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A New Mathematical Model Towards the Cellular Manufacturing System Considering Multi-Functional Unreliable Machines in Uncertain Environment
, M.Sc. Thesis Sharif University of Technology ; Rafiee, Majid (Supervisor)
Abstract
Cellular Manufacturing System (CMS) is one of the most practical manufacturing systems based on the Group Technology (GT) concept. In this thesis, a CMS is evaluated and analyzed through the proposing new mathematical models. A cellular manufacturing system includes four main sub-problems; Cell formation (CF), Group Scheduling (GS), Group Layout (GL) and Resource Assignment (RA). In this paper two problems of CF and RA are studied and discussed.At first, a new mathematical model is proposed for a CF problem. The objectives are the minimization of inter-intra cell part trips, machine breakdown cost, tool consumption cost and the reconfiguration cost. Multi-functional machines unreliability is...
Aseptic loosening of femoral components - Materials engineering and design considerations
, Article Materials and Design ; Volume 44 , February , 2013 , Pages 155-163 ; 02641275 (ISSN) ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Arumugam, M ; Sharif University of Technology
2013
Abstract
Aseptic loosening is one of the main reasons for the revision of a total knee replacement (TKR). The design of the key component of a TKR, the femoral component, is particularly problematic because its failure can be the result of different causes. This makes the development of new biomaterials for use in the femoral component a challenging task. This paper focuses on the engineering design aspects in order to understand the limitationsof current materials and design deficiencies. The paper describes the introduction of a new biomaterial for a femoral component and justifies the recommendation to use multi-functional materials as a possible solution to aseptic loosening. The potential...
Aseptic loosening of femoral components - A review of current and future trends in materials used
, Article Materials and Design ; Volume 42 , 2012 , Pages 459-470 ; 02641275 (ISSN) ; Sahari, B. B ; Edwards, K. L ; Farahmand, F ; Arumugam, M ; Hong, T. S ; Sharif University of Technology
2012
Abstract
The variety of new biomaterials and different surface treatments being applied to existing materials all intended for total knee replacement (TKR) are self-evident of the demand for longer lasting knee prostheses. Aseptic loosening is one of the main reasons for the revision of TKR components including the femoral component, which has more challenging problems because of the different causes of failure. This paper therefore, focuses on aseptic loosening of femoral components and materials options available. Several current and promising new metallic, ceramic and polymeric biomaterials are discussed to highlight their advantages and their shortcomings. It is concluded that current materials...
Ugi four-component assembly process: An efficient approach for one-pot multifunctionalization of nanographene oxide in water and its application in lipase immobilization
, Article Chemistry of Materials ; Volume 28, Issue 9 , 2016 , Pages 3004-3016 ; 08974756 (ISSN) ; Akhavan, O ; Hashemi, E ; Shamsara, M ; Sharif University of Technology
American Chemical Society
2016
Abstract
Graphene-based materials are revealing the leading edge of advanced technology for their exceptional physical and chemical properties. Chemical manipulation on graphene surface to tailor its unique properties and modify atomic structures is being actively pursued. Therefore, the discovery of robust and general protocols to anchor active functionality on graphene basal plane is still of great interest. Multicomponent reactions promise an enormous level of interest due to addressing both diversity and complexity in combinatorial synthesis, in which more than two starting compounds react to form a product derived from entire inputs. In this article, we present the first covalent...
Design and tailoring of one-dimensional ZnO nanomaterials for photocatalytic degradation of organic dyes: a review
, Article Research on Chemical Intermediates ; Volume 45, Issue 4 , 2019 , Pages 2197-2254 ; 09226168 (ISSN) ; Zirak, M ; Naseri, A ; Kheirabadi, M ; Ebrahimi, M ; Moshfegh, A. Z ; Sharif University of Technology
Springer Netherlands
2019
Abstract
Abstract: Photocatalysis using semiconductors has emerged as a promising wastewater treatment process to overcome the major challenges faced by conventional technologies. The advantages of ZnO nanomaterials over other semiconductors, and their structure-dependent properties, make them important building blocks in nanotechnology as multifunctional materials. Moreover, it has been confirmed that ZnO nanomaterials can exhibit high performance in photodegradation of organic dyes for treatment of industrial effluent. The wurtzite structure of ZnO contains polar and nonpolar planes; the low surface energy and thermodynamic stability of the nonpolar planes enable formation of one-dimensional (1D)...
High-efficiency microwave absorber based on carbon Fiber@La0.7Sr0.3MnO@NiO composite for X-band applications
, Article Ceramics International ; Volume 47, Issue 14 , 2021 , Pages 20438-20446 ; 02728842 (ISSN) ; Li, H ; Niaz Akhtar,, M ; Shi, L ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Carbon fiber (CF) as a multifunctional material with superb performance in aviation industry has serious drawback such as impedance mismatch which restricted the capability of using it as microwave absorber materials. In this research, a novel hierarchical carbon fiber@La0.7Sr0.3MnO@NiO (CF/LS/N) composite was facilely and successfully synthesized via sol-gel and subsequent hydrothermal reactions. The structural, morphological, magnetic and electromagnetic behavior of the composite were precisely evaluated via XRD, FESEM, XPS, VSM and VNA analysis. According to the systematic evaluation results, the synergistic positive effect of adding NiO nanoparticles is revealed in improving the...
A robust optimization approach for a cellular manufacturing system considering skill-leveled operators and multi-functional machines
, Article Applied Mathematical Modelling ; Volume 107 , 2022 , Pages 379-397 ; 0307904X (ISSN) ; Kayvanfar, V ; Mohammadi, A ; Werner, F ; Sharif University of Technology
Elsevier Inc
2022
Abstract
One of the most critical issues in manufacturing systems is the operator management. In this paper, the operator assignment problem is studied within a cellular manufacturing system. The most important novelty of this research is the consideration of operator learning and forgetting effects simultaneously. The skill level of an operator can be increased/decreased based on the time spent on a machine. Moreover, the issues related to operators like hiring, firing, and salaries are considered in the proposed model. The parameters are considered to be uncertain in this model, and a robust optimization approach is developed to handle it. Using this approach, the model solution remains feasible...