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991.
Sorin Bucsa Alexandru Serban Mugur C. Balan Claudia Ionita Gabriel Nastase Catalina Dobre Alexandru Dobrovicescu 《Entropy (Basel, Switzerland)》2022,24(2)
This case study analyzes a cryogenic air separation unit (ASU) with a production of of gaseous oxygen with a concentration greater than 98.5%, operating in Romania on a steel plant platform. The goal of the paper is to provide an extensive model of exergetic analysis that could be used in an optimization procedure when decisional parameters are changed or structural design modifications are implemented. For each key part of the Air Separation Unit, an exergetic product and fuel were defined and, based on their definition, the coefficient of performance of each functional zone was calculated. The information about the magnitude of the exergetic losses offers solutions for their future recovery. The analysis of the exergy destructions suggests when it is worth making a larger investment. The exergetic analysis of the compression area of the ASU points out an exergy destruction and loss of 37% from the total plant’s electrical energy input. The exergy loss with the heat transferred to the cooling system of compressors can be recovered; for the exergy destruction portion, the challenge between investment and operating costs should be considered. The exergy destruction of the air separation columns found the High Pressure Column (HPC) to be more destructive than the Low Pressure Column. The share of the exergy destruction in the total plant’s electrical energy input is 8.3% for the HPC. The local COP of the HPC, calculated depending on the total exergy of the local product and fuel, is 62.66%. The calculus of the air separation column is performed with the ChemSep simulator. 相似文献
992.
Novel linear supramolecular polymers were successfully constructed by self-assemblies of coumarin-bridged bifunctional UPy derivative.Benefitting from the photodimerization ability of the coumarin moieties,the linear supramolecular polymers could form the large three-dimensional polymer networks upon UV light irradiation via photo-cross-linking,which provides a viable and alternative procedure to modulate the properties of supramolecular polymers. 相似文献
993.
Stability of crude oil distillation units was analyzed with mathematical models developed using Aspen Hysys. Parametrical sensitivities of light fractions yields, heat duties and steam load of column trays to perturbations of superheated steam flow rate were estimated. Objective function based on the light products yields and energy consumption for distillation was formed. The maxima of the objective function were calculated depending on operational parameters and flow rate of water steam. 相似文献
994.
A new multiobjective procedure for solving nonconvex environmental/economic power dispatch
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In this article, an improved multiobjective chaotic interactive honey bee mating optimization (CIHBMO) is proposed to find the feasible optimal solution of the environmental/economic power dispatch problem with considering operational constraints of the generators. The three conflicting and noncommensurable: fuel cost, pollutant emissions, and system loss, should be minimized simultaneously while satisfying certain system constraints. To achieve a good design with different solutions in a multiobjective optimization problem, Pareto dominance concept is used to generate and sort the dominated and nondominated solutions. Also, fuzzy set theory is used to extract the best compromise solution. The propose method has been individually examined and applied to the standard Institute of Electrical and Electronics Engineers (IEEE) 30‐bus six generator, IEEE 180‐bus 14 generator and 40 generating unit (with valve point effect) test systems. The computational results reveal that the multiobjective CIHBMO algorithm has excellent convergence characteristics and is superior to other multiobjective optimization algorithms. Also, the result shows its great potential in handling the multiobjective problems in power systems. © 2014 Wiley Periodicals, Inc. Complexity 20: 47–62, 2014 相似文献
995.
Z. Bashir 《Journal of Polymer Science.Polymer Physics》1994,32(6):1115-1128
Differences in the x-ray diffraction pattern of polyacrylonitrile (PAN) have been observed, both here, as well as in the work reported in the literature. Various workers have cited grossly differing unit cells for PAN and this has never been explained. In this work, it is shown that in dry samples, the diffraction pattern contains only two equatorial peaks, d1 ≈ 5.3 Å and d2 ≈ 3.0 Å. This is consistent with a hexagonal packing of rod-like chains of PAN with no chain-axis order. However, in solvent-plasticized films, the diffraction pattern is altered. It is proposed that certain solvents cause a hexagonal to orthohombic transition. However, the orthorhombic polymorph appears to be a solvated form, where the solvent has co-crystallized with the polymer. After removal of solvent, the structure reverts to hexagonal packing. Hence, it is suggested that the discrepancy in cell parameters cited in the literature, particularly when large cell dimensions are quoted, may be due to the inadvertent presence of solvent which could have been introduced during sample preparation. Similarities with solvated crystls in other polymeric systems are also briefly discussed. © 1994 John Wiley & Sons, Inc. 相似文献
996.
We prove that the holomorphic unipotent Jacobian conjecture is valid when n = 3. 相似文献
997.
Soogil Seo 《Compositio Mathematica》2003,137(1):91-98
The purpose of this paper is to investigate a conjecture about the universality of the circular distribution made by Robert Coleman. The algebraic property of the universal distribution is the main ingredient in studying Euler system of Kolyvagin and Rubin. We study the universality of the circular distribution by using the Iwasawa theory and the theory of the Euler systems. The conjecture is a characterization of Euler systems in the case of number field. The results here assert that Euler systems are essentially made out of cyclotomic units. 相似文献
998.
999.
1000.
We prove that any binary relation with underlying set (base) E with cardinality n > 6 is reconstructible from its restrictions of cardinality 2, 3, 4 and (n - 1). In part I we characterize relations R and R' on the same base E such that R/X and R'/X are isomorphic for every subset X of E with cardinality 2, 3, 4. In part II we shall prove that R and R' are isomorphic as soon as n > 6 when R/X and R/X' are isomorphic for every subset X of E with cardinality 2, 3, 4 and (n - 1). 相似文献