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Characterisation of Melt Spun Ni-Ti Shape Memory Ribbons’ Microstructure
Kambiz Mehrabi,Mihael Brunˇcko,Albert C. Kneiss,Miodrag ˇColiˇc,Dragoslav Stamenkovic,Janko Ferˇcec,Ivan Anžel,Rebeka Rudolf 대한금속·재료학회 2012 METALS AND MATERIALS International Vol.18 No.3
NiTi alloys are the most technologically important medical Shape Memory Alloys in a wide range of applications used in Orthopaedics, Neurology, Cardiology and interventional Radiology as guide-wires,self-expandable stents, stent grafts, inferior vena cava filters and clinical instruments. This paper discusses the use of rapid solidification by the melt spinning method for the preparation of thin NiTi ribbons for medical uses. Generally, the application of rapid solidification via melt-spinning can change the micro-structure drastically, which improves ductility and shape memory characteristics and leads to samples with small dimensions. As the increase in the wheel speed led to a reduced ribbon thickness, the cooling rate increased and, therefore, the martensitic substructure became finer. Furthermore, no transition from the crystalline phase to the amorphous phase was obtained by increasing the cooling rate, even at a wheel speed of 30 m/s. Specimens for our metallographic investigation were cut from the longitudinal cross sec-tions of melt-spun ribbons. Conventional TEM studies were carried out with an acceleration voltage of 120 kV. Additionally, the chemical composition of the samples was examined with a TEM equipped with an EDX analyser. The crystallographic structure was determined using Bragg-Brentano x-ray diffraction with Cu-Kα radiation at room temperature.
Kambiz Takin,Behrokh H. Hashemi,Masoud Nekooei 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.4
In an actual design, none of the structures with shear behaviors will be designed for torsional moments. Any failure or damages to roofs, infills, shear walls, and braces caused by an earthquake, will inevitably result in relocation of center of mass and rigidity of the structure. With these changes, the dynamic characteristics of structure could be changed during an earthquake at any moment. The main objective of this paper is to obtain the relationship between time-varying eccentricity of load and corner lateral displacement. In this study, various methods have been used to determine the structural response for time-varying lateral corner displacement. As will be seen below, some of the structural calculation methods result in a significant deviation from the actual results, although these methods include the interaction effects of modes. Controlling the lateral displacement of structure can be performed in different ways such as, passive dampers, friction dampers, semi-active systems including the MR damper and active Systems. Selecting and locating these control systems is very important to bring the maximum safety with minimum cost into the structure. According to this study will be show the relation between the corner lateral displacements of structure and time-varying eccentricity by different kind of methods during an earthquake. This study will show that the response of the structure at the corners due to an earthquake can be very destructive and because of changing the eccentricity of load, calculating the maximum possible response of system can be carried out by this method. Finally, some kind of systems must be used for controlling these displacements. The results shows that, the CQC, DSC and exact methods is comply each other but the results of Vanmark method is not comfortable for these kind of buildings.
Strengthening of steel hollow pipe sections subjected to transverse loads using CFRP
Kambiz Narmashiri,Ghadir Mehramiz 국제구조공학회 2016 Structural Engineering and Mechanics, An Int'l Jou Vol.60 No.1
Nowadays using Carbon Fiber Reinforced Polymer (CFRP) has been expanded in strengthening steel structures. Given that few studies have taken about strengthening of steel hollow pipe sections using CFRP, in present study, the effects of CFRP sheets using two layers as well as in combination with additional reinforcing strips has been assessment. Strengthening of five specimens was carried out in laboratory tests. As well as numerical simulation was performed for all specimens by Finite Element Method (FEM) using ABAQUS software and high correlation between the results of numerical models with experimental data indicate the power of FEM in this field. The results of both laboratory and simulated specimens showed that load-bearing capacity of circular cross-sections can be significantly increased using CFRP retrofitting technique. Also, application of additional CFRP reinforcing strips and layers caused more strength for the strengthened specimens.
Kambiz Mokhtari,Mehrdad Behforouzi,Kawkab Abdul Aziz Mohammed Al Balush,Hamidreza Soltani,Norhan Ibrahim 국제이네비해양경제학회 2020 International Journal of e-Navigation and Maritime Vol.15 No.1
In the maritime industry, most perceptions, frameworks and methodologies of dealing with hazards are for their risk assessment rather than their risk management. This tendency discloses the reality that within the maritime sectors in areas like shipping, logistics, oil and gas there is a lack of coherent Quantitative Risk Management (QRM) methodology from which to understand the risk-based decisions especially for appropriate risk management such as in seaports’ terminals. Therefore, in this paper initially, during priority assessment of the identified hazards, Fuzzy Set Theory was applied to handle imprecision of the uncertain risk-based statistics to get an accurate result. In the next stage, Fuzzy Fault Tree and Fuzzy Event Tree methods were used to achieve the sequence of quantitative risk analysis. In the final step, a Fuzzy Technique for Order of Preference by Similarity to Ideal Solution tool was used for the implementation of the mitigation phase to complete and conclude the proposed QRM cycle.
Converting sports diplomacy to diplomatic outcomes: Introducing a sports diplomacy model
Kambiz Abdi,Mahdi Talebpour,Jami Fullerton,Mohammad Javad Ranjkesh,Hadi Jabbari Nooghabi 한국외국어대학교 국제지역연구센터 2018 International Area Studies Review Vol.21 No.4
As sport has become an integral part of society, it has also become a tool for diplomacy around the world. The purpose of this study is to introduce a sports diplomacy model and identify “the critical abilities” for converting sport soft power tools into resources for diplomatic outcomes. The data for this research comprise 30 online surveys completed by international experts in the fields of sports and public diplomacy. The responses were qualitatively analyzed using the fuzzy Delphi method (FDM). After running two rounds of fuzzy Delphi, two main strategies for sports diplomacy emerged—maintaining “official and sports diplomacy solidarity” and using sport figures as “competent cultural ambassadors.” The proposed model includes the most applicable sports diplomacy resources, the most expected diplomatic outcomes, and the major conversion tools (skillful strategies) in the viewpoint of sports and public diplomacy experts. The application of the model finds that states can expect diplomatic outcomes if appropriate sports diplomacy resources and conversion strategies are implemented in an orderly, innovative and accurate manner.
UV-cured coating of citric acid onto polypropylene film as an antioxidant clean label
Kambiz Sadeghi,Hanseul Kim,Hojun Shin,Jongchul Seo 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10
The interface modification of inert materials, such as packaging materials, tends to introduce new functions to materials’ surface while maintaining the bulk performance. Herein, citric acid (CA) as a biochelator was immobilized on the surface of polypropylene (PP) film. To this end, glycidyl methacrylate (GMA) was photochemically polymerized onto PP film surface in the presence of benzophenone at 365 nm. Afterward, CA was immobilized on PP-g-GMA film surface through a ring-opening reaction between the oxirane ring of the PP-g-GMA film and CA. FTIR, XPS, and 13C-NMR detected chemistry change after UV-grafting of GMA and CA immobilization. Additionally, a large amount of carboxylic acid (215±11 nM) was detected on the surface of PP-g-GMA-g-CA biochelator film, which chelated 215±11 nM of Fe<SUP>3+</SUP> as a peroxidant. This biochelator film extended the lag time of vitamin C degradation and olive oil oxidation, which in turn showed an antioxidant feature after incubation with different food matrices. The overall migration and ligand stability tests confirmed non-migratory feature of this biochelator film that can practically realize the clean label in packaging science.
Numerical and analytical investigation of cyclic behavior of D-Shape yielding damper
Kambiz Cheraghi,Mehrzad TahamouliRoudsari,Sasan Kiasat,Kaveh Cheraghi 국제구조공학회 2024 Structural Engineering and Mechanics, An Int'l Jou Vol.89 No.4
The purpose of this research was to investigate the cyclic behavior of the D-shaped dampers (DSD). Similarly, at first, the numerical model was calibrated using the experimental sample. Then, parametric studies were conducted in order to investigate the effect of the radius and thickness of the damper on energy dissipation, effective and elastic stiffness, ultimate strength, and equivalent viscous damping ratio (EVDR). An analytical equation for the elastic stiffness of the DSD was also proposed, which showed good agreement with experimental results. Additionally, approximate equations were introduced to calculate the elastic and effective stiffness, ultimate strength, and energy dissipation. These equations were presented according to the curve fitting technique and based on numerical results. The results indicated that reducing the radius and increasing the thickness led to increased energy dissipation, effective stiffness, and ultimate strength of the damper. On the other hand, increasing the radius and thickness resulted in an increase in EVDR. Moreover, the ratio of effective stiffness to elastic stiffness also played a crucial role in increasing the EVDR. The thickness and radius of the damper were evaluated as the most effective dimensions for reducing energy dissipation and EVDR.