نشریه مهندسی عمران فردوسی
سال سی و چهارم شماره 2 (تابستان 1400)

Identification of infrastructure damage in the early stages is one of the most fundamental requirements through the maintenance process. In order to identify damages in the process of Structural Health Monitoring, numerous methods have been developed, including Neural Network (NN) Damage Identification Techniques, Time Series Damage Identification Techniques, Frequency Response Damage Identification Techniques, Force Spectrum Density Damage Identification Techniques, and Wavelet Damage Identification Techniques. The conventional structural health monitoring procedure depends on a comparison of undamaged primary structural data to the affected structural data. Comparative algorithms to indicate the location of damage based on the structural data has a significant effect on the structural health monitoring method performance. Therefore, a damage detection algorithm is the most important step in identifying damage in the structural health monitoring procedure. In this paper, a damage identification algorithm based on the relative wavelet entropy method is proposed for the structure. Using the definition of the discrete wavelet transform with wavelet entropy form the base of the proposed algorithm for damage detection to support the method efficiency. The proposed method is capable of identifying several sites of damage and is used as an effective method compared to other methods of damage detection.

The purpose of this study is to determine the appropriate percentage of RAP and cement in the stabilized base in such a way that the durability and economics of the pavement are considered simultaneously. Therefore, compressive and tensile strength was obtained in different percentages of RAP including 0%, 40%, 60%, and 80%, and indifferent percentages of cement including 3%, 5%, and 7%. The structural design of the Pavement was further determined under 10, 20, 35, and 50 million ESALs. By establishing the relationship between the percentages of RAP, percentage of cement, and moisture sensitivity index (TSR) as an effective parameter in durability, and the cost of paving at different loads, a simultaneous cost-durability equation of pavement was formed. Finally, based on the optimization technique, the optimal percentage of RAP and cement to achieve the expected durability (TSR = 70) was determined. Hence, the optimum cost, which is a function of the loading level, was obtained in the amount of 29.6% of RAP, 4.16% of cement, and in the minimum loading level. The results can be appropriately approximated in the design of durable and economical pavement structures Contains a stabilized base with cement and various amounts of RAP.

This study was intended to estimate resistance to flow through velocity profile characteristics in a cobble-gravel bed river with 3D-Pool-Riffle bedforms and irregular distribution of flexible-submerged vegetation patches. To this end, a total of 39 velocity profiles consisting of four independent sections of Padena Marbor River have been studied. The finding showed that the depth of validity logarithmic law depends on the location of measurements including both inlet and outlet of the Pool. The predominant form of deviation from this law is frequently observed upwards at the inlet of the Pool and downwards at the outlet of the Pool and Riffle, which has a direct effect on the estimation of resistance to flow. Moreover, the results of resistance to flow revealed that the coefficients of resistance to flow are exponentially related to blockage area with a correlation coefficient greater than 0.8. Therefore, blockage area can be a suitable parameter in estimating resistance to flow in cobble-gravel bed rivers with 3D bedforms and irregular vegetations patches.

The uniaxial compressive strength parameter is an important and key parameter in geomechanical engineering that is used in rock engineering classification, study of rock fracture criteria and in the design stage of many construction and mining projects. In many cases, due to the lack of access to quality cores, determining these parameters in the laboratory is associated with many difficulties, and often this parameter is indirectly estimated from regression relationships that these relationships are not very accurate. The aim of this study is to use the new meta-heuristic algorithms of gray wolf (GWO) and fruit fly algorithm (FFOA) to indirectly estimate uniaxial compressive strength. To achieve this goal, data from 124 granite rock samples from the Selangor freshwater transfer tunnel project in Malaysia, have been used. Finally, to evaluate and validate the models obtained by intelligent algorithms, the indices of statistical are used. According to the results obtained in this paper as well as the validation of the models, the predicted values ​​of uniaxial compressive strength are very close to the real values ​​of the region, indicating the low error of the models in indirect estimation. In addition, in this paper, sensitivity analysis was performed on the effective parameters in estimating uniaxial compressive strength. The results showed that the return values ​​of Schmidt hammer (Rn), among other input parameters, have the greatest effect on uniaxial compressive strength.

Petroleum wastewater contains a wide range of hard biodegradable pollutants that are not treated by conventional treatment methods. In this study, the photocatalytic degradation of organic pollutants in the wastewater of Petroleum were investigated using new Fe-ZSM-5@TiO2/Ag synthetic nano-photocatalyst. Synthesis of nano photocatalyst was done by immobilizing iron on zeolite to improve ZSM-5 structure and then TiO2 and Ag coated to reduce the band gap energy. Physical and chemical properties of the materials determined by XRD, SEM, FT-IR and BET analyzes. TiO2 in the anatase phase was shown in synthetic nano-photocatalyst using XRD analysis. The uniformity of the nanoparticles was also revealed in the SEM images, which showed that the TiO2 and Ag particles were well located on the surface of Fe-ZSM-5. Experimental procedure was done using experimental method by response surface method (RSM). The effects of main parameters containing pollutant concentration, photocatalyst nanoparticle concentration, pH, reaction time, radiation wavelength and different photocatalysts were performed in a batch pilot. The results showed that at pH=5 and the photocatalyst concentration of Fe-ZSM-5@TiO2/Ag equal to 2 g/L under UV-A irradiation at 54 watts and 240 min time the best COD removal performance was about 83%.

In non-prismatic compound channels due to the mass and momentum exchange between the main channel and floodplains, the flow interaction between channel sub-sections is higher than prismatic compound channels. As a result, in this form of channels, the study of apparent shear forces create at the vertical interface between the main channel and floodplains are much more complex. In the present research, the velocity and boundary shear stress distributions were measured at different sections along the skew part of the flume. Also using the experimental data and the momentum equations the flow interaction between the main channel and floodplains have been investigated. Measurements have been performed for two skew angles of 11.31 and 3.81 degrees and three relative depths of 0.2, 0.3 and 0.4. Investigations indicate that the flow interaction between the main channel and the converging floodplain is generally greater than the flow interaction between the main channel and the diverging floodplain. Also, the side slope of the floodplains, has increased the amount of apparent shear force at the interface between the main channel and floodplains.