Study on High-Temperature Oxidation Behaviors of Plasma-Sprayed TiB₂-Co Composite Coatings

Fadavi, Milad,Baboukani, Amin Rabiei,Edris, Hossein,Salehi, Mahdi The Korean Ceramic Society 2018 한국세라믹학회지 Vol.55 No.2

In the present study, $TiB_2-Co$ composite coatings were thermally sprayed onto the surface of a 304 stainless steel substrate using an atmospheric plasma spray (APS). The phase analysis of the powders and plasma-sprayed coatings was performed using X-ray diffractometry analysis. The microstructures of the coatings were studied by a scanning electron microscope (SEM). The average particle size and flowability of the feedstocks were also measured. Both $TiB_2-32Co$ and $TiB_2-45Co$ (wt.%) coatings possessed typical dense lamellar structures and high-quality adhesion to the substrate. The oxidation behaviors of the coatings were studied at $900^{\circ}C$ in an atmospheric environment. In addition, the cross-sectional images of the oxidized coatings were analyzed by SEM. A thin and well-adhered layer was formed on the surface of both $TiB_2-Co$ coatings, confirming satisfactory high-temperature oxidation resistance. The kinetic curves corresponding to the isothermal oxidation of the coatings illustrated a short transient stage from rapid to slow oxidation during the early portion of the oxidation experiment.

Application of neural networks and an adapted wavelet packet for generating artificial ground motion

Asadi, A.,Fadavi, M.,Bagheri, A.,Ghodrati Amiri, G. Techno-Press 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.6

For seismic resistant design of critical structures, a dynamic analysis, either response spectrum or time history is frequently required. Owing to the lack of recorded data and the randomness of earthquake ground motion that may be experienced by structure in the future, usually it is difficult to obtain recorded data which fit the requirements (site type, epicenteral distance, etc.) well. Therefore, the artificial seismic records are widely used in seismic designs, verification of seismic capacity and seismic assessment of structures. The purpose of this paper is to develop a numerical method using Artificial Neural Network (ANN) and wavelet packet transform in best basis method which is presented for the decomposition of artificial earthquake records consistent with any arbitrarily specified target response spectra requirements. The ground motion has been modeled as a non-stationary process using wavelet packet. This study shows that the procedure using ANN-based models and wavelet packets in best-basis method are applicable to generate artificial earthquakes compatible with any response spectra. Several numerical examples are given to verify the developed model.

Application of neural networks and an adapted wavelet packet for generating artificial ground motion

A. Asadi,M. Fadavi,A. Bagheri,G. Ghodrati Amiri 국제구조공학회 2011 Structural Engineering and Mechanics, An Int'l Jou Vol.37 No.6

For seismic resistant design of critical structures, a dynamic analysis, either response spectrum or time history is frequently required. Owing to the lack of recorded data and the randomness of earthquake ground motion that may be experienced by structure in the future, usually it is difficult to obtain recorded data which fit the requirements (site type, epicenteral distance, etc.) well. Therefore, the artificial seismic records are widely used in seismic designs, verification of seismic capacity and seismic assessment of structures. The purpose of this paper is to develop a numerical method using Artificial Neural Network (ANN) and wavelet packet transform in best basis method which is presented for the decomposition of artificial earthquake records consistent with any arbitrarily specified target response spectra requirements. The ground motion has been modeled as a non-stationary process using wavelet packet. This study shows that the procedure using ANN-based models and wavelet packets in best-basis method are applicable to generate artificial earthquakes compatible with any response spectra. Several numerical examples are given to verify the developed model.

Structural damage detection based on changes of wavelet transform coefficients of correlation functions

Sadeghian, Mohsen,Esfandiari, Akbar,Fadavie Manochehr Techno-Press 2022 Structural monitoring and maintenance Vol.9 No.2

In this paper, an innovative finite element updating method is presented based on the variation wavelet transform coefficients of Auto/cross-correlations function (WTCF). The Quasi-linear sensitivity of the wavelet coefficients of the WTCF concerning the structural parameters is evaluated based on incomplete measured structural responses. The proposed algorithm is used to estimate the structural parameters of truss and plate models. By the solution of the sensitivity equation through the least-squares method, the finite element model of the structure is updated for estimation of the location and severity of structural damages simultaneously. Several damage scenarios have been considered for the studied structure. The parameter estimation results prove the high accuracy of the method considering measurement and mass modeling errors.

ABO Blood Groups in Oral Cancer: A First Case-Control Study in a Defined Group of Iranian Patients

Mortazavi, Hamed,Hajian, Shima,Fadavi, Elnaz,Sabour, Siamak,Baharvand, Maryam,Bakhtiari, Sedigheh Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.3

The ABO blood group has been recently proposed to influence development of oral cancer. The aim ofthis study was to evaluate the association between the type of ABO blood group and oral cancer. In a case-control study, 104 patients with oral cancer were compared with 90 blood donors without cancer as controls. Data regarding the patient demographics, blood groups, Rh status, cancer characteristics and oral habits were also compared between two subgroups of squamous and non-squamous oral cancers. For statistical analysis, Chi-square test, t-student Test and Logistic Regression were used to analyze the relationship between ABO blood groups and oral cancer. The frequency of blood group B was significantly higher in oral cancer patients than controls (32% vs 13%) (p value=0.01), but Rh factor did not show significant difference between cases and controls. According to Logistic Regression, people with blood group B and those older than 50 had 3.5 and 19.4 times elevated risk of developing oral cancer, respectively. The frequency of squamous cell cancer was also significantly higher in men and people older than 50. On the other hand, females, people under 50, and those with blood group B were at 5.6, 2.9 and 4.3 times higher risk of developing non-squamous cell oral cancer,respectively. People with blood group B are at a greater risk of developing oral cancer, and female patients under 50 years of age with blood group B have the highest risk to develop non-squamous cell oral cancer.

Mechanical Properties of Aluminium Metal Matrix Nanocomposites Manufactured by Assisted-Flake Powder Thixoforming Process

Saud M. Almotairy,A. Fadavi Boostani,M. Hassani,D. Wei,Z. Y. Jiang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5

This study discusses the superior effect of thixoforming process on enhancing the tensile properties of aluminium matrixcomposite produced using flake metallurgy route. The flake metallurgy process was utilised to manufacture aluminiummatrix composites followed by thixoforming process. Microstructural investigations carried out using transmission electronmicroscope have shown the synergic effect of thixoforming process on rendering uniform distribution of SiC nanoparticlesassociated with lower porosity content. X-ray diffraction characterisations have revealed the promising effect of uniformdispersion of SiC nanoparticles on restricting the grain growth of aluminium matrix within nanoscale regime (90 nm) evenat high semi-solid thixoforming temperatures (575 °C). The achieved results of tensile tests have shown a profound effect offlake metallurgy of aluminium powder through dual speed ball milling. These results are higher than those achieved by lowspeed and high speed even with higher SiC content. This was attributed to the uniform confinement of SiC nanoparticleswithin the samples produced using flake-assisted forming process compared to the ones manufactured using ball millingassistedprocesses.

New method for generation of artificial ground motion by a nonstationary Kanai-Tajimi model and wavelet transform

Amiri, G. Ghodrati,Bagheri, A.,Fadavi, M. Techno-Press 2007 Structural Engineering and Mechanics, An Int'l Jou Vol.26 No.6

Considering the vast usage of time-history dynamic analyses to calculate structural responses and lack of sufficient and suitable earthquake records, generation of artificial accelerograms is very necessary. The main target of this paper is to present a novel method based on nonstationary Kanai-Tajimi model and wavelet transform to generate more artificial earthquake records, which are compatible with target spectrum. In this regard, the generalized nonstationary Kanai-Tajimi model to include the nonstationary evaluation of amplitude and dominant frequency of ground motion and properties of wavelet transform is used to generate ground acceleration time history. Application of the method for El Centro 1940 earthquake and two Iranian earthquakes (Tabas 1978 and Manjil 1990) is presented. It is shown that the model and identification algorithms are able to accurately capture the nonstationary features of these earthquake accelerograms. The statistical characteristics of the spectral response of the generated accelerograms are compared with those for the actual records to demonstrate the effectiveness of the method. Also, for comparison of the presented method with other methods, the response spectra of the synthetic accelerograms compared with the models of Fan and Ahmadi (1990) and Rofooei et al. (2001) and it is shown that the response spectra of the synthetic accelerograms with the method of this paper are close to those of actual earthquakes.

Ultrasonic Atomizer for Aeroponic Cultivation: Effect of Nutrient Solution Dosage, Voltage, and Horn Dimensions

Mirzabe Amir Hossein,Hajiahmad Ali,Fadavi Ali,Rafiee Shahin 한국농업기계학회 2022 바이오시스템공학 Vol.47 No.2

Purpose Due to the advantages of aeroponic compared to other cultivation systems, the advantages of piezoelectric ultrasonic compared to other mist makers, and lack of research done to study the parameters affecting the misting rate of nutrient solutions with the approach used in aeroponic systems, the current work was carried out. Methods The effects of dosage of nutrient solution, voltage, horn diameter, and horn height on the misting rate, circuit current, power consumption, amplitude of sound waves, Δ pH, Δ EC (electrical conductivity), and Δ TDS (total dissolved solids) were investigated. Physical properties of the solution (density, viscosity, surface tension, and speed of sound) were measured. Moreover, optimization was performed to determine suitable ranges of independent variables. Results Obtained results showed that the four mentioned independent variables significantly affect the six dependent variables (P<1%). The misting rate was in the range of 96 to 411.6 g h−1. At the temperature of 25 °C and for different concentrations of fertilizer, the density, surface tension, viscosity, speed of sound in the solution, initial TDS, and initial pH varied between 1002.3– 1004.8 kg m−3, 73.33–74.42 mN m−1, 1.009–1.395 mPa s, 1489–1502 m s−1, 1323–8865 mg L−1, and 6.18–6.84, respectively. Also, theoretically calculated mist mean droplet diameter was in the range of 2.868 to 2.880 μm for different fertilizer doses. Conclusion Mist generation by piezoelectric ceramics is an efficient method for use in aeroponic systems. Although the obtained misting rates in this study differ from the industrial values, the use of several piezoelectric ceramics is the simplest solution to this problem.

Combination of Exercise and Acupuncture Versus Acupuncture Alone for Treatment of Myofascial Pain Syndrome: A Randomized Clinical Trial

Bina Eftekharsadat,Elmira Porjafar,Fariba Eslamian,Seyed Kazem Shakouri,Hamid Reza Fadavi,Seyed Ahmad Raeissadat,Arash Babaei-Ghazani 사단법인약침학회 2018 Journal of Acupuncture & Meridian Studies Vol.11 No.5

Myofascial pain syndrome (MPS) is a common musculoskeletal disorder. This study was designed to compare the effects of aerobic exercise plus acupuncture with acupuncture alone in treatment of patients with MPS. Sixty-four patients (55 female and 9 male) with MPS in their neck and shoulders participated in the study with mean age of 33.1 ± 6.4 years. Participants were randomly allocated to aerobic exercise plus acupuncture (n = 32) or acupuncture alone (n = 32) groups. Outcome measurements included visual analog scale, pressure pain threshold, neck disability index, and quality of life that was measured with QoL-SF36 scale. Each group received 10 sessions of acupuncture in combination with aerobic exercise or acupuncture alone. The outcome measures were evaluated at baseline, at the end of the last treatment session, and at 1-month follow-up visit. While participants were waiting for their 1-month follow-up visit, the patients who received combination therapy were asked to continue their aerobic exercise by jogging 40 minutes a day. Although mean visual analog scale, pressure pain threshold, neck disability index, and QoL-SF36 were significantly improved in both groups (p < 0.001), there was no statistically significant difference among the measures between the two groups throughout the evaluated sessions. The interaction effect of time and groups did not show any significant difference among the outcome measures (p > 0.29).