Investigating the effect of bond slip on the seismic response of RC structures

Fallah, Mohammad Mehdi,Shooshtari, Ahmad,Ronagh, Hamid Reza Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.46 No.5

It is reasonable to assume that reinforced concrete (RC) structures enter the nonlinear range of response during a severe ground motion. Numerical analysis to predict the behaviour therefore must allow for the presence of nonlinear deformations if an accurate estimate of seismic response is aimed. Among the factors contributing to inelastic deformations, the influence of the degradation of the bond slip phenomenon is important. Any rebar slip generates an additional rotation at the end regions of structural members which are not accounted for in a conventional analysis. Although these deformations could affect the seismic response of RC structures considerably, they are often neglected due to the unavailability of suitable models. In this paper, the seismic response of two types of RC structures, designed according to the Iranian concrete code (ABA) and the Iranian seismic code (2800), are evaluated using nonlinear dynamic and static analyses. The investigation is performed using nonlinear dynamic and static pushover analysis considering the deformations due to anchorage slip. The nonlinear analysis results confirm that bond slip significantly influences the seismic behavior of RC structure leading to an increase of lateral deformations by up to 30% depending on the height of building. The outcomes also identify important parameters affecting the extent of this influence.

An inverse approach for the calculation of flexibility coefficient of open-side cracks in beam type structures

Fallah, N.,Mousavi, M. Techno-Press 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.2

An inverse approach is presented for calculating the flexibility coefficient of open-side cracks in the cross sectional of beams. The cracked cross section is treated as a massless rotational spring which connects two segments of the beam. Based on the Euler-Bernoulli beam theory, the differential equation governing the forced vibration of each segment of the beam is written. By using a mathematical manipulation the time dependent differential equations are transformed into the static substitutes. The crack characteristics are then introduced to the solution of the differential equations via the boundary conditions. By having the time history of transverse response of an arbitrary location along the beam, the flexibility coefficient of crack is calculated. The method is applied for some cracked beams with solid rectangular cross sections and the results obtained are compared with the available data in literature. The comparison indicates that the predictions of the proposed method are in good agreement with the reported data. The procedure is quite general so as to it can be applicable for both single-side crack and double-side crack analogously. Hence, it is also applied for some test beams with double-side cracks.

Incidence and Survival in Breast Cancer Patients and Stressful Life Events

Fallah, Raheleh,Akbari, Mohammad Esmaeil,Azargashb, Eznollah,Khayamzadeh, E Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.no.sup3

Due to increasing incidence of breast cancer, recognition of risk factors has become increasingly important. Over the past few decades, among risk factors of this disease, stressful life events have attracted particular attention, but their relationship with breast cancer incidence and survival remains a mystery. This study aimed to examine the relationship between severe stressful life events and incidence and survival of women with breast cancer. In this case-control study, using a structured telephone interview with 355 women with breast cancer and also with 516 women with benign breast diseases who were matched in demographic characteristics, necessary information about the experience of major stressful events in the years before the diagnosis were collected. Data were analyzed using statistical methods of ${\chi}^2$, t, and Kaplan-Meier with a significance level of <0.05. Generally, in the case and control groups, there were no significant association between experience of stressful life events and incidence of breast cancer. Regarding associations between each of the events and incidence of breast cancer only "severe interpersonal problems with spouse" was significant. In the breast cancer group, even after controlling confounding variables, there was no significant association between major stressful events and disease-free survival, or overall 5-and 10-year survival. In this study, only "severe interpersonal problems with spouse" was confirmed as a risk factor. This result can be useful in developing preventive policies. More research regarding the interactive effects of psycho-social factors in the incidence and survival of breast cancer with stressful life events is recommended.

Damage identification in laminated composite plates using a new multi-step approach

Narges Fallah,Seyed Rohollah Hoseini Vaez,Hossein Fasihi 국제구조공학회 2018 Steel and Composite Structures, An International J Vol.29 No.1

In this paper a new multi-step damage detection approach is provided. In the first step, condensed modal residual vector based indicator (CMRVBI) has been proposed to locate the suspected damaged elements of structures that have rotational degrees of freedom (DOFs). The CMRVBI is a new indicator that uses only translational DOFs of the structures to localize damaged elements. In the next step, salp swarm algorithm is applied to quantify damage severity of the suspected damaged elements. In order to assess the performance of the proposed approach, a numerical example including a three-layer square laminated composite plate is studied. The numerical results demonstrated that the proposed CMRVBI is effective for locating damage, regardless of the effect of noise. The efficiency of proposed approach is also compared during both steps. The results demonstrate that in noisy condition, the damage identification approach is capable for the studied structure.

Total Shielding Efficiency, Reflection Loss and Absorption Loss of Nanoparticles/Paraffin Wax Absorber in the Shielding of Electromagnetic Pollution

Rohollah Fallah Madvari,Sedigheh Hosseinabadi,Hamideh Bidel,Gholamhossein Pourtaghi,Fereydoon Laal 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.6

The extensive development of diverse electronic/electrical systems has led to increased exposure to electromagnetic field and can result in many adverse effects on humans, other living beings, safety operation of various equipment, etc. Electromagnetic interference (EMI) shielding materials are in greater demand to suppress this electromagnetic pollution. The present study investigates the factors affecting the shielding effi ciency of carbon black-based nanocomposite shields. Fe3O4/carbon black nanocomposite (CBN) with paraffi n wax were fabricated by melt mixing methods in different weight percentages of the dispersants. The EMI shielding properties of the nanocomposites were measured using a vector network analyzer in the frequency range of 8.2 to 12.5 GHz (X band) based on the transfer/reflection method. The total shielding efficiency was used to assess the shield's protection performance. Based on the weight percentages of nanocomposite constituents, four samples were obtained. The highest average of total shielding effi ciency in equal thickness belonged to the sample with 50% CBN and 15% Fe3O4 nanoparticles in weight. At different thicknesses, the highest average total shielding efficiency was related to the minimum thickness of 0.8 mm. Also, in with increasing the frequency decreased the mean total shielding efficiency in the samples. Depending on the type and weight percentage of nanocomposite compounds, one of the absorption or reflection mechanisms can be the main mechanism in reducing or eliminating electromagnetic waves in nanocomposite shields. The shield thickness and frequency of electromagnetic waves aff ect the protective performance of the shield.

An inverse approach for the calculation of flexibility coefficient of open-side cracks in beam type structures

N. Fallah,M. Mousavi 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.41 No.2

An inverse approach is presented for calculating the flexibility coefficient of open-side cracks in the cross sectional of beams. The cracked cross section is treated as a massless rotational spring which connects two segments of the beam. Based on the Euler-Bernoulli beam theory, the differential equation governing the forced vibration of each segment of the beam is written. By using a mathematical manipulation the time dependent differential equations are transformed into the static substitutes. The crack characteristics are then introduced to the solution of the differential equations via the boundary conditions. By having the time history of transverse response of an arbitrary location along the beam, the flexibility coefficient of crack is calculated. The method is applied for some cracked beams with solid rectangular cross sections and the results obtained are compared with the available data in literature. The comparison indicates that the predictions of the proposed method are in good agreement with the reported data. The procedure is quite general so as to it can be applicable for both single-side crack and doubleside crack analogously. Hence, it is also applied for some test beams with double-side cracks.

Effect of Microwave Irradiation on Morphology and Size of Anatase Nano Powder: Efficient Photodegradation of 4-Nitrophenol by W-doped Titania

Abdollah Fallah Shojaei,Mohammad Hassan Loghmani 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.12

Anatase nanocrystalline and its tungsten-doped (0.4, 2, and 4 mol %) powders have been synthesized by microwave irradiation through hydrolysis of titanium tetra-isopropoxide (TIP) in aqueous solution. The materials are characterized by XRD, Raman, SEM-EDX, TEM, FT-IR and UV-vis techniques. The nanocrystalline TiO2 particles are 30 nm in nature and doping of tungsten ion decreases their size. As seen in TEM images, the crystallites of W (4 mol %) doped TiO2 are small with a size of about 10 nm. The photocatalytic activity was tested on the degradation of 4-nitrophenol (4-NP). Catalytic activities of W-doped and pure TiO2 were also compared. The results show that the photocatalytic activity of the W-doped TiO2 photocatalyst is much higher than that of pure TiO2. Degradation decreases from 96 to 50%, during 115 min, when the initial 4-NP concentration increases from 10 to120 ppm. Maximum degradation was obtained at 35 mg of photocatalyst.

Failure analysis of a heat-resistant stainless steel ring in a gas turbine burner

Aliakbar Fallah Sheykhlari,Saeed Khani Moghanaki,Meisam Khodabakhshi 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.4

Hot gas path components in gas turbines are damaged by several mechanisms due to aggressive environments. In this research, the cracking of an insert ring, which is composed of Nb-stabilized heat-resistant stainless steel, after 8000 operation hours, is investigated. The microstructure of the ring is examined by optical and scanning electron microscopes equipped with energy-dispersive X-ray spectroscopy. The generated stress and strain within the ring during a complete operation cycle (startup to shutdown) of gas turbine are simulated by finite element simulation software. The microstructural investigations indicate the formation of some precipitates that mainly contain nitrogen atoms. The development of tensile loads within the ring during shutdown and brittle N-contained precipitates leads to cracking. The indicators of both types of hot corrosion are also observed.

Systematic Review of Data Mining Applications in Patient-Centered Mobile-Based Information Systems

Mina Fallah,Sharareh R. Niakan Kalhori 대한의료정보학회 2017 Healthcare Informatics Research Vol.23 No.4

Objectives: Smartphones represent a promising technology for patient-centered healthcare. It is claimed that data mining techniques have improved mobile apps to address patients’ needs at subgroup and individual levels. This study reviewed the current literature regarding data mining applications in patient-centered mobile-based information systems. Methods: We systematically searched PubMed, Scopus, and Web of Science for original studies reported from 2014 to 2016. After screening 226 records at the title/abstract level, the full texts of 92 relevant papers were retrieved and checked against inclusion criteria. Finally, 30 papers were included in this study and reviewed. Results: Data mining techniques have been reported in development of mobile health apps for three main purposes: data analysis for follow-up and monitoring, early diagnosis and detection for screening purpose, classification/prediction of outcomes, and risk calculation (n = 27); data collection (n = 3); and provision of recommendations (n = 2). The most accurate and frequently applied data mining method was support vector machine; however, decision tree has shown superior performance to enhance mobile apps applied for patients’ self-management. Conclusions: Embedded data-mining-based feature in mobile apps, such as case detection, prediction/classification, risk estimation, or collection of patient data, particularly during self-management, would save, apply, and analyze patient data during and after care. More intelligent methods, such as artificial neural networks, fuzzy logic, and genetic algorithms, and even the hybrid methods may result in more patients-centered recommendations, providing education, guidance, alerts, and awareness of personalized output.

High Selective Oxidation of Alcohols Based on Trivalent Ion (Cr3+ and Co3+) Complexes Anchored on MCM-41 as Heterogeneous Catalysts

Abdollah Fallah Shojaei,Mahboubeh Delavar Rafie,Mohammad Hassan Loghmani 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.8

Cr(III) and Co(III) complexes with acetylacetonate were anchored onto a mesoporous MCM-41 through Schiff condensation. The materials were characterized by XRD, FT-IR, BET, CHN and ICP techniques. Elemental analysis of samples revealed that one C=N bond was formed through Schiff condensation on MCM-41 surface. The catalysts were tested for the alcohol oxidations using t-butyl hydroperoxide (TBHP) and H2O2 as oxidant. The catalytic experiments were carried out at both room temperature and reflux condition. Various solvents such as dichloromethane, acetonitrile and water were examined in the oxidation of alcohols. Among the different solvents, catalytic activity is found more in acetonitrile. Further, the catalysts were recycled three times in the oxidation of alcohols and no major change in the conversion and selectivity is observed, which shows that the immobilized metal- acetylacetonate complexes are stable under the present reaction conditions.