Synthesis and characterization of alumina supported sub-nanoporous SiO2–10 wt%TiO2 membrane for nitrogen separation

Yaghoob Farhang-Ghoje Biglu,Ehsan Taheri-Nassaj 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.5

Membrane of SiO2–10TiO2 was produced by dip coating on mesoporous-titania-coated macroporous alumina support. The amorphous SiO2–10TiO2 top layer with thickness of 0.9 mm was obtained as a homogenous and defect free surface. Gas permeation tests show a decrease in permeation in order of CH4 > N2 for the support, and N2 > CH4 for the multilayer membrane. The membrane delivering promised single gas separation factor for N2/CH4 (1.75). It was also observed that the membrane separation factor in binary gas mixture was 12–15% of the single gas separation factor, while the permeation revealed a decrease in gas mixture.

Performance of concrete structures with a combination of normal SCC and fiber SCC

Kianoosh Farhang,Hamoon Fathi 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.20 No.6

Fiber reinforced concretes exhibit higher tensile strength depending on the percent and type of the fiber used. These concretes are used to reduce cracks and improve concrete behavior. The use of these fibers increases the production costs and reduces the compressive strength to a certain extent. Therefore, the use of fiber reinforced concrete in regions where higher tensile strength is required can cut costs and improve the overall structural strength. The behavior of fiber reinforced concrete and normal concrete adjacent to each other was investigated in the present study. The concrete used was self-compacting and did not require vibration. The samples had 0, 1, 2 and 4 wt% polypropylene fibers. 15 cm sample cubes were subjected to uniaxial loads to investigate their compressive strength. Fiber Self-Compacting Concrete was poured in the mold up to 0, 30, 50, 70 and 100 percent of the mold height, and then Self-Compacting Concrete without fiber was added to the empty section of that mold. In order to investigate concrete behavior under bending moment, concrete beam samples with similar conditions were prepared and subjected to the three-point bending flexural test. The results revealed that normal Self-Compacting Concrete and Fiber Self-Compacting Concrete may be used in adjacent to each other in structures and structural members. Moreover, no separation was observed at the interface of Fiber Self-Compacting Concrete and Self-Compacting Concrete, either in the cubic samples under compression or in the concrete beams under bending moment.

The dark side of surge pricing and the mitigating role of information disclosure

Bhattarai Ashok,Farhang Maryam,Adjei Mavis T.,Saavedra Torres Jose L.,Zaad Ash 한국마케팅과학회 2023 마케팅과학연구 Vol.33 No.4

This research paper investigates the impact of surge pricing, a dynamic pricing strategy that adjusts prices based on real-time demand and supply, on customers’ perception of price fairness. We aim to provide insights for both academic and managerial audiences. Our study focuses on how businesses using surge pricing can minimize negative effects on customer behavior by properly communicating price changes. We conducted two experiments to examine customers’ fairness perception of surge pricing policies. Our findings revealed that customers generally perceive surge pricing as less fair. However, we also discovered that aligning the amount of information shared with the price increase can effectively improve these fairness perceptions. Our research contributes to the literature on price communication by exploring factors that influence consumers’ understanding and acceptance of price changes. Additionally, our findings offer practical guidance for businesses on how to communicate pricing information in a way that customers perceive as fair, ultimately benefiting both companies and their customers.

Parathyroid Hormone and 25-Hydroxyvitamin D Do Not Mediate the Association between Dietary Calcium, Protein and Vitamin D Intake and Adiposity and Lipid Profile in Patients with Type 2 Diabetes: a Structural Equation Modeling Approach

( Parisa Janmohammadi ),( Farhang Djafari ),( Gholamreza Mohammadi Farsani ),( Sakineh Shab-bidar ),( Ali Asghar Haeri Mehrizi ) 한국임상영양학회 2020 Clinical Nutrition Research Vol.9 No.4

This study aimed to utilize structural equation modeling (SEM) techniques to determine the effects of dietary calcium, protein and vitamin D on adiposity and lipidemia and to assess mediatory effects of parathyroid hormone (PTH) and 25-hydroxyvitamin D (25(OH)D) in patients with type 2 diabetes. In this cross-sectional study, a total of 150 diabetic patients (93 females and 57 males) were randomly selected. Anthropometric measures, biochemical analyses, and fat mass percent were recorded. Nutritional data were collected. SEM was performed. Based on the primary hypothesis, adiposity and lipidemia were fitted in a model. The direct effects of dietary calcium (λ = -0.165, p value = 0.002) and PTH (λ = -0.143, p value = 0.011) were significantly associated with lipidemia. There were no significant effects for dietary protein on PTH (λ = -0.270, p value = 0.057), 25(OH)D (λ = -0.071, p value = 0.613), lipidemia (λ = -0.044; p value = 0.638) or adiposity (λ = -0.009, p value = 0.949) as well as for dietary vitamin D on PTH (λ = -0.119, p value = 0.194), 25(OH)D (λ = 0.023, p value = 0.806), lipidemia (λ = 0.034, p value = 0.587) or adiposity (λ = -0.221, p value = 0.118). The correlation between calcium intake and lipidemia, and adiposity are not mediated by 25(OH)D and PTH. There were the direct effects of dietary calcium on adiposity in patients with type 2 diabetes. The model can be tested in future longitudinal and intervention studies to identify the predictors of obesity.

Technological Change and Contribution to Growth and Convergence

Edward Nissan,Farhang Niroomand 중앙대학교 경제연구소 2006 Journal of Economic Development Vol.31 No.1

This paper incorporates data on efficiency and output per worker for 1965 and 1990 for 57 countries divided into four groups to seek an understanding of similarities and differences among them. Tools employed were testing for equality of means and testing for convergence. The findings indicate that the gaps between the groups were widened during the period studied for both efficiency and output per worker. While divergence was observed when all countries were grouped in one set, there were indications of convergence when the groups were treated separately.

An evolutionary yield function based on Barlat 2000 yield function for the superconducting niobium sheet

Payam Darbandi,Farhang Pourboghrat 한국소성가공학회 2011 기타자료 Vol.2011 No.8

Superconducting radio frequency (SRF) niobium cavities are widely used in high-energy physics to accelerate particle beams in particle accelerators. The performance of SRF cavities is affected by the microstructure and purity of the niobium sheet, surface quality, geometry, etc. Following optimum strain paths in the forming of these cavities can significantly control these parameters. To select these strain paths, however, information about the mechanical behavior, microstructure, and formability of the niobium sheet is required. In this study the Barlat 2000 yield function has been used as a yield function for high purity niobium. Results from this study showed that, due to intrinsic behavior, it is necessary to evolve the anisotropic coefficients of Barlat’s yield function in order to properly model the plastic behavior of the niobium sheet. The accuracy of the newly developed evolutionary yield function was verified by applying it to the modeling of the hydrostatic bulging of the niobium sheet. Also, in a separate attempt crystal plasticity finite element method was use to model the behavior of the polycrystalline niobium sheet with a particular initial texture.

Antifungal Effect of Plant Essential Oils on Controlling Phytophthora Species

Amini, Jahanshir,Farhang, Vahid,Javadi, Taimoor,Nazemi, Javad The Korean Society of Plant Pathology 2016 Plant Pathology Journal Vol.32 No.1

In this study, antifungal activity of essential oils of Cymbopogon citratus and Ocimum basilicum and two fungicides Mancozeb and Metalaxyl-Mancozeb in six different concentrations were investigated for controlling three species of Phytophthora, including P. capsici, P. drechsleri and P. melonis on pepper, cucumber and melon under in vitro and greenhouse conditions, respectively. Under the in vitro condition, the median effective concen- tration ($EC_{50}$) values (ppm) of plant essential oils and fungicides were measured. In greenhouse, soil infested with Phytophthora species was treated by adding 50 ml of essential oils and fungicides (100 ppm). Disease severity was determined after 28 days. Among two tested plant essential oils, C. citratus had the lowest $EC_{50}$ values for inhibition of the mycelial growth of P. capsici (31.473), P. melonis (33.097) and P. drechsleri (69.112), respectively. The mean $EC_{50}$ values for Metalaxyl-Mancozeb on these pathogens were 20.87, 20.06 and 17.70, respectively. Chemical analysis of plant essential oils by GC-MS showed that, among 42 compounds identified from C. citratus, two compounds ${\beta}$-geranial (${\alpha}$-citral) (39.16%) and z-citral (30.95%) were the most abundant. Under the greenhouse condition, Metalaxyl-Mancozeb caused the greatest reduction in disease severity, 84.2%, 86.8% and 92.1% on melon, cucumber, and pepper, respectively. The C. citratus essential oil reduced disease severity from 47.4% to 60.5% compared to the untreated control ($p{\leq}0.05$). Essential oils of O. basilicum had the lowest effects on the pathogens under in vitro and greenhouse conditions. These results show that essential oils may contribute to the development of new antifungal agents to protect the crops from Phytophthora diseases.

Finite element modeling of laser ultrasonics nondestructive evaluation technique in ablation regime

Salman Shamsaei,Farhang Honarvar Techno-Press 2023 Advances in computational design Vol.8 No.3

In this paper, finite element modeling of the laser ultrasonics (LU) process in ablation regime is of interest. The momentum resulting from the removal of material from the specimen surface by the laser beam radiation in ablation regime is modeled as a pressure pulse. To model this pressure pulse, two equations are required: one for the spatial distribution and one for the temporal distribution of the pulse. Previous researchers have proposed various equations for the spatial and temporal distributions of the pressure pulse in different laser applications. All available equations are examined and the best combination of the temporal and spatial distributions of the pressure pulse that provides the most accurate results is identified. This combination of temporal and spatial distributions has never been used for modeling laser ultrasonics before. Then by using this new model, the effects of variations in pulse duration and laser spot radius on the shape, amplitude, and frequency spectrum of ultrasonic waves are studied. Furthermore, the LU in thermoelastic regime is simulated by this model and compared with LU in ablation regime. The interaction of ultrasonic waves with a defect is also investigated in the LU process in ablation regime. Good agreement of the results obtained from the new finite element model and available experimental data confirms the accuracy of the proposed model.

비직교이방성 조성방정식을 이용한 직물강화 열가소성 복합재료의 액압성형공정 해석

유웅렬,정관수,강태진,Pourboghrat Farhang 한국섬유공학회 2002 한국섬유공학회지 Vol.39 No.4

A new constitutive model has been developed based on the homogenization method considering the micrcostructures of composites including both the mechanical and structural properties of fabric reinforcements. In particular, the current model aims to account for the effect of the fiber stiffness difference and orientation on anisotropy and also to simulate shear deformation without significant length change, as common in FRT(fabric reinforced thermoplastics) composite forming. For validation purposes, the model was implemented in an explicit dynamic finite element ocde and tested for pure shear. Using the new constitutive equation, the deformation behavior of woven fabric reinforced thermoplastic composites in hydroforming process was also analyzed.

Titanium Acetylacetonate as an Excellent Ion-Carrier inConstruction of Iodide Sensor

MohammadRezaGanjali,Azadeh Daftari,Farhang Mizani,Masoud Salavati-Niasari 대한화학회 2003 Bulletin of the Korean Chemical Society Vol.24 No.1