Inverse Identification of Thermal Properties of Charring Ablators

The modified Levenberg-Marquardt method is used for simultaneous estimation of decomposition kinetic coefficients and temperature-dependent thermophysical properties of charring ablators with a moving boundary over a wide temperature range. No prior information is used for the functional forms of the unknown thermal conductivity and specific heat. The procedure used differs from the traditional one in that it does not require prescribed time-dependent surface heat flux, recession rate, and pyrolysis gas mass flow rate. These time-dependent quantities may recover during an iterative procedure. The measured temperatures are simulated numerically by the Charring material ablation code, which accounts for unsteady ablation. The method can determine unknown parameters in an efficient manner with reasonable accuracy, without exact advance knowledge about the net surface heat flux, surface recession, and gas flux through the material.     

Zinc Oxide/Graphene Oxide as a Robust Active Catalyst for Direct Oxidative Synthesis of Nitriles from Alcohols in Water

Catalysis Letters - In this work, without using any linker or chemical modification of graphene oxide, a zinc oxide immobilized graphene oxide-based catalyst was used for the direct aerobic...     

Synthesis of biocompatible and degradable microspheres based on 2‐hydroxyethyl methacrylate via microfluidic method

Monodisperse poly(2‐hydroxyethyl methacrylate), p‐HEMA, microspheres in size ranging from 16 to 340 (μm) were synthesized by in situ emulsion photopolymerization of HEMA monomer with polyethylene glycol diacrylate (p‐EGDA) by means of a three‐dimensional microfluidic flow‐focusing device. An aqueous solution of HEMA, p‐EGDA as chain extender and UV‐photoinitiator serving as dispersed phase formed microdroplets in a continuous oil phase mainly consisting of n‐heptane. A downward coaxial orifices design in the device led to confinement of the reaction admixtures thread to central axis of the microchannels. This design strategy could solve the wetting problem of dispersed phase with the microchannels leading to a successful production of monodisperse microspheres with size variation of less than 4%. The effects of concentration of p‐EGDA, surfactant, and flow rate ratios on microsphere size were examined. It was observed that increasing the concentration of p‐EGDA slightly increases the size whereas increasing the flow rate ratios of continuous to dispersed phase effectively decreases the size of microspheres. The rapid continuous synthesis of p‐HEMA based microspheres via the microfluidic route with reliable control over size, size distribution, and composition opens new doors for mass production of biocompatible and degradable polymeric microspheres for enormous biotechnological applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40925.     

A comparison of Zayandehrood River water values for agriculture and the environment

River water management is challenging not only since they are open systems with changing physical structures, but also because the water values are mostly unknown over varied sectors. If policymakers grasp water values, water management will be more efficient. This research intends to examine the values of water in agriculture, which receives the most substantial portion of water resources, with the values of water in the environment in Isfahan located in the Zayandehrood River basin of Iran. The consequences of contingent valuation and production function methods revealed that per cubic metre value of water is 13 times higher in the environment than agriculture. The government should reconsider the higher value of the environment despite it is a non‐market value. The contingent valuation model additionally proved that women exhibited 21% more willingness to pay than men in order to protect the environment; however, they are paid less by 36%.     

Synergetic effects of Y-zeolite and amorphous silica-alumina as main FCC catalyst components on triisopropylbenzene cracking and coke formation

The synergetic effects of HY-zeolite and silica-alumina (SA), as two major components of an FCC catalyst, on the cracking activity and coking tendency during catalytic cracking of 1,3,5-triisopropylbenzene (TiPB, as a resid representative) were studied. NaY-zeolite and SA were synthesized by hydrothermal and co-precipitation methods, respectively, and ammonium exchanged for three times at 80 °C. The catalysts were characterized by XRD, XRF, SEM, BET, AAS and ammonia TPD techniques. TiPB cracking was investigated on four different catalyst configurations including SA, Y-zeolite, SA.Y and SA-Y in a fixed bed reactor. SA.Y stands for physical mixture of equal amounts of Y-zeolite and SA. For SA-Y, a bed of SA was placed upstream of the same amount of Y-zeolite. The catalysts were in-situ activated at 475 °C and evaluated by TiPB cracking at 350 °C. The coke content of the catalyst beds, after 40 min cracking of TiPB, was estimated by TPO using an FT-IR gas cell. At 3 min time on stream, 5.2 times higher yield of benzene, as a deep cracking product, is observed on SA-Y as compared to SA.Y. The TiPB conversion decreases in the order of SA-Y > SA.Y > Y-zeolite ? SA. Furthermore, as compared to Y-zeolite, 24% lower coke is formed on SA-Y. Also CO evolution during TPO of coked SA-Y catalyst is about 24% lower than that of the coked zeolite. As a result, protecting of Y-zeolite by SA from direct exposure to resid feed enhances the cracking activity, decreases the tendency to coke formation and diminishes CO emission in the catalyst regeneration process.     

Friction compensation of double inverted pendulum on a cart using locally linear neuro-fuzzy model

Double inverted pendulum on a cart (DIPC) is a highly nonlinear system. Due to its complex dynamics, it is widely used as a test-bed plant for the verification of newly designed controllers. In DIPC, two pendulums are kept upward by linear movements of cart. Because of this linear motions and frequent switching of velocity directions, another nonlinearity caused by friction becomes dominant around the equilibrium point. Friction introduces limit cycles to the system and results in a poor steady-state response. To eliminate these negative effects, the locally linear neuro-fuzzy (LLNF) approach is used to build an inverse model for friction compensation. This model is compared with multilayer perceptron network in order to demonstrate the better performance of LLNF. To stabilize DIPC, a common optimal controller is used, and despite its limited performance, experimental results show that the application of inverse modeling for friction compensation improves the steady-state response outstandingly.     

A novel adaptive fuzzy predictive control for hybrid systems with mixed inputs

This paper proposes a new adaptive nonlinear model predictive control (NMPC) methodology for a class of hybrid systems with mixed inputs. For this purpose, an online fuzzy identification approach is presented to recursively estimate an evolving Takagi–Sugeno (eTS) model for the hybrid systems based on a potential clustering scheme. A receding horizon adaptive NMPC is then devised on the basis of the online identified eTS fuzzy model. The nonlinear MPC optimization problem is solved by a genetic algorithm (GA). Diverse sets of test scenarios have been conducted to comparatively demonstrate the robust performance of the proposed adaptive NMPC methodology on the challenging start-up operation of a hybrid continuous stirred tank reactor (CSTR) benchmark problem.     

Antimicrobial Property,Antioxidant Capacity,and Cytotoxicity of Essential Oil from Cumin Produced in Iran

ABSTRACT: Cumin (Cuminum cyminum) is one of the commonly used spices in food preparations. It is also used in traditional medicine as a stimulant, a carminative, and an astringent. In this study, we characterized the antimicrobial, antioxidant, and cytotoxic activities of cumin. E. coli, S. aureus, and S. faecalis were sensitive to various oil dilutions. The total phenol content of the essential oil was estimated to be 33.43 μg GAE/mg of the oil. The oil showed higher antioxidant activity compared with that of BHT and BHA. The cumin essential oil exhibited a dose-dependent scavenging of DPPH radicals and 5.4 μg of the oil was sufficient to scavenge 50% of DPPH radicals/mL. At a concentration of 0.1 μL/mL, oil destructed Hela cells by 79%. The antioxidant activity of cumin essential oil might contribute to its cytotoxic activity. Acute and subchronic toxicity was studied in a 30-d oral toxicity study by administration to Wistar rats of the essential oil. A 17.38% decrease in WBCs count, and 25.77%, 14.24%, and 108.81% increase in hemoglobin concentration, hematocrit, and platelet count, respectively, were noted. LDL/HDL ratio was reduced to half, which adds to the nutritional effects of cumin. Thus, cumin with a high phenolic content and good antioxidant activity can be supplemented for both nutritional purposes and preservation of foods.     

A two-phase linear programming methodology for fuzzy multi-objective mixed-model assembly line problem

We develop a fuzzy multi-objective linear programming (FMOLP) model for solving multi-objective mixed-model assembly line problem. In practice, vagueness and imprecision of the goals in this problem make the fuzzy decision-making complicated. The proposed model considers minimizing total utility work, total production rate variation, and total setup cost, using a two-phase linear programming approach. In the first phase, the problem is solved using a max–min approach. The max–min solution not being efficient, in general, we propose a new model in the second phase to maximize a composite satisfaction degree at least as good as the degrees obtained by phase one. To show the effectiveness of the proposed approach, a numerical example is solved and the results are compared with the ones obtained by the fuzzy mixed integer goal programming and weighted additive methods. The computational results show that the proposed FMOLP model achieves lower objective functions as well as higher satisfaction degrees.