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91.
Silicon - Informed through synthesis and characterization of NH 3 TPD, BET techniques, the current study investigated the right contribution of silicon and water content on a 9 sample SAPO-34... 相似文献
92.
In this study, high density polyethylene (HDPE) was combined with dicumyl peroxide (DCP) to produce crosslinked parts via rotational molding. The effect of DCP content (0.1–2.5 phr) on the crosslinking degree was investigated to determine its effect on the chemical, mechanical, physical, and thermal properties of HDPE. The gel content and crosslink density was found to increase with DCP content. These trends led to a reduction in the degree of crystallinity, melting, and crystallization temperature. Thermogravimetric analysis (TGA) showed that crosslinked HDPE (xHDPE) has higher thermal stability than the neat matrix in both air and nitrogen atmosphere. In addition, a direct relationship was observed between improved thermal resistance and higher impact strength. Finally, relationships between the tensile properties of xHDPE and the degree of crystallinity were observed, which were all controlled by the level of crosslinking. These results have the potential to advance the manufacturing of high performance materials suitable for a wide range of applications such as automotive parts, agricultural products, chemical storage tanks, large waste containers, and fuel tanks in general. 相似文献
93.
Mohammad Hossein Keshavarz Hamid Reza Pouretedal Ali Reza Ghaedsharafi Seyed Ehsan Taghizadeh 《Propellants, Explosives, Pyrotechnics》2014,39(6):815-818
A reliable simple method for prediction of the standard Gibbs energy of formation (ΔfGθ) of energetic compounds containing nitroaromatic, acyclic, and cyclic nitramine, nitrate ester, and nitroaliphatic compounds is introduced herein. The method is based on the contribution of elemental composition (ΔfGelemθ) and the correcting function for the presence of additive and non‐additive molecular fragments (ΔfGcorrθ). In presence of some molecular moieties, ΔfGcorrθ may increase or decrease the value of ΔfGelemθ, depending on the intermolecular interactions. The experimental root‐mean‐square error (RMSE) of the novel correlation (22.7 kJ mol−1) is quite good. For some energetic compounds, where the computed values of two complex models of the quantitative structure‐property relationship (QSPR) theory were available, the experimental RMSE developed by the new method is smaller than the values obtained by QSPR method. 相似文献
94.
The scratch behavior of butyl-acrylate rubber-modified styrene-acrylonitrile (ASA) upon high temperature annealing is investigated following the ASTM D7027/ISO 19252 linearly increasing normal load test methodology. The critical normal loads at the onset of the major deformation transitions along the scratch path, such as groove formation, scratch visibility, microcrack formation, and plowing, are reported and quantitatively analyzed. It is found that the scratch resistance improves with high temperature annealing, i.e., 30 °C above Tg, as compared to annealing below or around Tg. Microscopic investigation suggests that the increase in scratch resistance is related to the changes in surface morphology of the polymer. It is concluded that performing high temperature annealing enhances the scratch performance without compromising ASA bulk properties. Implication of the present study for improving scratch resistance of polymers is discussed. 相似文献
95.
Auob Safari Jaber Safdari Hossein Abolghasemi Mostafa Forughi Mahnaz Moghaddam 《Chemical Engineering Research and Design》2012
In this research work, the volumetric overall mass transfer coefficient based on continuous-phase (Koca) and axial dispersion coefficients of phases (Ec, Ed) in a pilot Pulsed Packed Liquid Extraction Column (PPLEC) have been studied using plug flow model (PFM) and axial dispersion model (ADM). Experiments have been carried out using standard systems of water/acetone/toluene and water/acetone/n-butyl–acetate. Values of Koca evaluated by ADM are greater than those of PFM by about 20% indicating that the axial mixing lowers the performance of PPLEC. It was found that the drop-size distribution is the main cause of the axial mixing in PPLEC. Increase in dispersed phase flow rate (Qd), increases all Koca, Ed and Ec and the minimum values of both Ed and Ec and the maximum values of Koca are in pulse intensity ranges of 0.8–1 cm/s. Finally, three empirical correlations are proposed for the prediction of these parameters which are in good agreement with the experimental data. 相似文献
96.
97.
Ahmad Mozaffari Alireza Fathi Amir Khajepour Ehsan Toyserkani 《Applied Soft Computing》2013,13(3):1505-1519
With the rapid growth of laser applications and the introduction of high efficiency lasers (e.g. fiber lasers), laser material processing has gained increasing importance in a variety of industries. Among the applications of laser technology, laser cladding has received significant attention due to its high potential for material processing such as metallic coating, high value component repair, prototyping, and even low-volume manufacturing. In this paper, two optimization methods have been applied to obtain optimal operating parameters of Laser Solid Freeform Fabrication Process (LSFF) as a real world engineering problem. First, Particle Swarm Optimization (PSO) algorithm was implemented for real-time prediction of melt pool geometry. Then, a hybrid evolutionary algorithm called Self-organizing Pareto based Evolutionary Algorithm (SOPEA) was proposed to find the optimal process parameters. For further assurance on the performance of the proposed optimization technique, it was compared to some well-known vector optimization algorithms such as Non-dominated Sorting Genetic Algorithm (NSGA-II) and Strength Pareto Evolutionary Algorithm (SPEA 2). Thereafter, it was applied for simultaneous optimization of clad height and melt pool depth in LSFF process. Since there is no exact mathematical model for the clad height (deposited layer thickness) and the melt pool depth, the authors developed two Adaptive Neuro-Fuzzy Inference Systems (ANFIS) to estimate these two process parameters. Optimization procedure being done, the archived non-dominated solutions were surveyed to find the appropriate ranges of process parameters with acceptable dilutions. Finally, the selected optimal ranges were used to find a case with the minimum rapid prototyping time. The results indicate the acceptable potential of evolutionary strategies for controlling and optimization of LSFF process as a complicated engineering problem. 相似文献
98.
This paper presents a long-term dynamic multi-objective planning model for distribution network expansion along with distributed energy options. The proposed model optimizes two objectives, namely costs and emissions and determines the optimal schemes of sizing, placement and specially the dynamics (i.e., timing) of investments on distributed generation units and network reinforcements over the planning period. An efficient two-stage heuristic method is proposed to solve the formulated planning problem. The effectiveness of the proposed model is demonstrated by applying it to a distribution network and comparing the simulation results with other methods and models. 相似文献
99.
Hamed Aminzadeh Ehsan Rakhshanizadeh Hamid Emamjomeh 《Analog Integrated Circuits and Signal Processing》2014,78(1):253-256
Hybrid cascode feedforward compensation (HCFC) is proposed for low-power area-efficient three stage amplifiers driving large capacitive loads. With no overhead in power or area, the total compensation capacitor is divided and shared between two internal high-speed loops instead of solely one loop as is common in prior art. Detailed analysis of HCFC shows significant improvement in terms of stability and bandwidth. This is verified for a 1.2-V amplifier driving a 500-pF capacitive load in 90-nm CMOS technology, where HCFC reduces the total capacitor size and improves the gain-bandwidth by at least 30 and 40 %, respectively, compared to the prevailing schemes. 相似文献
100.
In this work, the method of moments is used for solution of population balance equations appearing in modeling of emulsion polymerization (EP). The zero-one model without coagulation effect and the pseudo-bulk model including coagulation effect are investigated as two common approaches for modeling EP processes. The fixed quadrature method is used to close the set of moment equations, and the maximum entropy approach is applied to reconstruct the particle size distribution from a finite number of its moments. Comparing the results with those obtained by the high-precision finite volume technique indicates that, despite the low computational load of the moment method, it has an acceptable accuracy. These features support use of the moment technique for other applications such as on-line control or optimization in particulate processes. 相似文献