Numerical analysis of thermal and composite stresses in prestressed concrete pavements

Fereidoon Moghadas Nejad,Sepehr Ghafari,Shahriar Afandizadeh 사단법인 한국계산역학회 2013 Computers and Concrete, An International Journal Vol.11 No.2

One of the major benefits of the pre-stressed concrete pavements is the omission of tension in concrete that results in a reduction of cracks in the concrete slabs. Therefore, the life of the pavement is increased as the thickness of the slabs is reduced. One of the most important issues in dealing with the prestressed concrete pavement is determination of the magnitude of the pre-stress. Three dimensional finite element analyses are conducted in this research to study the pre-stress under various load (Boeing 777) and thermal gradient combinations. The model was also analyzed under temperature gradients without the presence of traffic loading and the induced stresses were compared with those from theoretical relationships. It was seen that the theoretical relationships result in conservative values for the stress.

Omega-3 Fatty Acids in Health and Disease: Part 2-Health Effects of Omega-3 Fatty Acids in Autoimmune Diseases, Mental Health, and Gene Expression

Fereidoon Shahidi,Homan Miraliakbari 한국식품영양과학회 2005 Journal of medicinal food Vol.8 No.2

Omega-3 fatty acids from marine and plant sources provide a wide range of benefits in several human healthconditions. In vivo studies indicate that omega-3 fatty acids influence the course of several human diseases, including thosethat involve abnormal immune function, mental disorders, and genetic abnormalities in lipid metabolism. Omega-3 fatty acidsare taken up by virtually all body cells and affect membrane composition, eicosanoid biosynthesis, cell signaling cascades,and gene expression. These fatty acids are especially important during human brain development; maternal deficiency ofomega-3 fatty acids may lead to several neurological disorders. The review highlights recent findings on omega-3 fatty acids’influence on autoimmune diseases, mental health, and gene expression.

Omega-3 Fatty Acids in Health and Disease: Part 1 - Health Effects of Omega-3 Fatty Acids in Cardiovascular Disease and Cancer

Fereidoon Shahidi,Homan Miraliakbari 한국식품영양과학회 2004 Journal of medicinal food Vol.7 No.4

The omega-3 polyunsaturated fatty acids have a wide range of beneficial effects in several human health pathologies. Laboratory animal and in-vitro studies have indicated that omega-3 fatty acids affect blood lipid profiles, cardiovascular health, membrane lipid composition, eicosanoid biosynthesis, cell signaling cascades and gene expression. Findings from epidemiological studies suggest that intake of n-3 fatty acids from natural sources or supplements may influence the onset and progression of several disease states including cardiovascular disease and cancer. This review highlights some recent findings in health research that advance our understanding of how omega-3 fatty acids influence cardiovascular health and cancer development.

Phenolic Compounds in Plant Foods : Chemistry and Health Benefits

Marian Naczk,Fereidoon Shahidi 한국식품영양과학회 2003 Preventive Nutrition and Food Science Vol.8 No.2

Phenolic compounds in food and plant materials belong to the simple phenols, phenolic acids, coumarins, flavonoids, stilbenes, tannins, lignans and lignins, all of which are considered as secondary plant metabolites. These compounds may be synthesized by plants during normal development or in response to stress conditions. Phenolics are not distributed uniformly in plants. Insoluble phenolics are components of cell walls while soluble ones are present in vacuoles. A cursory account of phenolics of cereals, beans, pulses, fruits, vegetables and oilseeds is provided in this overview. The information on the bioavailability and absorption of plant phenolics remains fragmentary and diverse. Pharmacological potentials of food phenolics are extensively evaluated. However, there are many challenges that must be overcome in order to fully understand both the function of phenolics in plant as well as their health effects.

An Approach for Managing the Objects in the Internet of Things Using Swarm Intelligence

Davood Vahdat,Fereidoon Shams,Eslam Nazemi 대한산업공학회 2019 Industrial Engineeering & Management Systems Vol.18 No.2

Nowadays the Internet of Things as a new generation of internet and a network that connects everything is highly regarded. There are a large number of devices on the IoT, as well as a high level of heterogeneity that exists between these devices poses challenges, more than ever. One of the most important issues in the IoT in the area of data management is cost reduction of the search. In this regard, clustering objects are considered as a potential solution where in that process, objects with the same action or data content stay on a cluster. In this study, an approach is offered for clustering objects in the IoT environment, with inspiration from the behavior of ants which is called swarm intelligence. Due to the high scalability and distributed nature of ant clustering algorithm (for instance its ability to selforganize), the proposed approach is adapted to the problem. In regards to runtime and accuracy, the results show that the proposed approach functions well, and also it has a high scalability against increasing of the issue’s magnitudes.

Progressive Collapse Analysis of Steel Frames: Simplified Procedure and Explicit Expression for Dynamic Increase Factor

Arash Naji,Fereidoon Irani 한국강구조학회 2012 International Journal of Steel Structures Vol.12 No.4

Progressive collapse refers to a phenomenon in which local damage in a primary structural element leads to total or partial structural system failure. When investigating the progressive collapse of structures, nonlinear dynamic procedures lead to more accurate results than static procedures. However, nonlinear dynamic procedures are very complicated and the evaluation or validation of the results can become very time consuming. Therefore, it is better to use simpler methods. For static analyses,the gravity force applied to the removed column bay should be multiplied by a constant factor of two. However, using a constant dynamic increase factor (DIF) is only appropriate for elastic systems. According to the optimal design of structures,the assumption of elastic behavior after column removal is conservative. Thus, it is necessary to establish an expression for DIF that considers inelastic responses. In this paper, a simplified analysis procedure for the progressive collapse analysis of steel structures is presented using the load displacement and capacity curve of a fixed end steel beam. The results of the proposed method are in good agreement with nonlinear dynamic analysis results. Also, the capacity curve, obtained by dividing the accumulated area under the nonlinear static load displacement curve by the corresponding displacement of the column removed point, is used to predict the progressive collapse resistance of the column removed structure. Finally, an explicit expression for the DIF is established for elastic-perfectly plastic and elastic plastic with catenary action behavior.

Sparsity-aware target localization using TDOA/AOA measurements in distributed MIMO radars

Rouhollah Amiri,Hojatollah Zamani,Fereidoon Behnia,Farokh Marvasti 한국통신학회 2016 ICT Express Vol.2 No.1

In this paper, a sparsity-aware hybrid target localization method in multiple-input-multiple-output (MIMO) radars from time difference of arrival (TDOA) and angle of arrival (AOA) measurements is proposed. This method provides a maximum likelihood estimate of target position by employing compressive sensing techniques. A blockwise approach is addressed in order to achieve better accuracy for a constant computational complexity. The mismatch problem due to grid discretization is also tackled by a dictionary learning technique. The Cramer-Rao lower bound for this model is derived as a benchmark. Numerical simulations are included to corroborate the theoretical developments.

The effect of MWCNTs on the mechanical properties of woven Kevlar/epoxy composites

Iman Taraghi,Abdolhossein Fereidoon,Ali Mohyeddin 국제구조공학회 2014 Steel and Composite Structures, An International J Vol.17 No.6

This manuscript presents an experimental investigation on the effect of multi-walled carbon nanotubes (MWCNTs) addition on the tensile, flexural and impact properties of woven Kevlar fabric reinforced epoxy composites. MWCNTs were dispersed in the epoxy resin by sonication technique and the samples were fabricated by hand layup laminating procedure. Scanning electron microscopy (SEM) was used to characterize the microstructure of produced samples. The effects of adding small amounts (≤ 1%) of MWCNT on the tensile, flexural and impact (Izod) behaviors of laminated composites were analyzed. Results revealed that MWCNTs enhanced the Young's modulus up to 20%, bending modulus up to 40%, and impact strength up to 45% in comparison with woven Kevlar fabric/epoxy composites. It was found that the maximum improvements in mechanical properties were happened for 0.5 wt.% MWCNT.

Why Dynamic Security for the Internet of Things?

Seyyed Yasser Hashemi,Fereidoon Shams Aliee 한국정보과학회 2018 Journal of Computing Science and Engineering Vol.12 No.1

The Internet of Things (IoT) ecosystem potentially includes heterogeneous devices with different processing mechanisms as well as very complicated network and communication models. Thus, analysis of data associated with adverse conditions is much more complicated. Moreover, mobile things in the IoT lead to dynamic alteration of environments and developments of a dynamic and ultra-large-scale (ULS) environment. Also, IoT and the services provided by that are mostly based on devices with limited resources or things that may not be capable of hosting conventional controls. Finally, the dynamic and heterogeneous and ULS environment of the IoT will lead to the emergence of new security requirements. The conventional preventive and diagnostic security controls cannot sufficiently protect it against increasing complication of threats. The counteractions provided by these methods are mostly dependent on insufficient static data that cannot sufficiently protect systems against sophisticated and dynamically evolved attacks. Accordingly, this paper investigates the current security approaches employed in the IoT architectures. Moreover, we define the dynamic security based on dynamic event analysis, dynamic engineering of new security requirements, context awareness and adaptability, clarify the need for employment of new security mechanism, and delineate further works that need to be conducted to achieve a secure IoT.

Why Dynamic Security for the Internet of Things?

Hashemi, Seyyed Yasser,Aliee, Fereidoon Shams Korean Institute of Information Scientists and Eng 2018 Journal of Computing Science and Engineering Vol.12 No.1

The Internet of Things (IoT) ecosystem potentially includes heterogeneous devices with different processing mechanisms as well as very complicated network and communication models. Thus, analysis of data associated with adverse conditions is much more complicated. Moreover, mobile things in the IoT lead to dynamic alteration of environments and developments of a dynamic and ultra-large-scale (ULS) environment. Also, IoT and the services provided by that are mostly based on devices with limited resources or things that may not be capable of hosting conventional controls. Finally, the dynamic and heterogeneous and ULS environment of the IoT will lead to the emergence of new security requirements. The conventional preventive and diagnostic security controls cannot sufficiently protect it against increasing complication of threats. The counteractions provided by these methods are mostly dependent on insufficient static data that cannot sufficiently protect systems against sophisticated and dynamically evolved attacks. Accordingly, this paper investigates the current security approaches employed in the IoT architectures. Moreover, we define the dynamic security based on dynamic event analysis, dynamic engineering of new security requirements, context awareness and adaptability, clarify the need for employment of new security mechanism, and delineate further works that need to be conducted to achieve a secure IoT.