Papers by Keyword: Experimental Study

Abstract: Solar desalination efficiency can be significantly altered by combining several approaches to improve evaporation rate. The objective of this research is to find a way to make solar stills (SS) more efficient by combining evacuated tube solar collectors, blue metal stones, and corrugated fins. An investigation into a six-tube evacuated solar collector was conducted to increase the system's evaporation rate. Corrugated fins were thought of to rise the surface area of heat transfer between the water and absorber. Blue metal stone was proposed to keep the water at a maximum temperature even when solar radiation is minimal. Separate displays of the cumulative distillate output (DO) numbers and hourly values for each time period provide a comprehensive view. Based on the findings, the peak period for DO moves from 1 p.m. on a sample day in May 2024, which is six months into the project. In comparison to CSS, MSS temperature values are over 55 °C higher at the peak and nearly 26 °C higher on average. On top of that, the total DO during the day can reach 2.64 to 6.82 L, while at night it rises from 0.067 to 0.96 L. In addition, there is a 146.3% improvement in the average DO during the six months, going from 3.02 to 7.22 L. Additionally, MSS is 0.43₹ per liter and CSS is 0.47₹ per liter, in that order. The net amount of carbon dioxide reduction achieved by modified solar stills was approximately 2.44 times greater than that of conventional solar stills.

Abstract: A systematic experimental study is conducted on floating field rings (FFR) incorporated into 4H-SiC junction barrier Schottky (JBS) diodes across four voltage ratings 650, 1200, 1700 and 3300V, in pursuit of highly efficient FFR designs. 30 designs of FFR in 3 categories are studied for each voltage rating, and the measured breakdown voltage (Vbr) of JBS divided by ring system width (W) is taken as the figure of merit (FOM) of each design. The influence of ring spacing, ring width and number of rings on Vbr is studied in detail. It is found that the initial ring spacing (S1) is critical in determining the highest Vbr achievable by a certain design, and its optimum value increases as voltage rating increases. TCAD simulation verifies the importance of S1. For designs with a small ring system width, subsequent ring spacing can also become important. Ring width does not have a definitive effect, and Vbr saturates beyond a certain ring number. The design with the highest Vbr may not render the highest FOM. Even style designs with appropriate ring spacings can be advantageous likely due to less susceptibility to variation of field oxide charge, and more tolerance to fabrication error, as well as ease of design.

Abstract: Filling steel tubes with coral concrete to form concrete filled steel tube composite structures for compression members can compensate for its low aggregate strength. In order to demonstrate the reinforcement mechanism of coral concrete hoop under steel tube restraint and to propose the strength theory under the hoop effect, it is necessary to obtain the theoretical analysis based on the theory of triaxial compressive bearing theory of normal concrete. Therefore, starting from the failure mechanism of coral concrete under triaxial compression, the hoop reinforcement mechanism of coral concrete under different lateral pressure conditions is studied analytically. By the axial compression bearing capacity comparative test between normal concrete and coral concrete under steel tube restraint, comparative relationship between lateral pressure and circumferential strain is calculated and the conditions for taking values are acquired, which lays the foundation for the calculation theory of the compressive bearing capacity of it.

Abstract: Earth-based materials (EBM) provides a valuable avenue for improving thermal comfort, energy consumption, indoor air quality and humidity regulation. However, in the literature, very few studies have addressed hygrometric characteristics of shell huts in EBM from the far north region of Cameroon. The use EBM is hampered by the non-availability of databases related to their intrinsic properties and through unfamiliarity of their behavior over time. In the meantime, these shell huts in EBM are known for their moisture which regulates properties and thus contributes to the comfort of their occupants. This study aims to determine experimentally the adsorption/desorption isotherms at 30, 40 and 50 °C of the straw earth material carried out by the static gravimetric method for eight saturated salt solutions (LiCl, MgCl2, Mg(NO³)², NaBr, IK, NaCl, KCl and K²SO⁴). The experimental curves obtained for absorption / desorption show that for a given water activity, the equilibrium water content W_eq increases inversely with temperature (i.e. decreases with increasing temperature, and vice versa). In addition, the absorption curve does not overlap with the desorption curve. As a result, these shell huts in EBM display interesting humidity regulation characteristics.

Abstract: Methods for determining the actual limit of fire resistance of reinforced concrete building structures in case of fire are analyzed. On the basis of the offered methods the technique which gives the chance to receive data of temperature distributions on a surface of a fragment of a wall and in its section is created. The method of conducting a fire test to calculate the limit of fire resistance of a small fragment of the load-bearing wall and verify the reproducibility of experimental data is described. The distribution of temperatures over the entire area of the fire furnace, the studied fragment was checked and the obtained results were analyzed. According to the results of this work, the following was established: the aim of the work was to obtain the results of temperature distributions on the surface, in the points of integration in the cross sections of fragments of reinforced concrete walls for further calculation of their fire resistance limit and check reproducibility of experimental data. It is established that the temperature obtained as a result of the fire test corresponds to the standard temperature of the fire and this method of fire test to determine the temperature distributions of a small fragment of the load-bearing wall in fire conditions is acceptable for use. The error between the experimentally determined and theoretically calculated limit of fire resistance is not more than 3%.

Abstract: A pin-connected joint, which was intended to accommodate a certain in-plane rotation and resist the shear forces, was introduced in this paper. Pinned-connections were applied on Truss-Column joints to support the heavy-loaded floors and roofs in a long-span steel structure. The Pinned-connection was designed in accordance with European code, and compared with other standards such as America standard and Australia standard. To better understand the behavior of materials and structure of this pin-connection structural system, four specimens, including two full-scale pin-connections and two truss connections, were tested to investigate the performance under both monotonic and cyclic loads. The load–displacement curves, hysteretic curve and ultimate loads were obtained, and the failure mode, capacity and ductility were discussed. The experimental and numerical results indicated that the pin-connection behaved good ductility, load transfer ability and capacity.

Abstract: The paper presents compression tests of stocky and slender masonry pillars strengthened in bed joints with PBO fibres and an inorganic matrix. Five stocky pillars and four slender pillars were tested under static loading. Physical models were prepared using lime mortar similar to that used in historical structures. Fibres were applied in the grooves that were made after the mortar setting period in order to recreate real-world conditions. One of the models was subjected to preloading before the strengthening was applied. The failure modes, load-bearing capacity, cracking stresses, stiffness and deformations (longitudinal and transverse) were all determined through experimental testing. Strengthening effectiveness in terms of the increase in load-bearing capacity and stiffness, as well as anti-cracking was determined on the basis of the experimental results. The results obtained for the stocky and slender pillars were also compared, indicating the influence of slenderness on strengthening effectiveness. Special attention was also paid to failure modes and the interaction of the PBO fibres with the bed joint. Methods that strengthen pillars in their bed joints using PBO fibres increase their load-bearing capacity, stiffness and cracking resistance, while maintaining a satisfactory visual appearance which is especially important in heritage structures.

Abstract: Bio-based materials are a promising tracks that offer thermal and environmental performances in order to reduce the consumption of energy and of non-renewable resources. For this purpose, in a previous study, the LGCGM worked on the development of Washing Fines Hemp composites (WFH) and characterized them on multiphysical points of view. Such materials show low thermal conductivity and high moisture buffer ability. In order to characterize their hygrothermal behavior at wall scale, a test wall is set up in an air-conditioned bi-climatic test room to simulate indoor and outdoor climates. This paper investigates the characterization of hygrothermal behavior of Washing Fines Hemp wall under typical Tunisian summer climate. It consists in an experimental study, supplemented by numerical simulation performed with WUFI Pro V6.5 software. The experimental hygrothermal response of the wall to such solicitations is analyzed from the temperature and relative humidity kinetics at several positions in the wall and from temperature and vapor pressure profiles. It shows that for daily cycles the two thirds of the thickness of the wall on the exterior side are active, as well regarding heat and moisture phenomena. More sorption-desorption phenomena are highlighted. The numerical results are consistent with experimental data for temperature and underestimate vapor pressure in the inner part of the wall.

Abstract: The knowledge of the complex biomechanical behaviour of the injured knee joints is of paramount importance in various clinical situations. A review of the biomechanical effects of meniscal tears based on experimental and finite element analysis has not been reported in the literature. The objective of this study is to present a review of experimental and finite element investigations on the consequences of meniscal tears such as longitudinal, radial, horizontal cleavage and root tears in the medial and lateral menisci. It is found that larger longitudinal tear in the medial meniscus has a significant impact on the magnitude of strain in the meniscus associated with a dramatic increase in CP in the tibial cartilage. Also, the untreated fragment of the torn meniscus leads to a significant rise in contact pressure in the cartilage resulting in the progressive degeneration of the cartilage surface. The radial tears in the lateral meniscus of more than 66% width and those in the medial meniscus of more than 75% width result in a substantial increase in the contact pressure in the cartilage compared to that in the intact knee joint. The root tears in the menisci demonstrate a significant influence on the biomechanical response of the knee joint. The results of finite element analysis studies are compared with experimental findings. Finally, some recommendations for future work are proposed to predict the realistic biomechanical response of the knee joints with meniscal tears. The results of this study present a rationale that could help surgeons in making clinical decisions when managing patients with meniscal tears.

Abstract: This study aimed to investigate the influence of longitudinal steel embedded tubes located at the center of the column cross-section on the behavior of reinforced concrete (RC) columns. The experimental program consisted of 8 testing pin-ended square sectional columns of 150×150 mm, having a total height of 1400 mm, subjected to eccentric load. The considered variables were the steel square tube sizes of 25, 51 and 68 mm side dimensions and the load eccentricity (50 and 150) mm. RC columns were concealed steel tubes with hollow ratios of 3%, 12% and 20% depending on tube sizes used. The experimental results indicated an improvement in the overall behavior of eccentric columns when steel embedded tubes are used. The maximum gain in strength was about 59% for the hollow ratio of 20% with e/h=1. The test results show that the inserted steel pipe improves strength, ductility and enables these columns to absorb more energy than a similar solid column.