Seismic Behavior of Frames with Bolted End Plate Connections Rehabilitated by Welded Haunches Under Near- and Far-Fault Earthquakes

Hamid Saberi,Vahid Saberi,Ali Kheyroddin,Mohsen Gerami 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.2

A retrofi t method for bolted end plate connections is the use of haunches. This method needs no change or replacement of connection components. The optimum selection of rehabilitation parameters like thickness or haunch-beam angle is of great importance for designers. Besides, one of the important factors for designers to select this retrofi t method, is the effi ciency of retrofi tting by haunches and the eff ectiveness of retrofi t parameters on behavior of retrofi tted frames in near- and far-fi eld earthquakes. The results of 2D numerical modeling of the frames shows that rehabilitation of the weak end plate connections using haunch improves the seismic behavior of the weak frame relative to the reference frame with connections designed according to AISC code. For example, the roof displacements are reduced by 8% averagely and the maximum story drifts in near and far-fi eld earthquakes are reduced by 22% and 12% in the rehabilitated frames compared to those of the reference frame. The results of 3D substructure numerical models, after verifi cation by experimental results, showed that the increase of haunch thickness from 12 to 18 mm did not signifi cantly increase the moment capacity and initial rotational stiff ness. However, the pinching in moment-rotation hysteresis is decreased. The increase of haunch angle from 30 to 60 resulted in shift of plastic hinge to haunch internal area and 100% reduction of energy absorption and initial rotational stiff ness compared to those of the reference specimen. Since the change of retrofi t method parameters results in change of stiff ness and natural time period of the structure and the aff ecting parameter on structure dynamic behavior is “the ratio between structure main time frequency to earthquake predominant time period”, the selection of the fi rst haunch thickness with an angle of 30 degree toward the beam that satisfy the requirements of FEMA350 will be economic and optimized.

Gene Expression Biodosimetry: Quantitative Assessment of Radiation Dose with Total Body Exposure of Rats

Saberi, Alihossein,Khodamoradi, Ehsan,Birgani, Mohammad Javad Tahmasebi,Makvandi, Manoochehr Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.18

Background: Accurate dose assessment and correct identification of irradiated from non-irradiated people are goals of biological dosimetry in radiation accidents. Objectives: Changes in the FDXR and the RAD51 gene expression (GE) levels were here analyzed in response to total body exposure (TBE) to a 6 MV x-ray beam in rats. We determined the accuracy for absolute quantification of GE to predict the dose at 24 hours. Materials and Methods: For this in vivo experimental study, using simple randomized sampling, peripheral blood samples were collected from a total of 20 Wistar rats at 24 hours following exposure of total body to 6 MV X-ray beam energy with doses (0.2, 0.5, 2 and 4 Gy) for TBE in Linac Varian 2100C/D (Varian, USA) in Golestan Hospital, in Ahvaz, Iran. Also, 9 rats was irradiated with a 6MV X-ray beam at doses of 1, 2, 3 Gy in 6MV energy as a validation group. A sham group was also included. After RNA extraction and DNA synthesis, GE changes were measured by the QRT-PCR technique and an absolute quantification strategy by taqman methodology in peripheral blood from rats. ROC analysis was used to distinguish irradiated from non-irradiated samples (qualitative dose assessment) at a dose of 2 Gy. Results: The best fits for mean of responses were polynomial equations with a R2 of 0.98 and 0.90 (for FDXR and RAD51 dose response curves, respectively). Dose response of the FDXR gene produced a better mean dose estimation of irradiated "validation" samples compared to the RAD51 gene at doses of 1, 2 and 3 Gy. FDXR gene expression separated the irradiated rats from controls with a sensitivity, specificity and accuracy of 87.5%, 83.5% and 81.3%, respectively, 24 hours after dose of 2 Gy. These values were significantly (p<0.05) higher than the 75%, 75% and 75%, respectively, obtained using gene expression of RAD51 analysis at a dose of 2 Gy. Conclusions: Collectively, these data suggest that absolute quantification by gel purified quantitative RT-PCR can be used to measure the mRNA copies for GE biodosimetry studies at comparable accuracy to similar methods. In the case of TBE with 6MV energy, FDXR gene expression analysis is more precise than that with RAD51 for quantitative and qualitative dose assessment.

Effect of slice inclination and object position within the field of view on the measurement accuracy of potential implant sites on cone-beam computed tomography

Saberi, Bardia Vadiati,Khosravifard, Negar,Nourzadeh, Alireza Korean Academy of Oral and Maxillofacial Radiology 2020 Imaging Science in Dentistry Vol.50 No.1

Purpose: The purpose of this study was to evaluate the accuracy of linear measurements in the horizontal and vertical dimensions based on object position and slice inclination in cone-beam computed tomography (CBCT) images. Materials and Methods: Ten dry sheep hemi-mandibles, each with 4 sites (incisor, canine, premolar, and molar), were evaluated when either centrally or peripherally positioned within the field of view (FOV) with the image slices subjected to either oblique or orthogonal inclinations. Four types of images were created of each region: central/cross-sectional, central/coronal, peripheral/cross-sectional, and peripheral/coronal. The horizontal and vertical dimensions were measured for each region of each image type. Direct measurements of each region were obtained using a digital caliper in both horizontal and vertical dimensions. CBCT and direct measurements were compared using the Bland-Altman plot method. P values <0.05 were considered to indicate statistical significance. Results: The buccolingual dimension of the incisor and premolar areas and the height of the incisor, canine, and molar areas showed statistically significant differences on the peripheral/coronal images compared to the direct measurements (P<0.05). Molar area height in the central/coronal slices also differed significantly from the direct measurements (P<0.05). Cross-sectional images of either the central or peripheral position had no marked difference from the gold-standard values, indicating sufficient accuracy. Conclusion: Peripheral object positioning within the FOV in combination with applying an orthogonal inclination to the slices resulted in significant inaccuracies in the horizontal and vertical measurements. The most undesirable effect was observed in the molar area and the vertical dimension.

Detection of peri-implant bone defects using cone-beam computed tomography and digital periapical radiography with parallel and oblique projection

Saberi, Bardia Vadiati,Khosravifard, Negar,Ghandari, Farnaz,Hadinezhad, Arash Korean Academy of Oral and Maxillofacial Radiology 2019 Imaging Science in Dentistry Vol.49 No.4

Purpose: To compare the diagnostic accuracy of cone-beam computed tomography (CBCT) with that of parallel(PPA) and oblique projected periapical(OPA) radiography for the detection of different types of peri-implant bone defects. Materials and Methods: Forty implants inserted into bovine rib blocks were used. Thirty had standardized bone defects(10 each of angular, fenestration, and dehiscence defects), and 10 were defect-free controls. CBCT, PPA, and OPA images of the samples were acquired. The images were evaluated twice by each of 2 blinded observers regarding the presence or absence and the type of the defects. The area under the receiver operating characteristic curve (AUC), sensitivity, and specificity were determined for each radiographic technique. The 3 modalities were compared using the Fisher exact and chi-square tests, with P<0.05 considered as statistical significance. Results: High inter-examiner reliability was observed for the 3 techniques. Angular defects were detected with high sensitivity and specificity by all 3 modalities. CBCT and OPA showed similar AUC and sensitivity in the detection of fenestration defects. In the identification of dehiscence defects, CBCT showed the highest sensitivity, followed by OPA and PPA, respectively. CBCT and OPA had a significantly greater ability than PPA to detect fenestration and dehiscence defects(P<0.05). Conclusion: The application of OPA radiography in addition to routine PPA imaging as a radiographic follow-up method for dental implantation greatly enhances the visualization of fenestration and dehiscence defects. CBCT properly depicted all defect types studied, but it involves a relatively high dose of radiation and cost.

Chitosan-Polyacrylic Acid Hybrid Nanoparticles as Novel Tissue Adhesive: Synthesis and Characterization

Javad Saberi,Mojtaba Ansari,Bahman Ebrahimi Hoseinzadeh,Soheila Salahshour Kordestani,Seyed Morteza Naghib 한국섬유공학회 2018 Fibers and polymers Vol.19 No.12

Chitosan (Cs)-poly acrylic acid (PAA) complex nanoparticles well dispersed and stable in aqueous solution was prepared by free radical polymerization of acrylic acid monomers (AA) in the presence of chitosan (Cs). Different concentrations of Cs and AA was cross-linked to form scalable hybrid nanoparticles (HNP). The physicochemical characterization of nanopolymers was investigated using FTIR, dynamic light scattering (DLS) and scanning electron microscopy (SEM). Infrared spectroscopy and electronic microscopy analysis results showed the preparation of Cs-PAA hybrid nanoparticles due to the formation of polyelectrolyte complexes and their spherical shape, respectively. The average particle size obtained under 180 nm for all samples obtained by using DLS analysis. A dhesion strength for the samples with a ratio of Cs/AA 1: 1 and 0.2: 1 was 50 to 120 kPa and 120 to 230 kPa , respectively. Cytotoxicity assay (MTT) showed that cell activity for concentrations X/5 and X/10 was over 7 5 %, demonstrating the sample extracts have suitable cytocompatibility. In addition, hemolytic assay of the samples represents below 0.5 % (according to the standard) in damage extend to red blood cells. Furthermore, prepared tissue adhesive based on Cs-PAA hybrid NPs in terms of adhesion strength was competitive with commercial samples as well as satisfactory results in terms of biocompatibility and blood compatibility were achieved in comparison with commercial available adhesives based on cyanoacrylate.

Disorders of Gastrointestinal Motility & Sensation : Subjective Lactose Intolerance In Apparently Healthy Adults In Southern Iran: Is It Related To IBS?

( Mehdi Saberi Firouzi ),( Famaz Khademolhosseini ),( Davood Mehrabani ),( Maryam Yousefi ),( Moosa Salehi ),( Seyyed Taghi Heidary ) 대한소화기학회 2007 SIDDS Vol.9 No.-

Background/Alms: Lactase deficiency leads to maldigestion and malabsorption of lactose. The symptoms of this deficiency in some individuals are abdominal pain and distension, flatulence, and the passage of loose watery stools. This study aimed to investigate the prevalence of subjective lactose intolerance and its relation to Irritable Bowel Syndrome (IBS), demographic factors and living habits. Methods: A survey of 1978 individuals aged above 35 years was conducted in Shiraz, Southern Iran, using a questionnaire that consisted of items regarding demographic data, life style and gastrointestinal symptoms including those experienced after consumption of dairy products. Diagnosis of IBS was made on the basis of Rome II criteria. Results: A total of 562 subjects reported lactose intolerance (28.41%). The prevalence was significantly higher in females, in subjects taking NSAIDs or acetaminophen, and in patients with irritable bowel syndrome. Subjective lactose intolerance was also associated with health-seeking behavior such as restricting diet, using herbal medicine, taking over-the-counter drugs and visiting a physician. On the other hand, no relation was found between lactose intolerance and age, smoking or the number of meals per day. Conclusions: Lactose intolerance has a relatively high prevalence in our region and is associated with irritable bowel syndrome. A test for lactose malabsorption should, therefore, be included in the work-up of patients with this syndrome.

Study of buckling stability of cracked plates under uniaxial compression using singular FEM

Sina Saberi,Parham Memarzadeh,Tadeh Zirakian 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.4

Buckling is one of the major causes of failure in thin-walled plate members and the presence of cracks with different lengths and locations in such structures may adversely affect this phenomenon. This study focuses on the buckling stability assessment of centrally and non-centrally cracked plates with small-, intermediate-, and large-size cracks, and different aspect ratios as well as support conditions, subjected to uniaxial compression. To this end, numerical models of the cracked plates were created through singular finite element method using a computational code developed in MATLAB. Eigen-buckling analyses were also performed to study the stability behavior of the plates. The numerical results and findings of this research demonstrate the effectiveness of the crack length and location on the buckling capacity of thin plates; however, the degree of efficacy of these parameters in plates with various aspect ratios and support conditions is found to be significantly different. Overall, careful consideration of the aspect ratio, support conditions, and crack parameters in buckling analysis of plates is crucial for efficient stability design and successful application of such thin-walled members.

Comparison of Bolted End plate and T-Stub Connections Sensitivity to Bolt Diameter on Cyclic Behavior

Hamid Saberi,Ali Kheyroddin,Mohsen Gerami 한국강구조학회 2014 International Journal of Steel Structures Vol.14 No.3

Considering the construction limitations, proper and correct design of connections is vital and of great importance. At theconstruction stage, it is probable to use a connection bolt with a diameter less than the design assumptions. It can occur dueto an imperfection in construction or even to changes in the function of the building. The unforeseen changes can increase thestructural load, and consequently the moment and shear force demand values. Therefore, the present paper is aimed to examinethe sensitivity of the bolted connections to the diameter of bolts using a numerical method. The results show that bolted T-stubconnections are more sensitive to bolt diameter than end plate connections. Hence, the bolted end plate connections arerecommended where the imperfection in construction or changes in function of the building is probable. Moreover, inconstruction of bolted connections, if changing the number of bolts regarding the constant total cross sectional area isconsidered, it is recommended to use the symmetric arrangement of bolts on each beam flange. In design of connections fora particular frame according to AISC, the moment capacity of T-stub connection is higher than that of end plate connection. However, the total energy absorptions of these connection types are approximately equal.

Computationally efficient direct predictive speed control of PMSMs fed by three‑level NPC convertors with guaranteed stability

Sajad Saberi,Behrooz Rezaie 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.7

Direct predictive speed control (DPSC) using a finite control set MPC (FCS-MPC) is a popular control method for multi-level converters. In FCS-MPC-based designs, there are two key issues. First, when the number of switching states increases, the computational burden dramatically increases, which makes real-time implementation impractical when compared to traditional modulation methods such as field-oriented control (FOC). The issue of stability is another key concern with DPSC. In the present study, the speed of a permanent magnet synchronous motor (PMSM) fed by a three-level neutral-point clamped (3L-NPC) convertor is controlled using a computationally efficient DPSC technique with hexagon candidate region (HCR). Back-stepping is also used in the proposed method to generate the q-axis current reference and continuous d–q axis control voltage for the DPSC to guarantee the stability of the closed loop system using the Lyapunov stability theorem. Furthermore, in HCR, the continuous control law checks the voltage vectors while only passing the vectors that do not jeopardize the stability of the system. As a result, stability is taken into account and also the number of voltage candidates for FCS-MPC decreases significantly. This in turn leads to reductions in the computational burden. The system is simulated in MATLAB/Simulink to validate the efficiency of the proposed method.

Application of artificial intelligence to magnetite-based magnetorheological fluids

Hossein Saberi,Ehsan Esmaeilnezhad,최형진 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.100 No.-

Magnetorheological (MR)fluids are intelligentfluids that change their state under a magneticfield andcan be extensively applied in several industries. In this study, a model was presented to predict the MRbehavioral trend of magnetite-based MRfluids using deep neural networks. The MR data of nine sampleswith several magnetite nanoparticle concentrations and different silicone oil viscosities were used fornetwork construction and testing; the aforementioned data were obtained under several magneticfieldstrengths. Seven samples were used for network training/testing within the training interval and twosamples were applied for evaluating the network accuracy outside the network training interval. Severalnetworks, such as the multi-layer perceptron (MLP), radial basis function, and adaptive neuro-fuzzyinference system, were employed, and the results were analyzed. The accuracy parameters (R2 and RMSE)of the MLP network for the training data (0.99625 and 0.00867) and test data (0.99130 and 0.01621), aswell as a comparison between the predicted and laboratory-measured results of the two samples thathad not been used in the modeling step, demonstrated the exceptional performance of the proposedmethod and an equation that was derived for predicting the shear stress. The latter equation enablesresearchers to achieve their needs without performing time-and cost-consuming MR tests in thelaboratory.