Valorization of waste cooking oil based biodiesel for biolubricant production in a vertical pulsed column: Energy efficient process approach

International audienceDevelopment of bio-based lubricants have received growing interest as sustainable substitutes to petroleum-based lubricants due to their renewability, biodegradability and superior physicochemical properties. Biolubricant production from waste cooking oil in an intensified reactor, which is designed with the aim of scaling-up for industrial purposes, can effectively decrease the cost of finished product. In this study, a vertical pulsed column with tri-orifice baffles was applied to produce trimethylolpropane fatty acid triester (biolubricant) from waste cooking oil, which is a cost and environmentally effective feedstock. This type of reactor enables high interfacial areas between immiscible reactants, leading to improved reaction performance. In addition, response surface methodology was used to optimize the levels of different operating parameters to obtain the highest reaction yield and the lowest power consumption. An optimal reaction yield of 83.3% and power consumption of 1006 kW/m 3 were obtained with an oscillation frequency of 3.6 Hz, a baffle spacing of 1.45d e , a molar ratio of 4:1 and a potassium carbonate catalyst loading of 1%

Shape optimization of microvascular composites used in active cooling applications

Inspired by microchannels networks in biological systems, microvascular composites are being used for various applications including active cooling, autonomic healing, and sensing. The recent development of a manufacturing technique for microvascular composites based on a sacrificial fiber approach has enabled the creation of complex networks of microchannels embedded in composite parts [1]. Motivated by these recent improvements in manufacturing of microvascular composites, we study design of an actively cooled composite plate. We examine the impact of microchannels configuration on the thermal response of the microvascular composite. Here, the composite plate is subjected to a heat flux that causes a high surface temperature in the absence of the active cooling by microchannels. The objective of this study is to determine the optimal configuration of the microchannels to maximize the thermal efficiency of microchannels to keep the domain temperature below a critical temperature value. We present a new gradient-based Isogeometric Interface-enriched Generalized Finite Element Method (IIGFEM) [2–4] optimization scheme that allows for the accurate and efficient extraction of the sensitivity of objective functions and constraints on the design parameters that define the geometry of the microchannels. At the heart of the modeling effort, the IIGFEM allows for the very accurate and efficient capture of the thermal impact of the embedded microchannel network on the thermal field in the composite part. Because the microchannels diameters are typically much smaller than other characteristic dimensions of the problem, we model microchannels as line (or curve) sinks. The IIGFEM solver allows for the capture of curved and branched microchannels over a mesh that does not conform to the geometry of the microchannels. One of the key challenges associated with the conventional finite element-based shape optimization of microvascular composites is the large mesh distortion that often takes place during the optimization process, as the finite element mesh must conform to the evolving microstructural elements. This mesh distortion may affect the accuracy of the optimum solution. Because of the stationary nature of the nonconforming mesh used by the IIGFEM, the issue of mesh distortion disappears. In this study, we adopt an isogeometric IGFEM-based adjoint shape sensitivity approach, which is simplified by the fact that only the enrichment (interface) nodes move, appear or disappear during the shape optimization process. To demonstrate the performance of the method, a set of microstructural shape optimization problems for the design of microvascular composites are presented

Simulation of the microlevel damage evolution in polymer matrix composites

A 3D Isogeometric Interface-Enriched Generalized Finite Element Method (IIGFEM) is developed to analyze problems with complex, discontinuous gradient fields commonly observed in the structural analysis of heterogeneous materials including polymer matrix composites [1]. In the proposed approach, the mesh generation process is significantly simplified by utilizing simple structured meshes that do not conform to the complex microstructure of the heterogeneous media. Non-Uniform Rational B-Splines, commonly used in computer-aided design, are adopted in the IIGFEM to augment the finite element approximation space and capture the weak discontinuity present along material interfaces. The IIGFEM offers many advantages, such as the simplicity and accuracy of numerical integration, the straightforward implementation of essential boundary conditions, and the flexibility in the choice of the local solution refinement The ability to model complex material interfaces and the mesh independence are two of key features of the IIGFEM that enable it to tackle problems with evolving material response, such as computational study of damage in solids. Here, we utilize the IIGFEM scheme to study the impact of microstructural details on the initiation and evolution of the damage in polymer matrix composites. For this purpose, in this study, we incorporate a three-parameter isotropic damage model [2] into our IIGFEM solver to capture the fracture response of the matrix in a unidirectional composite layer. To bypass numerical issues associated with mesh bias, we use a viscous regularization scheme proposed by Simo and Ju [3]. The numerical stability of the proposed approach is studied and its advantages and limitations are discussed in detail. Finally, a number of numerical examples are presented to demonstrate the effect of RVE size and filler volume fraction on the damage behavior of fiber-reinforced polymer matrix composites. REFERENCES [1] Safdari, M., Najafi, A.R., Sottos, N.R., Geubelle, P.H. An Isogeometric Interface-Enriched Generalized Finite Element Method (IGFEM) for problems with complex discontinuous gradient field. Submitted (2014). [2] Matous, K., Kulkarni, M.G., Geubelle, P.H. Multiscale cohesive failure modeling of heterogeneous adhesives. Journal of the Mechanics and Physics of Solids. 2008, 56, 1511–1533. [3] Simo, J.C., Ju, J.W. Strain- and stress-based continuum damage models—ii. computational aspects. International Journal of Solids and Structures. 1987, 23(7), 841–869

A NURBS-based interface-enriched generalized finite element scheme for the computational analysis and design of high temperature microvascular composites

Computational studies on multifunctional microvascular composite materials for high temperature application have focused on simple microchannel geometries [1–2]. Motivated by recent advances in the manufacturing of microvascular composites based on a sacrificial fiber technique that allows a complex network of curved microchannels to be embedded in the material [3], we develop an Interface Enriched Generalized Finite Element Method (IGFEM) [4] with Non-Uniform Rational B-Splines (NURBS) to analyze the impact of the microchannel network on the thermal field in the composite component [5]. By capturing the gradient discontinuity present at the microchannels, the method is able to simulate efficiently and accurately the thermal response of the microvascular composite without the need for a mesh that conforms to the geometry of the microchannels. We show that near-optimal convergence rate can be achieved and that IGFEM is more accurate than standard finite element method for coarse meshes when the enrichment functions are constructed using the NURBS description of the curved microchannels. Verification studies conducted against a detailed multiphysics model based on the Navier–Stokes equation for the fluid shows that the much simpler line source/sink model is very accurate for problems involving microvascular plates and fins. Various application problems are presented to demonstrate the efficiency, flexibility and accuracy of the proposed method. REFERENCES [1] Soghrati, S., Thakre, P.R., White, S.R., Sottos, N.R., Geubelle, P.H. Computational modeling and design of actively-cooled microvascular materials. Int. J. Heat Mass Transfer. 2012, 55, 5309–5321 [2] Soghrati, S., Najafi, A.R., Hughes, K.M., Lin, J.H., White, S.R., Sottos, N.R., Geubelle, P.H. Computational analysis of actively-cooled 3D woven microvascular composites using a stabilized interface-enriched generalized finite element method. Int. J. Heat Mass Transfer. 2013, 65, 153–164. [3] Esser-Kahn, A.P., Thakre, P.R., Dong, H., Patrick, J.F., Vlasko-Vlasov, V.K., Sottos, N.R., Moore, J.S., White, S.R. Three-dimensional microvascular fiber-reinforced composites. Advanced Materials. 2011, 23, 3654–3658. [4] Soghrati, S., Aragón, A.M., Duarte, C.A., Geubelle, P.H. An interface-enriched generalized FEM for problems with discontinuous gradient fields. Int. J. Numer. Methods Eng. 2012, 89, 991–1008. [5] Tan, M.H.Y., Safdari, M., Najafi, A.R., Geubelle, P.H. A NURBS-based interface-enriched generalized finite element scheme for the thermal analysis and design of microvascular composites. 2014 (submitted)

TOPSIS multi-criteria decision modeling approach for biolubricant selection for two-stroke petrol engines

Exhaust pollutants from two-stroke petrol engines are a problem for the environment. Biolubricants are a new generation of renewable and eco-friendly vegetable-based lubricants, which have attracted a lot of attention in recent years. In this paper, the applicability of the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method to support the process of building the scoring system for selecting an appropriate two-stroke lubricant has been analyzed. For this purpose, biolubricants (TMP-triesters) based on castor oil, palm oil, and waste cooking oil were produced and then utilized in a 200 cc two-stroke gasoline engine to investigate their effects on its performance and exhaust emissions. The results obtained from the use of the entropy technique in the TOPSIS algorithm showed that palm oil-based lubricant took up the greatest distance from the Negative Ideal Solution (NIS) and was selected as the most optimal lubricant for these types of engines

Energy management of virtual power plant considering distributed generation sizing and pricing

UID/EMS/00667/2019The energy management of virtual power plants faces some fundamental challenges that make it complicated compared to conventional power plants, such as uncertainty in production, consumption, energy price, and availability of network components. Continuous monitoring and scaling of network gain status, using smart grids provides valuable instantaneous information about network conditions such as production, consumption, power lines, and network availability. Therefore, by creating a bidirectional communication between the energy management system and the grid users such as producers or energy applicants, it will afford a suitable platform to develop more efficient vector of the virtual power plant. The paper is treated with optimal sizing of DG units and the price of their electricity sales to achieve security issues and other technical considerations in the system. The ultimate goal in this study to determine the active demand power required to increase system loading capability and to withstand disturbances. The effect of different types of DG units in simulations is considered and then the efficiency of each equipment such as converters, wind turbines, electrolyzers, etc., is achieved to minimize the total operation cost and losses, improve voltage profiles, and address other security issues and reliability. The simulations are done in three cases and compared with HOMER software to validate the ability of proposed model.publishersversionpublishe

Challenges of implementing family-based dignity intervention

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Evaluating the protective effect of resveratrol, Q10, and alpha-lipoic acid on radiation-induced mice spermatogenesis injury: A histopathological study

Background: Testis is one of the most sensitive organs against the toxic effect of ionizing radiation. Exposure to even a low dose of radiation during radiotherapy, diagnostic radiology, or a radiological event could pose a threat to spermatogenesis. This may lead to temporary or permanent infertility or even transfer of genomic instability to the next generations. Objective: In this study, we evaluated the protective effect of treatment with three natural antioxidants; resveratrol, alpha lipoic acid, and coenzyme Q10 on radiation-induced spermatogenesis injury. Materials and Methods: 30 NMRI mice (6-8 wk, 30 ± 5 gr) were randomly divided into six groups (n=5/each) as 1) control; 2) radiation; 3) radiation + resveratrol; 4) radiation + alpha lipoic acid; 5) radiation + resveratrol + alpha lipoic acid; and 6) radiation+ Q10. Mice were treated with 100 mg/kg resveratrol or 200 mg/kg alpha lipoic acid or a combination of these drugs. Also, Q10 was administered at 200 mg/kg. All treatments were performed daily from two days before to 30 min before irradiation. Afterward, mice were exposed to 2 Gy 60Co gamma rays; 37 days after irradiation, the testicular samples were collected and evaluated for histopathological parameters. Results: Results showed that these agents are able to alleviate some toxicological parameters such as basal lamina and epididymis decreased sperm density. Also, all agents were able to increase Johnsen score. However, they could not protect against radiation-induced edema, atrophy of seminiferous tubules, and hyperplasia in Leydig cells. Conclusion: This study indicates that resveratrol, alpha-lipoic acid, and Q10 have the potential to reduce some of the side effects of radiation on mice spermatogenesis. However, they cannot protect Leydig cells as a source of testosterone and seminiferous tubules as the location of sperm maturation. Key words: Radiation, Spermatogenesis, Resveratrol, Alpha-Lipoic Acid, Coenzyme Q10

Determination of fecal Alpha 1-Antitrypsin as marker for differentiation of microbial and non-microbial diarrhea

Alpha-1 anti-trypsin=AAT) یکی از پروتئین های فاز حاد سرم انسان است که سطوح سرمی آن در بعضی از بیماری ها از جمله بیماری های کبدی، کلیوی و ریوی تغییر می یابد و متعاقب اختلالات گوارشی از جمله اسهال، AAT از طریق مدفوع دفع می شود. اندازه گیری AAT مدفوع در تشخیص دفع غیر طبیعی پروتئین مورد استفاده قرار گرفته است. در مطالعات مختلفی، میزان AAT مدفوع به عنوان شاخص در تشخیص افتراقی انواع اختلالت گوارشی اندازه گیری شده است. باتوجه به اینکه تشخیص افتراقی اسهال های میکروبی از غیر میکروبی به علت نیاز به انجام کشت مدفوع وقت گیر می باشد لذا در این مطالعه سنجش میزان AAT مدفوع به عنوان یک آزمایش غربالی اولیه برای متمایز نمودن انواع اسهال ها (عفونی باکتریال و غیر عفونی) مورد مطالعه قرار گرفته است. در این مطالعه مورد-شاهدی مقدار AAT مدفوع کودکان بستری شده در بخش اطفال بیمارستان هاجر شهرکرد اندازه گیری شد. گروه اول شامل 30 کودک مبتلا به اسهال بودند که نتیجه کشت مدفوع آنها از نظر میکروبی مثبت و گروه دوم شامل 30 کودک مبتلا به اسهال بودند که نتیجه کشت مدفوع آنها از نظر میکروبی منفی بوده است و گروه شاهد شامل 30 کودک غیر مبتلا به اسهال بود. در تمام کودکان فوق میزان AAT مدفوع به روش رادیال ایمونودیفیوژن اندازه گیری گردید. میانگین مقدار AAT در گروه اول mg/dl 46.2±50، در گروه دوم mg/dl 34.77±25 و در گروه شاهد (افراد سالم) mg/dl 3.35±1.08 می باشد. از نظر آماری میانگین AAT در سه گروه اختلاف معنی داری نشان داد. نتایج این بررسی نشان داد که میانگین مقدار AAT در گروه مبتلا به اسهال و دارای کشت میکروبی مثبت (گروه اول) بالاتر از سایر گروه ها بوده است. اما در سطح انفرادی تمام افراد این گروه میزان AAT بالایی نداشتند. لذا پیشنهاد می گردد در مطالعه تکمیلی میزان AAT مدفوع در مقایسه با میزان AAT سرم اندازه گیری گردد

Development of a Procedure for Risk-Based Qualification of Additively Manufactured ‎Components: Adopting to Oil and Gas Industrial Applications

Recent advances in additive manufacturing (AM) technology provide the potential for on-demand and rapid production of spare parts during urgent repair times. Recently, big oil and gas companies have shown early progress in using additive technology in manufacturing specific heat exchangers, downhole cleanout tool nozzles, offshore risers, gas turbine nozzles, and subsea chemical stick injection tools. Despite the mentioned progress, the current adoption level of additive technology for the offshore oil and gas industry is very limited. Non-destructive and destructive evaluation methods of additively manufactured metallic components have been studied extensively. However, the technique selection procedure and scope of the required test methods have not been studied sufficiently. This paper discusses various elements related to the qualification of additively manufactured components for application in the oil and gas industry. A risk-based qualification method for identifying the scopes of required non-destructive and destructive tests and the resulting qualification procedure for additively manufactured spare components in offshore oil and gas applications is suggested.Development of a Procedure for Risk-Based Qualification of Additively Manufactured ‎Components: Adopting to Oil and Gas Industrial ApplicationspublishedVersio