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- 저자 : Mortaheb, Mohammad Mehdi (검색결과 4 건)
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H.R. Mortaheb,M. Baghban Salehi,M. Rajabzadeh 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.99 No.-
Hybrid membranes consisting of polyvinylidenefluoride (PVDF) and electrochemically-fabricatedgraphene were prepared via phase inversion technique. The important parameters in manufacturingunfilled PVDF membranes including polymer concentration and content of additives were initiallyassessed. The effects of adding graphene to the PVDF membrane on its performance for desalination of a3.5 wt% NaCl solution were then investigated using an air gap membrane distillation setup. Thesimultaneous effects of three individual parameters in membrane preparation including ethanolconcentration in the coagulation bath, the coagulation bath temperature, and graphene content onmembrane characteristics such as contact angle, porosity, and permeationflux were investigated. Byincreasing ethanol concentration in the coagulation bath and graphene content in the polymeric solution,the contact angle and thus hydrophobicity of the membrane were increased. Also, by increasing graphenecontent up to 0.5 wt%, the membrane permeationflux was increased while further increase in thegraphene content resulted in decrease in the permeationflux. It was found that coagulation bathtemperature has the highest effect on the membrane porosity. The parameters for manufacturingoptimum membrane were determined by experimental design. The optimum membrane could yield apermeationflux of 3.54 kg m 2 h 1 and a salt rejection of 99.88%, which are in good agreement with thepredicted results. The performance of optimized membrane was superior to those by PVDF and GO/PVDFmembranes reported previously in literature.
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Comparative Study of GPS-Integrated Concrete Supply Management using Discrete Event Simulation
Zekavat, Payam Rahnamayie,Mortaheb, Mohammad Mehdi,Han, Sangwon,Bernold, Leonhard Korea Institute of Construction Engineering and Ma 2014 Journal of construction engineering and project ma Vol.4 No.2
The management of vehicular supply of "perishable" construction material, such as concrete mixes, faces a series of uncertainties such as weather, daily traffic patterns and accidents. Presented in this paper is a logistics control model for managing a hauling fleet with interrelated processes at both ends and queue capacities. Discrete event simulation is used to model the complex interactions of production units and the randomness of the real world. Two alternative strategies for ready mix concrete delivery, with and without an off-site waiting queue, are studied to compare supply performance. Secondly, the paper discusses the effect of an agent-based GPS tracking system providing real-time travel data that lessens the uncertainty of trucking time. The results show that the combination of GPS information with off-site queuing reduces productivity loss and process wastes of concrete placement as well as the idleness of supply trucks when crew or pump experience an unexpected stoppage.
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Causes of Common and Frequent Claims in Oil, Gas and Petrochemical Projects of Iran
S. H. Hasheminasab,M. M. Mortaheb,A. Ahmadian F. F. 대한토목학회 2014 KSCE JOURNAL OF CIVIL ENGINEERING Vol.18 No.5
Over recent years, frequent involvements in claims have been inevitable due to unpredictable economic changes and increasingcomplexities in construction industry. Therefore, even appropriately made contracts are not exempted from claims. On the otherhand, construction contract claims are time-consuming, expense-involving and most likely leading to unsatisfactory results. However, there may be some positive outcomes, such as time extension or compensation of damages. To launch investigations, a listof important and frequent claims in oil and gas industry projects of Iran was extracted after a succinct documents review. Further, themost important claim causes were identified through conducting a questionnaire survey among contractors, consultants, owners andlawyers involved in such projects. Reliability of responses has been examined, accordingly. The study reveals that the external riskslike political, social, cultural and economical issues are the most important causes for claims in this industry. Moreover, inadequatefinancial resources on the part of owner and contractor, failure in performing contractor’s obligations and vague contract conditionsresulted in formation of different interpretations; are some of the most important root causes of claims in this context.
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Assessing Lifecycle Success of Petrochemical Projects–based on Client’s Viewpoint
M. Shariatfar,H. Beigi,M. M. Mortaheb 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.1
For the last couple of decades, researchers/managers have realized that the traditional success criteria known as golden triangle (time, cost, quality) are not adequate measures to align a project with the long term success trend of a company. The perception of project success may differ from one industry to another or from one stakeholder (client, contractor, etc.) to other. Petrochemical projects are of high complexity and a vast variety of parameters needs to be monitored in order to produce on spec products according to the customer requirements and market dynamic changes. To be successful in such complex projects, it is required to be successful in every phase of the project lifecycle. In this study, project success has been linked to four dimensions (efficiency, business success, impact and future preparation) and is investigated from client's point of view. Based on a list of success criteria, previously recognized important by other researchers, a set of novel categorizations of the success criteria has been developed, called Success Breakdown Structure (SBS). The relative importance of each success criterion is measured by means of a survey questionnaire. It was found that almost all success criteria are important for clients and the efficiency dimension of success plays the most important role in the long term success achievement in client’s organization.
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