Effect of Activated Pozzolan with Ca(OH) 2 and nano-SiO2 on Microstructure and Hydration of High-Volume Natural Pozzolan Paste

The main aim of this study is to investigate the effect of activated pozzolan on hydration and microstructure of high-volume natural pozzolan paste. Thermal activation of natural pozzolan with Ca(OH)2 has been applied with nano-silica (NS) as activator at three different temperatures. X-ray diffraction (XRD), thermogravimetric analysis (TGA), laser particle analysis, scanning electron microscopy (SEM) with energy dispersive spectroscopy were employed. In order to analyze the test results, notions of “pre C-S-H” based on XRD and TGA results of activated pozzolan powders has been used. SEM images indicated microstructural improvements of the pastes with activated pozzolans compared to paste with natural pozzolan and natural pozzolan incorporating NS, showing the pore-filling effect of activated pozzolans. The microstructural improvements were proportion to the amount of pre C-S-H formed during the activation of pozzolan

The Best Location of Belt Truss System in Tall Buildings Using Multiple Criteria Subjected to Blast Loading

The main goal of this paper is to investigate the effect of blast phenomenon on structures to determine the best location of belt truss system in tall buildings. For this purpose, one of the exterior frames of a tall steel building, in which the belt truss is located, is considered. The steel frame model is subjected to two different charges of equivalent weight which are applied in two different standoff distances. In this research, the best location of the belt truss system is determined using OpenSees software based on the nonlinear dynamic analysis. The best location of the belt truss system for different types of loading is investigated both with and without considering the post-buckling effect for all members of the belt truss system. The results show that when blast charges are located in a 5-meter range from the building (R=5), post buckling effect of truss elements are more obvious than the case in which blast charges are located in a 10-meter range (R=10); this, in turn, causes the amount of base moment to be completely different when the belt truss is located in the first storey in comparison to the cases where the belt truss is located in any other stories. In addition, if the explosion occurs near the building when the base moment is considered as a criterion, the post buckling effect has a significant role

Finite Element Analysis of Functionally Graded Beams using Different Beam Theories

The present study deals with buckling, free vibration, and bending analysis of Functionally Graded (FG) and porous FG beams based on various beam theories. Equation of motion and boundary conditions are derived from Hamilton’s principle, and the finite element method is adopted to solve problems numerically. The FG beams are graded through the thickness direction, and the material distribution is controlled by power-law volume fraction. The effects of the different values of the power-law index, porosity exponent, and different boundary conditions on bending, natural frequencies and buckling characteristics are also studied. A new function is introduced to approximate the transverse shear strain in higher-order shear deformation theory. Furthermore, shifting the position of the neutral axis is taken into account. The results obtained numerically are validated with results obtained from ANSYS and those available in the previous work. The results of this study specify the crucial role of slenderness ratio, material distribution, and porosity condition on the characteristic of FG beams. The deflection results obtained by the proposed function have a maximum of six percent difference when the results are compared with ANSYS. It also has better results in comparison with the Reddy formulae, especially when the beam becomes slender. Doi: 10.28991/cej-2020-03091604 Full Text: PD

Optimal Location of Energy Dissipation Outrigger in High-rise Building Considering Nonlinear Soil-structure Interaction Effects

Buckling-restrained braces (BRBs) emerged to improve the seismic performance of high-rise structures as compared to the ordinary diagonal bracing. In this paper, the seismic performance of braced buildings with the BRB outrigger system is investigated to determine the optimal configuration of BRB outrigger, considering the nonlinear SSI effect. For this purpose, the nonlinear dynamic analysis is carried out on four braced buildings with a BRB outrigger system placed on three different soil types. The outrigger configuration changes from first to the top story to capture the seismic performance of different locations of BRB outrigger. It is observed that the outrigger location affects the seismic performance, which is measured in terms of inter-story drift ratio, story displacement, story shear, and energy dissipation capacity. The results are compared to the fixed base condition buildings, which proves considering SSI, shifts the optimal location to the upper story of the structure. Moreover, the effect of soil’s stiffness on the seismic responses of structures and the optimal BRB outrigger location is investigated. Finally, the merits of BRB outrigger are shown by comparing its seismic performance that of the conventional outrigger, under frequent, basic, and rare earthquakes. The results show that the optimal locations of different 2-D buildings rested on the dense soil, medium soil, and soft clay are obtained at 0.6, 0.65, and 0.7 of the building’s height (H), respectively. Also, the results show that the optimum location of the BRB outrigger system based on the energy dissipation criteria is 0.45H to 0.65H

An Artificial Neural Network For Hedging Crude Oil

A neural network model for hedging crude oil is introduced.  The NYMEX futures prices is used to investigate the effectiveness of this model. Empirical results show that the neural network model reduces price risk more than other approaches

Effects of Shape Memory Alloys on Response of Steel Structural Buildings within Near Field Earthquakes Zone

Base isolation is one of the effective ways for controlling civil engineering structures in seismic zone which can reduce seismic demand. Also is an efficient passive control mechanism that protects its superstructure during an earthquake. However, residual displacement of base-isolation systems, resulting from strong ground motions, remain as the main obstacle in such system’s serviceability after the earthquake. Shape Memory Alloys (SMA) is amongst the newly introduced smart materials that can undergo large nonlinear deformations with considerable dissipation of energy without having any permanent displacement afterward. This property of SMA may be utilized for designing of base isolation system to increase the structure’s serviceability. Here, a proposed semi-active isolation system combines laminated rubber bearing system with shape memory alloy, to take advantage of SMAs high elastic strain range, in order to reduce residual displacements of the laminated rubber bearing. Merits of the system are demonstrated by comparing it to common laminated rubber bearing isolation systems. It is found that the optimal application of SMAs in base-isolation systems can significantly reduce bearings’ residual displacements. In this study, OpenSees program for a three dimensional six-storey steel frame building has been used by locating the isolators under the columns for investigating the feasibility of smart base isolation systems, i.e., the combination of traditional Laminated Rubber Bearing (LRB) with the SMA, in reducing the structure’s isolated-base response to near field earthquake records are examined. Also, a new configuration of SMAs in conjunction with LRB is considered which make the system easier to operate and maintain

Temperature measurement and control system for transtibial prostheses: single subject clinical evaluation.

The snug fit of a prosthetic socket over the residual limb can disturb thermal balance and put skin integrity in jeopardy by providing an unpleasant and infectious environment. The prototype of a temperature measurement and control (TM&C) system was previously introduced to resolve thermal problems related to prostheses. This study evaluates its clinical application in a setting with reversal, single subject design. The TM&C system was installed on a fabricated prosthetic socket of a man with unilateral transtibial amputation. Skin temperature of the residual limb without prosthesis at baseline and with prosthesis during rest and walking was evaluated. The thermal sense and thermal comfort of the participant were also evaluated. The results showed different skin temperature around the residual limb with a temperature decrease tendency from proximal to distal. The TM&C system decreased skin temperature rise after prosthesis wearing. The same situation occurred during walking, but the thermal power of the TM&C system was insufficient to overcome heat build-up in some regions of the residual limb. The participant reported no significant change of thermal sense and thermal comfort. Further investigations are warranted to examine thermography pattern of the residual limb, thermal sense, and thermal comfort in people with amputation.N/

Temperature measurement and control system for transtibial prostheses: functional evaluation.

The accumulation of heat inside the prosthetic socket increases skin temperature and fosters perspiration, which consequently leads to high tissue stress, friction blister, discomfort, unpleasant odor, and decreased prosthesis suspension and use. In the present study, the prototype of a temperature measurement and control (TM&C) system was designed, fabricated, and functionally evaluated in a phantom model of the transtibial prosthetic socket. The TM&C system was comprised of 12 thermistors divided equally into two groups that arranged internal and external to a prosthetic silicone liner. Its control system was programmed to select the required heating or cooling function of a thermal pump to provide thermal equilibrium based on the amount of temperature difference from a defined set temperature, or the amount of difference between the mean temperature recorded by inside and outside thermistors. A thin layer of aluminum was used for thermal conduction between the thermal pump and different sites around the silicone liner. The results showed functionality of the TM&C system for thermoregulation inside the prosthetic socket. However, enhancing the structure of this TM&C system, increasing its thermal power, and decreasing its weight and cost are main priorities before further development.The Hong Kong Polytechnic University supported all expenses of functional evaluation. Moreover, The ST&G Corporation, South Korea, has donated silicone liners for functional evaluation. The authors received no more support for conduction of this stud

An epidemiological survey of psychiatric disorders in Iran

BACKGROUND: The nation-wide epidemiological survey of psychiatric disorders in term of lifetime prevalence is not adequately known in Iran. The prevalence of lifetime psychiatric disorders was estimated among the population of aged 18 and over on gender, age group, educational level, occupational status, marital status, and residential area. METHODS: The subjects were 25,180 individuals selected through a clustered random sampling method. The psychiatric disorders were diagnosed on the bases of Diagnostic and Statistical Manual of Mental Disorders-IV criteria. It is the first study in which the structured psychiatric interview administered to a representative sample of the Iranian population age 18 and over by the 250 trained clinical psychologist interviewers. The data was entered through EPI-Info software twice in an attempt to prevent any errors and SPSS-11 statistical software was also used for analyses. The odds ratios and their confidence intervals estimated by using logistic regression. RESULTS AND DISCUSSION: The prevalence of psychiatric disorders was 10.81%. It was more common among females than males (14.34% vs. 7.34%, P < 0.001). The prevalence of anxiety and mood disorders were 8.35% and 4.29% respectively. The prevalence of psychotic disorders was 0.89%; neuro-cognitive disorders, 2.78% and dissociative disorders, 0.77%. Among mood disorders, major depressive disorder (2.98%) and among anxiety disorders, phobic disorder (2.05%) had the higher prevalence. The prevalence of psychiatric disorders among divorced and separated 22.31%; residents of urban areas 11.77%; illiterates 13.80%; householders 15.48%; unemployed 12.33% that were more than other groups. CONCLUSION: The mental health pattern in Iran is similar to the western countries, but it seems that the prevalence of psychiatric disorders in Iran may be lower than these countries. It is estimated that at least about 7 millions of Iranian population suffer from one or more of the psychiatric disorders. It shows the importance of the role of the psychiatric disorders in providing preventive and management programs in Iran

Prevalence of obsessive-compulsive disorder in Iran

BACKGROUND: Estimates of the annual prevalence for Obsessive Compulsive Disorder (OCD) were consistent across the international sites range, 1.9% – 2.5%. The nine population surveys, which used Diagnostic Interview Schedule, estimated a six-month prevalence of OCD ranging from 0.7% to 2.1%. This study performed in order to determine the prevalence of OCD in a population-based study among Iranian adults aged 18 and older and to study the association of them with factors such as sex, marital status, education, type of occupation and residential area. METHODS: A cross-sectional nationwide epidemiological study of the Iranian population aged 18 and older was designed to estimate the prevalence of psychiatric disorders and their association with the above mentioned factors. 25180 individuals were selected and interviewed through a randomized systematic and cluster sampling method from all Iranian households. Schedule for Affective Disorders and Schizophrenia (SADS) and Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV) criteria were used in diagnosis of OCD. 250 clinical psychologists interviewed the selected subjects face to face at their homes. RESULTS: The prevalence of OCD in Iran is 1.8% (0.7% and 2.8% in males and females; respectively). 50.3% of the survey sample were men, 49.9% women, 29.1% single, 67.45% married, 0.4% separated or divorced, 2.5% widow/widower and 4% undetermined. All of the above-mentioned factors were examined in the univariate and multivariate logistic regression models. Although the data did not fit the models well, but in univariate models, sex, the category "single" of marital status, age, the categories "business" and "housewife" and residential areas showed significant effect adjusting for the factors, but the models didn't fit the data properly. CONCLUSION: The study suggests that the prevalence of OCD is not rare in the community of Iran and is within the range of other countries. Similar to prior studies in other communities, OCD is more common in females than males