthesised by the reduction of sodium selenite with chemical and biological reducing agents. Grey hexagonal form in aqueous and powder was assembled at a high temperature of 85 °C for 10 min. Also, selenium enriched yogurt powder was made that contained about 2,000 mg kg−1 selenium, 93.8% of which is in nano form with a size of 50–500 nm. The synthesised nanoparticles were characterised by Dynamic Light Scattering Particle Size Analyzer (DLS), X-ray Diffraction Analysis (XRD), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). The prepared SeNPs could be promising additive for a wide range of applications.