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141.
Jan Mosio-Mosiewski Marek Warzala Ireneusz Morawski Tadeusz Dobrzanski 《Fuel Processing Technology》2007
The thermal cracking and catalytic cracking processes of low-density polyethylene were studied in a closed autoclave. The compositions of gaseous and liquid products were analysed by means of GC/FID and GS/MS chromatographic methods. The fractional composition of liquid products was found by distillation. Increased temperature of PE depolymerisation process increases the production of gaseous products and low-boiling liquid compounds; more aromatic hydrocarbons are formed instead of alkenes. When a lower temperature and longer time are adopted for the process to reach the assumed conversion, more straight chained hydrocarbons are produced. The acidic aluminosilicate catalyst yields more low-boiling liquid fractions, more isoalkanes and more aromatics. The neutral alumina is favourable for the production of alkenes and vacuum gas oil fraction in comparison to a non-catalytic process. The Ni–Mo/Al2O3 catalyst is efficient in hydrogenation of depolymerisation products. The reaction products contain only saturated compounds then and no aromatics are formed. 相似文献
142.
P.G.Joshi R.J.Cruse R.J.Pickwell K.J.Weller M.H.Hofstetter E.R.Pohl M.F.Stout F.D.Osterholtz 涂学忠摘译 《轮胎工业》2005,25(2):96-103
填充白炭黑的低滚动阻力轮胎的开发不断获得新进展。与填充普通炭黑的轮胎相比,白炭黑轮胎不仅降低了油耗,而且具有优异的牵引性能和与后者相当的磨耗寿命。高分散性白炭黑和多硫化双-烷氧基硅烷的发展使高填充白炭黑轮胎商品化获得重大突破。炭黑胶料和白炭黑-硅烷胶料的能耗散机理差异很大, 相似文献
143.
Amare Haileslassie Joerg A. Priess Edzo Veldkamp Jan Peter Lesschen 《Nutrient Cycling in Agroecosystems》2006,75(1-3):135-146
Low agricultural productivity caused by soil degradation is a serious problem in the Ethiopian Highlands. Here, we report how differences in soil fertility management between farming systems, based either on enset (Ensete ventricosum) or on teff (Eragrostis tef) as the major crops, affect the extent of nutrient stocks, balances and ecosystem sustainability. We collected information on farmers’ resources and nutrient management practices from stratified randomly selected households in two watersheds in the Central Highlands of Ethiopia. In addition, we collected soil samples from each land use and calculated nutrient stocks, partial and full nutrient balances (N, P and K) for one cropping season. Our results show that farmers in the two farming systems manage their soils differently and that nutrient inputs were positively related to farmers’ wealth status. The watershed with the enset-based system had higher soil N and K stocks than the watershed with the teff-based system, while P stocks were not different. Management related N?and K fluxes were more negative in the teff-based system (?28 kg N ha?1 yr?1 and ?34 kg K ha?1 yr?1) than in the enset-based system (?6 kg N ha?1 yr?1 and ?14 kg K ha?1 yr?1) while P fluxes were almost neutral or slightly positive. Within the enset-based system, a strong redistribution of N, P and K took place from the meadows and cereals (negative balance) to enset (positive balances). Although in the teff-based system, N, P and K were redistributed from meadows, small cereals and pulses to maize, the latter still showed a negative nutrient balance. In contrast to nutrient balances at land use level, nutrient balances at the watershed scale masked contrasting areas within the system where nutrient oversupply and deficiencies occurred. 相似文献
144.
With the help of DTA, DTG elementary analysis of carbonized residues and ESR spectroscopy the influence of anionic form on thermooxidation of trimethylammoniumhydroxyprophyl (TMAHP)–cellulose was studied. At 300°C the percentage of carbon in carbonized residue thermolyzed in oxidative atmosphere is higher than for the sample degraded in inert atmosphere. The percentage of hydrogen decreases simultaneously. The concentration of free radicals in thermolyzed residue also increases due to the presence of oxygen. We propose that oxygen is abstracting the hydrogen atoms from polysaccharide and unpaired electrons on carbon atoms are produced. At 400°C the percentage of carbon in residues prepared at inert atmosphere is higher than for residue formed at oxidative atmosphere. Also the concentration of free radicals in thermolyzed residues obtained in inert atmosphere is greater than for those from oxidative ones. That is why suppose that at this temperature oxygen is bonded to polysaccharide residue and free radicals are terminated. From the semiquantitative DTA we can make the following sequence of samples according to their increasing thermooxidative effect: unmodified cellulose < A–HSO < A–Br? < A–I? < A–NO < A–H2PO < A–CH3COO? < A–HCO < A–F? < A–Cl?1 < A–OHp?. 相似文献
145.
Radim Belohlavek Dhouha Grissa Sylvie Guillaume Engelbert Mephu Nguifo Jan Outrata 《Annals of Mathematics and Artificial Intelligence》2014,70(1-2):151-184
Measures of interestingness play a crucial role in association rule mining. An important methodological problem, on which several papers appeared in the literature, is to provide a reasonable classification of the measures. In this paper, we explore Boolean factor analysis, which uses formal concepts corresponding to classes of measures as factors, for the purpose of clustering of the measures. Unlike the existing studies, our method reveals overlapping clusters of interestingness measures. We argue that the overlap between clusters is a desired feature of natural groupings of measures and that because formal concepts are used as factors in Boolean factor analysis, the resulting clusters have a clear meaning and are easy to interpret. We conduct three case studies on clustering of measures, provide interpretations of the resulting clusters and compare the results to those of the previous approaches reported in the literature. 相似文献
146.
In this paper, we present an invariant‐set‐based method for actuator and sensor fault detection and isolation in Lure systems. The Lure plant is controlled by an observer‐based feedback tracking controller, designed for the nominal (fault‐free) system. Suitable residual signals are constructed from measurable system outputs and estimates associated with the nominal observer. Faults are diagnosed by online contrasting the residual signal trajectories against sets of values that the residuals are shown to attain under healthy or faulty operation. These values are obtained via set‐invariance analysis of the system closed‐loop trajectories. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
147.
The study reported in this article deals with understanding the physical, chemical and microstructural differences in sulfate attack from seawater and groundwater. Portland cement mortars were completely immersed in solutions of seawater and groundwater. Physical properties such as length, mass, and compressive strength were monitored periodically. Thermal analysis was used to study the relative amounts of phases such as ettringite, gypsum, and calcium hydroxide, and microstructural studies were conducted by scanning electron microscopy. Portland cement mortars performed better in seawater solution compared to groundwater solution. The difference in performance could be attributed to the reduction in the quantity of the expansive attack products (gypsum and ettringite). The high Cl concentration of seawater could have played an important role by binding the C3A to form chloroaluminate compounds, such as Friedel's salt (detected in the microstructural studies), and also by lowering the expansive potential of ettringite. Furthermore, the thicker layer of brucite forming on the specimens in seawater could have afforded better protection against ingress of the solution than in groundwater. 相似文献
148.
The crystal structure and molecular conformation of 2-cyano-4-bromo-4′-N,N-diethylaminoazobenzene (C17H17N4Br, mol. wt. = 357·2 a.m.u) has been determined from X-ray diffraction data; triclinic, P (No. 2), a = 10·132(11) Å, b = 12·216(16) Å, c = 6·966(11) Å, α = 104·21(9)°, β = 92·67(12)°, γ = 97·22(7)°, V = 826·5(9) Å3, Z = 2, Dc = 1·436 g cm?3, F(000) = 378, λ(MoKα) = 0·71069 Å, μ(MoKα) = 26·0 cm?1. The structure was solved by the multiple solution direct method and refined by full-matrix least-squares to R = 0·059 for 1538 independent observed reflections. The azobenzene skeleton is planar to within 0·06 Å. Most significant bonding data are: NN, 1·290(8) Å; BrC, 1·866(6) Å; mean CN (azo) 1·380(8) Å; NNC, 113·6(4) and 115·3(4)°; NCC (cis relative to NN) 125·9(4)° and 126·7(4)°; NCC (trans) 116·8°(5)° and 116·1(4)°. 相似文献
149.
Jan Willem?van?GroenigenEmail author Pieter Jan?Georgius Chris?van?Kessel Eduard W.J.?Hummelink Gerard L.?Velthof Kor B.?Zwart 《Nutrient Cycling in Agroecosystems》2005,72(1):13-25
Studies on emissions of nitrous oxide (N2O) from agricultural soils mostly focus on fluxes between the soil and the atmosphere or are limited to the atmosphere in
the topsoil. However, in soils with shallow water tables, significant N2O formation may occur closer to the groundwater. The aims of this study were (i) to determine the importance of subsoil N2O formation in a sandy soil; and (ii) to obtain a quantitative insight in the contribution of subsoil N2O to the overall losses of N2O to the environment. We applied 15N labeled fertilizer at a rate of 5.22 kg 15N ha−1; 50% as Ca(NO3)2 and 50% as NH4Cl, on a mesic typic Haplaquod seeded with potatoes (Solanum tuberosum L.), and traced soil N2O concentrations and fluxes over a one-year period. Throughout the year, total N2O and the amount of 15N recovered in soil N2O were highest in the subsoil, with a maximum concentration at 48 cm depth in mid-February of 19900 μl m−3 and 24 μg 15N m−3, respectively. The maximum concentration coincided with the highest water-filled pore space of 71%. The cumulative flux of
N2O was 446 g N2O-N ha−1, the recovery of 15N in this flux was 0.06%. During the summer, maximum fluxes followed high soil N2O concentrations. During winter, no such relation was found. We concluded that the formation of N2O was the highest in the subsoil, largely controlled by water-filled pore space rather than NO3− concentration or temperature. Although high subsoil N2O concentrations did not lead to high surface fluxes of N2O in the winter, artificial draining may lead to high indirect N2O emissions through supersaturated drainage water. 相似文献
150.
Huong Thi Le Inge D Brouwer Jan Burema Khan Cong Nguyen Frans J Kok 《Nutrition journal》2006,5(1):1-8