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Esmaeil Emadoddi,Majed Zabihi,Fathallah Qods 대한금속·재료학회 2020 METALS AND MATERIALS International Vol.26 No.1
In this present study, Aluminum with 1, 3, 5 and 7 vol% alumina composites were produced via powder metallurgy andvacuum sintering techniques, then were followed by simple shear extrusion (SSE) process. Four SSE dies with differentdistortion angles (α) were used in experimental works. The SSE-ed samples with α = 22.5° and 30° were failed whereas theSSE-ed samples with α = 8° and 10° were deformed up to three passes, successfully. Porosity measurements were carriedout by Archimedes method and microstructure evaluation of the specimens was accomplished using optical and scanningelectron microscopy. Mechanical behavior of processed samples was investigated by shear punch test, and hardness measurements. It was understood that the SSE-ed samples have good bonding at aluminum/alumina interface. It was found thatby increasing the number of SSE passes, ultimate shear strength and hardness were increased. The percentage of shearelongation and porosity content were decreased. Moreover, when the amount of α was increased, the shear strength for allsamples was improved.
Esmaeil Karami,Mojtaba Alishahi,Taravat Molayemraftar,Masoud Ghorbanpour,Mohammad Reza Tabandeh,Takavar Mohammadian 한국수산과학회 2019 Fisheries and Aquatic Sciences Vol.22 No.4
Background: Lactococcus garvieae is one of the most important risk factors in the rainbow trout culture. Therefore, the purpose of this study was to identify and detect strains isolated from rainbow trout suspected of having Lactococcus garvieae using biochemical characteristics and PCR and determination of the degree of severity of isolated strains. Methods: In this study, the cause of lactococcosis in selected rainbow trout farms in Kohkilooieh and Boyerahmad province was assayed. Gram-positive and catalase-negative bacterial isolates were first obtained from selected trout fish farms using conventional biochemical tests and PCR assay. The 10-day LD50 method (concentration causing 50% mortality in 10 days) was used to determine the severity of the isolated bacteria. Results: One bacterial isolate was detected from all sampled fish which confirmed as Lactococcus garvieae using a specific PCR assay based on the 16S rDNA gene by producing a single band of 1107 bp. Analysis of the rate of mortality showed that the 10-day LD50 was 4.6 × 105 CFU/fish. The results of this study showed that isolated bacteria had high severity for rainbow trout. The presence of bacteria in internal organs of suspected fish showed a severe systemic infection in challenged fish. Antibiogram assay also indicated that the isolated Lactococcus garvieae were resistant to some mostly used antibiotics in rainbow trout. Conclusions: According to current research, it can be concluded that the condition of lactococcosis in the studied area is not suitable, and despite the presence of disease, there is no proper action to control and prevent the disease. Unfortunately, isolated bacteria from the studied area have a very high severity compared to bacteria isolated from other regions of the country or other countries. Therefore, further investigation is needed to determine the cause of this difference and possibly in the design of the vaccine.
Esmaeil Shirazi,Yogendra P. Chaubey,Hassan Doosti,Hossein Ali Nirumand 한국통계학회 2012 Journal of the Korean Statistical Society Vol.41 No.2
We consider wavelet based method for estimating derivatives of a density via block thresholding when the data obtained are randomly right censored. The proposed method is analogous to that of Hall and Patil (1995) for density estimation in the complete data case that has been extended recently by Li (2003, 2008). We find bounds for the L2-loss over a large range of Besov function classes for the resulting estimators. The results of Hall and Patil (1995), Prakasa Rao (1996) and Li (2003, 2008) are obtained as special cases and the performance of the proposed estimator is investigated by a numerical study.
Generalized Synchronization of Non-Identical Chaotic Systems with Minimum Control Effort
Esmaeil Alibeiki,Mohammad Haeri 제어로봇시스템학회 2008 제어로봇시스템학회 국제학술대회 논문집 Vol.2008 No.10
In synchronization of identical chaotic systems, the control cost would be optimal in the sense that it would be zero when the synchronization is occurred. Based on this idea, in synchronization of non-identical chaotic systems, we find a signal function added to states of the derive system so that it makes the dynamics of the drive system translated into dynamics of the response system. After synchronizing two systems using this function, states of the response system will be synchronized with the equivalent states and the control cost will be optimal similar to those in the identical synchronization.
Esmaeil Ghorbani,Mehdi Keshmiri 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.7
Wind turbines, helicopters, and turbo-machineries’ rotary motion, along with a variety of nonlinear structures linearized with their periodic limit cycles, may all contain time-periodic terms in their equations of motion even if the equations remain linear. The purpose of this study is to model these systems into a beam-moving mass system. Natural frequencies of the beam are calculated using past work in which pseudo-natural frequencies of a beam-moving mass system were extracted, followed by the homotopy perturbation method. The findings of this study are valuable to the industry, and they decrease error margin in resonance range assessment. This approach indicates that for beam-moving mass systems, extraction of natural frequencies that ignore the moving mass effect can lead to inaccurate results, whereas only a limited amount of physical data are needed obtain accurate calculations. Furthermore, this study used homotopy perturbation for operational modal analysis purposes and not for solving nonlinear equations.
Cross-Linked Collagen Scaffold from Fish Skin as an Ideal Biopolymer for Tissue Engineering
Esmaeil Biazar,Mahshad Kamalvand,Saeed Heidari Keshel,Bahareh Pourjabbar,Mustafa Rezaei-Tavirani 한국재료학회 2022 한국재료학회지 Vol.32 No.4
Collagen is one of the most widely used biological materials in medical design. Collagen extracted from marine organisms can be a good biomaterial for tissue engineering applications due to its suitable properties. In this study, collagen is extracted from fish skin of Ctenopharyngodon Idella; then, the freeze drying method is used to design a porous scaffold. The scaffolds are modified with the chemical crosslinker N-(3-Dimethylaminopropyl)-N'-ethyl carbodiimide hydrochloride (EDC) to improve some of the overall properties. The extracted collagen samples are evaluated by various analyzes including cytotoxicity test, SDS-PAGE, FTIR, DSC, SEM, biodegradability and cell culture. The results of the SDS-PAGE study demonstrate well the protein patterns of the extracted collagen. The results show that cross-linking of collagen scaffold increases denaturation temperature and degradation time. The results of cytotoxicity show that the modified scaffolds have no toxicity. The cell adhesion study also shows that epithelial cells adhere well to the scaffold. Therefore, this method of chemical modification of collagen scaffold can improve the physical and biological properties. Overall, the modified collagen scaffold can be a promising candidate for tissue engineering applications.
Dynamic response of layered hyperbolic cooling tower considering the effects of support inclinations
Esmaeil Asadzadeh,Mehtab Alam,Sahebali Asadzadeh 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6
Cooling tower is analyzed as an assembly of layered nonlinear shell elements. Geometric representation of the shell is enabled through layered nonlinear shell elements to define the different layers of reinforcements and concrete by considering the material nonlinearity of each layer for the cooling tower shell. Modal analysis using Ritz vector analysis and nonlinear time history analysis by direct integration method have been carried out to study the effects of the inclination of the supporting columns of the cooling tower shell on its dynamic characteristics. The cooling tower is supported by I-type columns and ᴧ-type columns supports having the different inclination angles. Relevant comparisons of the dynamic response of the structural system at the base level (at the junction of the column and shell), throat level and at the top of the tower have been made. Dynamic response of the cooling tower is found to be significantly sensitive to the change of the inclination of the supporting columns. It is also found that the stiffness of the structure system increases with increase in inclination angle of the supporting columns, resulting in decrease of the period of the structural system. The participation of the stiffness of the tower in structural response of the cooling tower is fund to be dependent of the change in the inclination angle and even in the types of the supporting columns.
Esmaeil Jorjani,Saeed Chehreh Chelgani,Amir Hossein Bagherieh 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2
The extraction of rare earth elements from apatite concentrate of Chadormalu plant of Iran was studied with the dissolution of ore in nitric acid. The parameters of acidity: 60%, solid to liquid ratio: 30%, leaching time: 30minute, agitation rate: 200 rpm, temperature: 60℃ and particle size (d_80): 50 microns were determined as the optimum operational conditions. The recoveries of lanthanum, cerium, neodymium and yttrium were achieved at 74, 59, 72 and 73%, respectively, in the optimized conditions. Multivariable regression was used to predict La, Ce, Nd, Y and total REEs (Y+Nd+Ce+La) leaching recoveries, using experimental data from laboratory studies. It was achieved quite satisfactory correlations of 0.93, 0.98, 0.99, 0.97 and 0.99 for the prediction of Y, Nd, Ce, La and total REEs recoveries,respectively. It was shown that the proposed equations accurately reproduce the effects of operational variables on the different REEs recoveries, and can be used to optimize the REEs leaching plant.
Esmaeil Mahmoudi,Badraldin Ebrahim Sayed Tabatabaei,Vittorio Venturi 한국식물병리학회 2011 Plant Pathology Journal Vol.27 No.3
Several soil bacteria were found to degrade N-Acylhomoserine lactones (NAHLs), thereby interfering with the bacterial quorum sensing system. In this research,fifteen strains of NAHL degrading rhizobacteria were isolated from potato rhizosphere. Based on phenotypic characteristics and 16S rDNA sequence analyses, the strains were identified as members of genera Bacillus,Streptomyces, Arthrobacter, Pseudomonas and Mesorhizobium. All tested isolates were capable to degrade both synthetic and natural NAHL produced by Pectobacterium carotovorum subsp. carotovorum (Pcc) strain EMPCC. In quorum quenching experiments selected isolates, especially Mesorhizobium sp., were markedly reduced the pathogenicity of Pcc strain EMPCC in potato tubers and totally suppressed tissue maceration on potato tubers. These led to consider the latter as a useful biocontrol agent against Pectobacterium spp.