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Search Results: 1 - 10 of 78 matches for " Heshmat Noei "
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Catalytic Behaviour of Mesoporous Cobalt-Aluminum Oxides for CO Oxidation
Ankur Bordoloi,Miguel Sanchez,Heshmat Noei,Stefan Kaluza,Dennis Gro?mann,Yuemin Wang,Wolfgang Grünert,Martin Muhler
Journal of Catalysts , 2014, DOI: 10.1155/2014/807545
Abstract: Ordered mesoporous materials are promising catalyst supports due to their uniform pore size distribution, high specific surface area and pore volume, tunable pore sizes, and long-range ordering of the pore packing. The evaporation-induced self-assembly (EISA) process was applied to synthesize mesoporous mixed oxides, which consist of cobalt ions highly dispersed in an alumina matrix. The characterization of the mesoporous mixed cobalt-aluminum oxides with cobalt loadings in the range from 5 to 15?wt% and calcination temperatures of 673, 973, and 1073?K indicates that Co2+ is homogeneously distributed in the mesoporous alumina matrix. As a function of the Co loading, different phases are present comprising poorly crystalline alumina and mixed cobalt aluminum oxides of the spinel type. The mixed cobalt-aluminum oxides were applied as catalysts in CO oxidation and turned out to be highly active. 1. Introduction Supported metal oxide catalysts have attracted much attention in recent years due to their widespread applicability in industrially and academically important reactions. The extent and nature of the interaction, dispersion, and reducibility of the metal oxides depend on the synthesis method, loading, calcination temperature, and time. Cobalt supported on alumina is a typical catalyst, which is specially important for Fischer-Tropsch synthesis. Conventionally, the preparation of cobalt catalysts is performed by incipient wetness impregnation using suitable cobalt precursors on commercial alumina at low pH. Weak interaction is normally observed between the positively charged alumina carrier and the cobalt cations resulting in relatively large crystallite sizes [1–4]. Continuous efforts have been made in the last few decades by several groups [5–7] to synthesize porous alumina with high surface area by high-temperature dehydration of bulk powders [8], modified sol-gel synthesis in the presence of organic moieties [9, 10], different surfactants [3], block copolymers [11–14], or evaporation-induced self-assembly (EISA) with colloidal precursors and amine structural agents [15, 16]. These materials represent an active support, which may participate positively or negatively in the formation of the final catalysts. Moreover, the methods of hard templating [17] (carbon template) and microwave irradiation [18] in the presence of surfactants have been applied to synthesize alumina materials with crystalline, ordered, and uniform mesopores. However, this process is very time consuming and hardly scalable for industrial applications. Ordered mesoporous materials
Ecopreneur Selection Using Fuzzy Similarity TOPSIS Variants  [PDF]
Shirin Noei, Arman Sargolzaei, Kang Yen, Saman Sargolzaei, Nansong Wu
American Journal of Industrial and Business Management (AJIBM) , 2017, DOI: 10.4236/ajibm.2017.77061
Abstract: A supply chain network coordinates flow of components from different suppliers to enhance a product that meets customers’ value expectations. Traditionally, companies consider price, quality, and lead time for selecting appropriate suppliers. Increasing environmental concerns, government regulations, and long-term profitability have forced companies to reduce pollution. In addition, in a complex business environment, supply managers should have flexibility skills to act entrepreneurially. Being ecopreneur is a paradigm modification from being a green supplier and entrepreneur toward global economy and sustainability. Although ecopreneur selection is a strategic key to project success, construction industry lacks a systematic approach for decision-making processes. When historical data are not available or adequate, subjective judgment of experts is the only source of information for decision. Fuzzy logic helps decision makers to translate qualitative terms into quantitative information, whereas TOPSIS method ranks alternatives according to their relative distance to the ideal solution. This paper aims to rank ecopreneurs according to the criteria for green entrepreneur selection. In this case, construction-related experts are interviewed to first rate the importance of each criterion as their point of view, and then rate performance of each candidate in accordance to the most important criteria for ecopreneur selection. The final response is expressed based on the average of new variants of fuzzy TOPSIS each using a different fuzzy similarity measure. A numerical example is also presented to illustrate the process in detail.
Changes of Proline Content and Activity of Antioxidative Enzymes in Two Canola Genotype under Drought Stress
Heshmat Omidi
American Journal of Plant Physiology , 2010,
Abstract: The aim of present study was to get further information on the ability of drought stress applied to retard senescence and to frustrate inhibitory effects of drought-stress via comparing two canola genotypes differing in drought tolerance. The objective of this work was to evaluate the effects of the drought stress (control, -0.5, -1 and -1.5 Mpa) on two canola genotypes (Okapi and RGS). The experiment was factorial with four replications at experimental greenhouse at Center of Agriculture Research-Shahed, Iran, during 2006-2007. Morphological parameters of root and shoot dry weight, proline content osmolyte and enzyme activities of Ascorbate peroxidase (APx), Guaiacol peroxidase (GAx) and Catalase (Cat) in shoot and root of tissues canola genotypes were highly significant differences for main and interaction effects of two factors (Drought (D) and Genotype (G)) studied. Drought decreased the roots and shoots dry weight of canola plants and this effect was particularly significant at high level of stress. So, results indicated that proline content, ascorbate peroxidase (APx) and Guaiacol peroxidase (GAx) and Catalase (Cat) activity in root and shoot increased with enhancement of drought stress in the two genotypes. Of course, the proline content and antioxidant activities in Okapi genotype were more than RGS genotype. These results showed that Okapi genotype tolerated drought stress than RGS with increasing of proline content and antioxidant activities including GAx and APx. Shoot always maintained higher level of free Catalase (CAT) contents than the root. Therefore, the evaluation of both antioxidant enzymes and proline content can be suggested for Mechanisms of drought stress tolerance.
Libraries Usage of On-line Electronic Information Resources
Heshmat Qassem
Cybrarians Journal , 2004,
Abstract:
Effect of Preheating Temperature on the Mechanical and Fracture Properties of Welded Pearlitic Rail Steels  [PDF]
Heshmat A. Aglan, Sudan Ahmed, Kaushal R. Prayakarao, Mahmood Fateh
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.511101
Abstract:

The effect of preheating temperature on the mechanical and fracture behavior, hardness, and the microstructure of slot welded pearlitic rail steel were studied. Railhead sections with slots were preheated to 200℃, 300℃, 350℃ and 400℃ before gas metal arc filling to simulate defects repair. Another sample, welded at room temperature (RT) with no preheat, was studied in comparison. The parent rail steel has ultimate strength, yield strength and strain to failure of 1146 MPa, 717 MPa and 9.3%, respectively. Optimum values of these properties for the welded rail steels were found to be 1023 MPa, 655 MPa and 4.7%, respectively, for the 200℃ preheat temperature. On this basis, the optimum weld efficiency was found to be 89.2%. The average apparent fracture toughness KI for the parent rail was 127 MPa.m0.5, while that for the optimum welded joint (200℃ preheat) was 116.5 MPa.m0.5. In addition, the average hardness values of the weld, fusion zone, and heat affected zone (HAZ) were 313.5, 332 and 313.6 HB, respectively, while that for parent rail steel was about 360 HB. Dominance of bainite and acicular ferrite phase in the weld microstructure was observed at 200℃ preheat.

Noise Removal in Speech Processing Using Spectral Subtraction  [PDF]
Marc Karam, Hasan F. Khazaal, Heshmat Aglan, Cliston Cole
Journal of Signal and Information Processing (JSIP) , 2014, DOI: 10.4236/jsip.2014.52006
Abstract:

Spectral subtraction is used in this research as a method to remove noise from noisy speech signals in the frequency domain. This method consists of computing the spectrum of the noisy speech using the Fast Fourier Transform (FFT) and subtracting the average magnitude of the noise spectrum from the noisy speech spectrum. We applied spectral subtraction to the speech signal “Real graph”. A digital audio recorder system embedded in a personal computer was used to sample the speech signal “Real graph” to which we digitally added vacuum cleaner noise. The noise removal algorithm was implemented using Matlab software by storing the noisy speech data into Hanning time-widowed half-overlapped data buffers, computing the corresponding spectrums using the FFT, removing the noise from the noisy speech, and reconstructing the speech back into the time domain using the inverse Fast Fourier Transform (IFFT). The performance of the algorithm was evaluated by calculating the Speech to Noise Ratio (SNR). Frame averaging was introduced as an optional technique that could improve the SNR. Seventeen different configurations with various lengths of the Hanning time windows, various degrees of data buffers overlapping, and various numbers of frames to be averaged were investigated in view of improving the SNR. Results showed that using one-fourth overlapped data buffers with 128 points Hanning windows and no frames averaging leads to the best performance in removing noise from the noisy speech.

Fractional-Order Control of a Nonlinear Time-Delay System: Case Study in Oxygen Regulation in the Heart-Lung Machine
S. J. Sadati,A. Ranjbar Noei,R. Ghaderi
Journal of Control Science and Engineering , 2012, DOI: 10.1155/2012/478346
Abstract: A fractional-order controller will be proposed to regulate the inlet oxygen into the heart-lung machine. An analytical approach will be explained to satisfy some requirements together with practical implementation of some restrictions for the first time. Primarily a nonlinear single-input single-output (SISO) time-delay model which was obtained previously in the literature is introduced for the oxygen generation process in the heart-lung machine system and we will complete it by adding some new states to control it. Thereafter, the system is linearized using the state feedback linearization approach to find a third-order time-delay dynamics. Consequently classical PID and fractional order controllers are gained to assess the quality of the proposed technique. A set of optimal parameters of those controllers are achieved through the genetic algorithm optimization procedure through minimizing a cost function. Our design method focuses on minimizing some famous performance criterions such as IAE, ISE, and ITSE. In the genetic algorithm, the controller parameters are chosen as a random population. The best relevant values are achieved by reducing the cost function. A time-domain simulation signifies the performance of controller with respect to a traditional optimized PID controller.
Assessment of He's homotopy perturbation method for optimal control of linear time-delay systems
A. Sargolzaei,K. K. Yen,S. Noei,H. Ramezanpour
Applied Mathematical Sciences , 2013,
Abstract: This paper renders an optimal regulator for a system with state time-delayand quadratic performance index. First, by means of Maximum Principle andnecessary optimal conditions, a continues-time two-point boundary-value problem(TPBVP) including both time-delay and time-advance is derived. Then, usingHomotopy Perturbation Method (HPM), the obtained TPBVP is transformed intoa sequence of linear time-invariant TPBVP without any time-delay or timeadvance.Solving the resulted linear TPBVP sequence in a recursive manner,concludes that the optimal control law in the form of rapid convergent series. Atthe end, an iterative algorithm with low complexity in computation and fastconvergence rate is proposed to achieve an accurate enough suboptimal controllaw. It's worth noting that simulation based on application of a harmonicoscillator is conducted to demonstrate efficiency of this method.
A Modal Series Representation of Genesio Chaotic System
H. Ramezanpour,B. Razeghi,G. Darmani,S. Noei,A. Sargolzaei
Physics , 2012, DOI: 10.5121/ijics.2012.2301
Abstract: In this paper an analytic approach is devised to represent, and study the behavior of, nonlinear dynamic chaotic Genesio system using general nonlinear modal representation. In this approach, the original nonlinear ordinary differential equations (ODEs) of model transforms to a sequence of linear time- invariant ODEs. By solving the proposed linear ODEs sequence, the exact solution of the original nonlinear problem is determined in terms of uniformly convergent series. Also an efficient algorithm with low computational complexity and high accuracy is presented to find the approximate solution. Simulation results indicate the effectiveness of the proposed method.
Serum inhibin levels in polycystic ovary syndrome: a case control study
M. Lankarani,N. Valizadeh,R. Heshmat
Tehran University Medical Journal , 2006,
Abstract: Background: Polycystic ovary syndrome(PCOS) is the most common endocrinopathy in women and the most common causes of anovulatory infertility.Inadequate follicule stimulating hormone is hypothesized to be a proximate cause of anovulation.Inhibins are glycoprotein hormone produced by the granulosa and theca cells of the ovary that selectivly inhibits FSH production and or release from the pituitary. The possible role of inhibin in the etiology of polycystic ovary syndrome (PCOS) is controversial. This study was designed to investigate levels of serum inhibin in women with PCOS. Methods: In a case-control setting 41 women with PCOS from the endocrine and gynecology and obstetrics clinic of Shariati Hospital and 44 women with normal cycles (control group) aged 15-40 year-old were evaluated. In all patients with PCOS and control women appropriate medical history was taken and physical examination was done.Serum inhibin levels were compared in two groups. Statistical analysis was performed using the Mann -Whitney U test Results: Mean age of cases and controls was 23.6±5.3 and 23.1 ±3.9 years, respectively. Mean body mass index (BMI) in cases and controls were 25.07±5.45 and 21.33± 2.46 Kg/m2, respectively. There was no statistically significant difference in mean age between the two groups (p > 0.05) but mean BMI was significantly different between the two groups (p < 0.001). Mean serum levels of inhibin in cases and controls were 1.62±1.23 and 2.26±2.26 U/ml, respectively which was not significantly different between the two groups (p: 0.168). Conclusion: There was no significant difference in serum inhibin levels between patients with PCOS and healthy women. We concluded that basal inhibin levels cannot be used for routine screening in women with PCOS. Further study is needed to determine the role of inhibin in these patients with assay of its two subunits (Inhibin A and B).
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