Modeling the effects of high strain rate loading on RC columns using Arbitrary Lagrangian Eulerian (ALE) technique

In recent years, many studies have been conducted by governmental and nongovernmental organizations across the world in an attempt to better understand the effect of explosive loads on buildings in order to better design against specific threats. This study is intended to contribute to increase the knowledge about how explosions affect reinforced concrete (RC) columns. In this study, a nonlinear model is developed to study the blast response of RC columns subjected to explosive loads. Numerical modeling of RC column under explosive load is presented using advanced finite element code LS DYNA. The obtained numerical model is validated with the experimental test and the results are in substantial agreement with the experimental data. ALE method for blast analysis is presented in the current research. The effects of scaled distance on the damage profile of RC columns are investigated. The results demonstrate that the level of damage increased with describing the scaled distance. Also the results shown duration for the blast loading, and hence the impulse, varies with charge masses at the specified scaled distance. Higher magnitude charge masses produced longer blast loading durations than lower magnitude charge masses. This means that at the same scaled distance, a charge mass of higher magnitude produced a higher impulse than the lower magnitude charge mass. The findings of this research represent the scaled distance is an important parameter that should be taken into account when analyzing the behavior of RC columns under explosive effects. The data collected from this research are being used to improve the knowledge of how structures will respond to a blast event, and improve finite element models for predicting the blast performance of concrete structures.Peer Reviewe

Association between vitamin d deficiencies in sarcoidosis with disease activity, course of disease and stages of lung involvements

Background: Despite negative association between 25-hydroxy vitamin D and incidence of many chronic respiratory diseases, this feature was not well studied in sarcoidosis. Current study investigated the association between 25-hydroxy vitamin D deficiency with sarcoidosis chronicity, disease activity, extra-pulmonary skin manifestations, urine calcium level and pulmonary function status in Iranian sarcoidosis patients. Results of this study along with future studies, will supply more effective programs for sarcoidosis treatment. Methods: Eighty sarcoidosis patients in two groups of insufficient serum level and sufficient serum level of 25-hydroxy vitamin D were studied. Course of sarcoidosis was defined as acute and chronic sarcoidosis. Pulmonary function test (PFT) was assessed by spirometry. Skin involvements were defined as biopsy proven skin sarcoidosis. 24-hour urine calcium level was used to specify the disease activity. Stages of lung involvements were obtained by CT-scan and chest X-ray. The statistical analyses were evaluated using Statistical Package for the Social Sciences. Results: A significant negative correlation was obtained between vitamin D deficiency in sarcoidosis patients and disease chronic course and stages two to four of lung involvements. Considering other parameters of the disease and vitamin D deficiency, no significant correlation was detected. Conclusions: In conclusion, results of the current study implies in the role of vitamin 25(OH)D deficiencies in predicting the course of chronic sarcoidosis. Furthermore, it was concluded that vitamin 25(OH)D deficiency can direct pulmonary sarcoidosis toward stage 2–4 of lung involvements

Land Use Compatibility Assessment Using a Mdified Topsis Model: a Case Study of Elementary Schools in Tehran

Being one of the most controversial issues in urban planning, land use planning has always been in the focus of researches. Land use planning is a subdivision of urban planning which tends to arrange land uses in order to avoid conflicts among them. In order to achieve a transparent and effective urban planning, land uses should be located and allocated in an ideal situation so that avoid negative impacts from neighbouring parcels and land uses. Neighbouring land uses can produce externalities and negative impacts on other land uses because of inter-land use interaction. These externalities may be undesirable effects such as noise, air and visual pollution or may be caused by hazardous facilities. The main objective of this research is to propose a new multi-criteria evaluation model for land use compatibility assessment. Considering the fact that a considerable number of factors affect the compatibility degree of neighbouring land uses, a multi-criteria evaluation approach is employed to address the aforementioned problem. This research employs the integration of Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) and Ordered Weighted Averaging (OWA) methods to facilitate land use compatibility evaluation with respect to optimism degree. The applicability of the proposed model is illustrated by the problem of land use compatibility assessment for elementary schools in Tehran. The results indicate that most of the current schools are situated in a location which is incompatible for the land use type of elementary school especially in the southern and central parts of the city

Heavy metal flocculation at Pirbazar River, Banadar Anzali, south west Caspian Sea

Heavy metal flocculation process was studied in the year 2002 in order to determine the interaction of water in Pirbazar River with Caspian Sea water. The effects of various salinity concentrations of Caspian Sea water were studied on determined heavy metals including Fe, Zn, Pb, Cu, Cd and Cr level of Pirbazar River using APHA method of extraction and measurement. The results illustrated that the level of heavy metal concentration in Pirbazar River were above standard limits and the extent of flocculation depended on both the salinity level and the heavy metal itself. The maximum flocculation for Cd and Cr were recorded at 7.65ppt, for Zn and Fe at 9.35ppt while for Pb and Cd were at 2.55ppt salinity. The order of flocculation with respect to percentage of original concentrations was found to be Zn > Fe > Cr> Cu > Cd> Pb

A survey on surfactant concentration in southern Caspian Sea

We determined concentration of surfactants as mg/I of LAS using Sublation-Methylen Blue method in the south Caspian Sea coastal areas extending from Astara to Bandar-e-Tourkaman. The method was based on the American Standard Method for Examination of Water and Wastewater. We analyzed 53 water samples and found an average surfactant concentration of 0.019mgi1 with the minimum and maximum being 0.008mg/I and 0.038mgi1 respectively. We conclude that presently, surfactant concentration is not critical in the coastal areas. However, care must be exercised interpreting these results considering the synergistic effects between the surfactants and heavy metals and oil hydrocarbons

Simplified on-line monitoring system of MOSFET on-resistance based on a semi-empirical model

This work provides a solution allowing to monitor on-line the health of a power MOSFET adopted in a buck converter. In the considered application, the analysis is focused on the high-side switch, being a low-voltage power MOSFET. The monitoring system allows estimating the on-resistance of the device by measuring both output current and voltage drop across the switch. Moreover, a semi-empirical model is considered in order to account for the dependence of the on-resistance on operating temperature and gate driving voltage. The on-line implementation of such a model allows estimating on-resistance degradation in real-time with a high level of accuracy in a wide range of operating conditions. An on-line calibration procedure is also implemented in order to assess the on-resistance of fresh devices. Experimental results confirm the accuracy of the system (in conjunction with the proposed model) under different operating conditions: load current from 2A to 6A; device temperature up to 100\ub0C and gate to source voltage (VGS) from 6V to 10.5V. In the abovementioned conditions, an accuracy 642.6% is experimentally found. Hence, the system is able to properly estimate the degradation of on-resistance due to ageing conditions