215 research outputs found

    The Effects of Using Different Seismic Bearing on the Behavior and Seismic Response of High-Rise Building

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    The effects of using different seismic bearings were investigated to reduce the seismic response of buildings by assuming the vulnerability of 20-story regular RC building in this paper. The method of this study was that the studied building was studied in three different models in terms of its connection to the foundation. In the first model, the structures were placed on the rigid bearing and in the second and third models; lead-rubber bearings and friction pendulum bearings were placed at the counter between the structure and foundation, respectively. Then, the dynamic analysis was used to assess the behaviour and seismic response of the mentioned models. The results of the study showed that the structures in the first model functioned like cantilever column that would become uniaxial and biaxial bending under the effects of earthquake around the vertical axis of structure. Due to the tensile (tension) weakness in concrete, seismic loads caused major cracks in the tension part of the structures according to the place of the neutral axis that could lead to the collapse of structure. In addition, the use of mentioned seismic bearings under the earthquake caused the structure like a semi-rigid box slid on this equipment that reduced the structure's stiffness and increased the period of the structure in comparison with the first model. Using the studied seismic bearings caused the displacement of the roof of the first and twentieth stories of the structure become approximately equal and prevented the creation of the bending moment in the first model. The results of non-linear time history analysis showed that using the studied seismic bearings caused the response of the structure reduced significantly when the structure was placed on rigid bearings. It could be very valuable regarding the limitation of the capacity of the structure's members

    A Novel Hybrid Framework for Co-Optimization of Power and Natural Gas Networks Integrated With Emerging Technologies

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    In a power system with high penetration of renewable power sources, gas-fired units can be considered as a back-up option to improve the balance between generation and consumption in short-term scheduling. Therefore, closer coordination between power and natural gas systems is anticipated. This article presents a novel hybrid information gap decision theory (IGDT)-stochastic cooptimization problem for integrating electricity and natural gas networks to minimize total operation cost with the penetration of wind energy. The proposed model considers not only the uncertainties regarding electrical load demand and wind power output, but also the uncertainties of gas load demands for the residential consumers. The uncertainties of electric load and wind power are handled through a scenario-based approach, and residential gas load uncertainty is handled via IGDT approach with no need for the probability density function. The introduced hybrid model enables the system operator to consider the advantages of both approaches simultaneously. The impact of gas load uncertainty associated with the residential consumers is more significant on the power dispatch of gas-fired plants and power system operation cost since residential gas load demands are prior than gas load demands of gas-fired units. The proposed framework is a bilevel problem that can be reduced to a one-level problem. Also, it can be solved by the implementation of a simple concept without the need for Karush–Kuhn–Tucker conditions. Moreover, emerging flexible energy sources such as the power to gas technology and demand response program are considered in the proposed model for increasing the wind power dispatch, decreasing the total operation cost of the integrated network as well as reducing the effect of system uncertainties on the total operating cost. Numerical results indicate the applicability and effectiveness of the proposed model under different working conditions

    Day-Ahead Network-Constrained Scheduling of CHP and Wind Based Energy Systems Integrated with Hydrogen Storage Technology

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    The integration of renewable energy sources is vastly increased in recent decades considering environmental concerns and lack of fossil fuels. Such integration has appeared novel challenges in electrical energy systems according to their uncertain nature. The hydrogen energy storage (HES) system plays a significant role is power systems by converting extra wind power to the hydrogen using power to hydrogen (P2H) technology. In addition, the emerging technologies such as combined heat and power (CHP) units are effective in increasing the efficiency of power systems. This work presents a day-ahead scheduling scheme for CHP-HES based electrical energy networks with high integration of wind power sources. The effectiveness of the presented model is investigated by implementation on the IEEE 6-bus system. The impact of heat load increment has been studied on scheduling of generation plants, wind power dispatch and operation cost of the system. The simulation results prove that operation cost of the system and wind power curtailment have been decreased using the HES technology

    Effect of metabolic syndrome and its components on survival in colorectal cancer: a prospective study.

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    INTRODUCTION Metabolic syndrome (MetS) may affect prognosis of the patients diagnosed with colorectal cancer (CRC). OBJECTIVES This study was aimed to design a model and to examine the prognostic effect of MetS on survival time in the patients with CRC. PATIENTS AND METHODS Data were collected from 1127 cases of CRC from Cancer Registry Center of the Research Institute of Gastroenterology and Liver Disease, Shahid Beheshti University of Medical Sciences, Tehran, Iran. In this cohort study, patients were divided into two groups based on the presence of MetS. We tested the prognostic value of MetS in the patients by Cox proportional hazard modeling. RESULTS Mean ± standard deviation of the patients' age at diagnosis in MetS group and non-MetS group was 56 ± 13 years old and 53 ± 15 years old respectively. Tumor stage as an independent variable affected CRC survival. The mean survival time of the MetS and non-MetS groups was 23 and 27 months respectively. Independent variables like tumor stage (hazard ratio [HR], 1.76; 95% CI, 0.29-0.90) and educational level (HR, 0.50; 95% CI, 0.23-0.97) had significant effect on CRC survival and MetS (HR, 0.95; 95% CI, 0.52-1.5), tumor size (HR, 1.390; 95% CI, 1.237-1.560), family history, age, gender, and smoking had non-significant effect on CRC survival. CONCLUSION MetS could be a prognostic factor for survival in the patients with CRC. The results suggested that effect of MetS was not significant

    An In vitro Comparison of Apically Extruded Debris Using Reciproc, ProTaper Universal, Neolix and Hyflex in Curved Canals

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    Introduction: As a consequence of root canal preparation, dentinal chips, irrigants and pulp remnants are extruded into preradicular space. This phenomenon may lead to post endodontic flare-ups. The purpose of this study was to compare the amount of extruded debris with four endodontic NiTi engine-driven systems. Methods and Materials: Sixty mesiobuccal roots of maxillary molars with 15-30˚ curvature were divided randomly into four groups (n=15). Each group was instrumented up to apical size of 25 using Reciproc, ProTaper Universal, Neolix and Hyflex. Bidistilled water was used as irrigant and extruded debris was collected in pre-weighted Eppendorf tubes. Tubes were stored in incubator for drying the debris. Extruded debris were weighted in electronic microbalance with accuracy of 0.0001 g. The raw data was analyzed with one way analysis of variance (ANOVA) and Tukey’s HSD post hoc test. Level of significance was set at 0.05. Results: The debris extrusion with Reciproc files was significantly higher than the other groups (P<0.05). Hyflex significantly extruded less debris than other files (P<0.05). There was no significant difference between ProTaper Universal and Neolix regarding the amount of extruded debris (P=0.98). Conclusion: All systems extruded debris during the instrumentation. Reciproc system significantly extruded more debris. Caution should be taken when interpreting the results of this study and applying it to the real clinical situation.Keywords: Controlled Memory; Debris Extrusion; Reciprocating; Root Canal Preparation; Rotary Instrumentatio

    Interventions based on PRECEDE-PROCEED for promoting safety behaviors in Primary school boys

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    Introduction & Objective: Pedestrian injuries are a significant source of morbidity, mortality and disability among children. Prevention of these injuries is thus a major priority for public health and requires a comprehensive approach and educational strategies. The purpose of this study was designing and evaluation of an educational program, based on the PRECEED-PROCEED model for improvement of safety behavior in primary school boys. Materials & Methods: This study is a field trial carried out in 6th areas of Tehran in 2007. Participants (n=88) were 10 – 11 year old who followed by items measuring the PRECEED-PROCEED model before and after two months of intervention. The collected data were analyzed with T test, X2 and pair T test using SPSS software. Results: After participating in educational program, significant improvements were found in knowledge, attitude, behavior, enabling and reinforcing factors of the components of PRECEEDPROCEED model. Conclusion: The findings suggest the beneficial effects of educational intervention based on the PRECEDE-PROCEED model on improving the safety behavior. It can be recommended that health education plan be used on educational models

    Femtosecond photonic viral inactivation probed using solid-state nanopores

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    We report on detection of virus inactivation using femtosecond laser radiation by measuring the conductance of a solid state nanopore designed for detecting single particles. Conventional methods of assaying for viral inactivation based on plaque forming assays require 24–48 h for bacterial growth. Nanopore conductance measurements provide information on morphological changes at a single virion level.We show that analysis of a time series of nanopore conductance can quantify the detection of inactivation, requiring only a few minutes from collection to analysis. Morphological changes were verified by dynamic light scattering. Statistical analysis maximizing the information entropy provides a measure of the log reduction value. This work provides a rapid method for assaying viral inactivation with femtosecond lasers using solid-state nanopores.First author draf

    Solving Incomplete Datasets in Soft Set Using Supported Sets and Aggregate Values

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    AbstractThe theory of soft set proposed by Molodtsovin 1999[1]is a new method for handling uncertain data and can be defined as a Boolean-valued information system. Ithas been applied to data analysis and decision support systems based on large datasets. In this paper, it is shown that calculated support value can be used to determine missing attribute value of an object. However, in cases when more than one value is missing, the aggregate values and calculated support values will be used in determining the missing values. By successfully recovering missing attribute values, the integrity of a dataset can still been maintained
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