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排序方式: 共有4463条查询结果,搜索用时 93 毫秒
41.
Antonio Di Nola Ioana Leuştean 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2014,18(12):2349-2363
We initiate a deep study of Riesz MV-algebras which are MV-algebras endowed with a scalar multiplication with scalars from \([0,1]\) . Extending Mundici’s equivalence between MV-algebras and \(\ell \) -groups, we prove that Riesz MV-algebras are categorically equivalent to unit intervals in Riesz spaces with strong unit. Moreover, the subclass of norm-complete Riesz MV-algebras is equivalent to the class of commutative unital C \(^*\) -algebras. The propositional calculus \({\mathbb R}{\mathcal L}\) that has Riesz MV-algebras as models is a conservative extension of ?ukasiewicz \(\infty \) -valued propositional calculus and is complete with respect to evaluations in the standard model \([0,1]\) . We prove a normal form theorem for this logic, extending McNaughton theorem for ? ukasiewicz logic. We define the notions of quasi-linear combination and quasi-linear span for formulas in \({\mathbb R}{\mathcal L},\) and relate them with the analogue of de Finetti’s coherence criterion for \({\mathbb R}{\mathcal L}\) . 相似文献
42.
Seed oils of Origanum onites L. from the Antalya and Mugla regions and O. vulgare L. from the Kirklareli region of Turkey were extracted with hexane in a Soxhlet apparatus. The oil yields were 14.1–20.0
and 18.5%, respectively. FA compositions of the seed oils were determined by GC and GC/MS. Twenty FA were identified in both
O. onites and O. vulgare seeds. The major FA of both species were linolenic (56.3–57.0%; 61.8%), linoleic (21.5–21.7%; 18.8%), oleic (8.7–8.9%; 5.9%),
palmitic (5.9–6.5%; 5.5%), stearic (2.1–2.4%; 2.1%), and (Z)-11-octadecenoic (0.6–0.8%; 0.5%), respectively. 相似文献
43.
Mustafa A. Al-Fayoumi Nidal F. Shilbayeh 《Journal of Network and Systems Management》2014,22(2):259-279
This paper studies the probability of using cloning subscriber identity module (SIM) cards in Universal Mobile Telecommunications Systems. It also explores how the mobile system can discover the cloning SIM cards as soon as possible and how to reduce the probability of using cloning SIM cards in mobile networks. The illegal mobile station attached to mobile networks can be detected by a Normal Location Area Update, a periodic area location update, and by outgoing calls that are issued from genuine mobiles. An analytical model is developed to investigate the effects of a location area update and outgoing calls issued by genuine mobiles on the use of illegal mobiles. Mobility management, such as registration, cancellation, and outgoing and incoming procedures for legal and illegal users are investigated and analysed. An analytical model to investigate the effect of outgoing call arrival rates, and location area residence time on the detected illegal user has been presented. This paper seeks to increase the security of communication by avoiding fraud of cloned mobile phones by proposing a solution to speed up the detection of cloning SIM cards. 相似文献
44.
Adina L. Ghirişan Simion Drǎgan Alexandru Pop Marinela Simihǎian Vasile Miclǎuş 《加拿大化工杂志》2007,85(6):900-905
The influence of the apatite on the efficiency of neutralization and on heavy metal removal of acid mine waste water has been studied. The analysis of the treated waste water samples with apatite has shown an advanced purification, the concentration of the heavy metals after the treatment of the waste water with apatite being 25 to 1000 times less than the Maximum Concentration Limits admitted by European Norms (NTPA 001/2005). In order to establish the macro‐kinetic mechanism in the neutralization process, the activation energy, Ea, and the kinetic parameters, rate coefficient of reaction, kr, and kt were determined from the experimental results obtained in “ceramic ball‐mill” reactor. The obtained values of the activation energy Ea >> 42 kJ mol?1 (e.g. Ea = 115.50 ± 7.50 kJ mol?1 for a conversion of sulphuric acid ηH2SO4 = 0.05, Ea = 60.90 ± 9.50 kJ mol?1 for η H2SO4 = 0.10 and Ea = 55.75 ± 10.45 kJ mol‐1 for η H2SO4 = 0.15) suggest that up to a conversion of H2SO4 equal 0.15 the global process is controlled by the transformation process, adsorption followed by reaction, which means surface‐controlled reactions. At a conversion of sulphuric acid η H2SO4 > 0.15, the obtained values of activation energy Ea < 42 kJ mol‐1 (e.g. Ea = 37.55 ± 4.05 kJ mol‐1 for η H2SO4 = 0.2, Ea = 37.54 ± 2.54 kJ mol‐1 for η H2SO4 = 0.3 and Ea = 37.44 ± 2.90 kJ mol‐1 for η H2SO4 = 0.4) indicate diffusion‐controlled processes. This means a combined process model, which involves the transfer in the liquid phase followed by the chemical reaction at the surface of the solid. Kinetic parameters as rate coefficient of reaction, kr with values ranging from (5.02 ± 1.62) 10‐4 to (8.00 ± 1.55) 10‐4 (s‐1) and transfer coefficient, kt, ranging from (8.40 ± 0.50) 10‐5 to (10.42 ± 0.65) 10‐5 (m s‐1) were determined. 相似文献
45.
In this study, phenolated wood resin was used an adsorbent for the removal of Cr(III), Ni(II), Zn(II), Co(II) ions by adsorption from aqueous solution. The adsorption of metal ions from solution was carried at different contact times, concentrations and pHs at room temperature (25°C). For individual metal ion, the amount of metal ions adsorbed per unit weight of phenolated wood resin at equilibrium time increased with increasing concentration and pH. Also, when the amounts of metal ions adsorbed are compared to each other, it was seen that this increase was order of Cr(III) > Ni(II) > Zn(II) > Co(II). This increase was order of Cr(III) > Ni(II) > Co(II) > Zn(II) for commercial phenol–formaldehyde resin. Kinetic studies showed that the adsorption process obeyed the intraparticle diffusion model. It was also determined that adsorption isotherm followed Langmuir and Freundlich models. Adsorption isotherm obtained for commercial phenol–formaldehyde resin was consistent with Freundlich model well. Adsorption capacities from Langmuir isotherm for commercial phenol–formaldehyde resin were higher than those of phenolated wood resin, in the case of individual metal ions. Original adsorption isotherm demonstrated the monolayer coverage of the surface of phenolated wood resin. Adsorption kinetic followed the intraparticle diffusion model. The positive values of ΔG° determined using the equilibrium constants showed that the adsorption was not of spontaneous nature. It was seen that values of distribution coefficient (KD) decreasing with metal ion concentration in solution at equilibrium (Ce) indicated that the occupation of active surface sites of adsorbent increased with metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2838–2846, 2006 相似文献
46.
Dual-phase(DP) steels with different martensite contents were obtained by appropriate heat treatment of an SAE1010 structural carbon steel,which was cheap and widely used in the construction industry. The corrosion behavior of DP steels in con-crete was investigated under various tempering conditions. Intercritical annealing heat treatment was applied to the reinforcing steel to obtain DP steels with different contents of martensite. These DP steels were tempered at 200,300,and 400°C for 45 min and then coo... 相似文献
47.
Ali Bayri Mustafa Sulu 《Journal of Inorganic and Organometallic Polymers and Materials》2006,16(2):185-188
This study reports the magnetic structures of newly reported trinuclear vanadium(II)–diamine complexes. Using the isotropic
Heisenberg exchange Hamiltonian, it is suggested that there are strong intramolecular antiferromagnetic interactions among
the vanadium(II) ions. It is also suggested that these complexes are good candidates to the geometrically frustrated systems.
For part 1 see A. Bayri, J. Inorg. Organomet. Polym. Mater., (in press)
An erratum to this article can be found at 相似文献
48.
Sibel Akgün Gülsüm Ekici Nilüfer Mutlu Necati Beşirli Baki Hazer 《Journal of Polymer Research》2007,14(3):215-221
Modification of chitosan by grafting of vinyl butyrate was carried out in homogeneous phase using potassium persulfate as
redox initator and 1.5% acetic acid as solvent. The percent grafting and grafting efficiency were analysed and the high grafting
efficiency up to 94% was observed. The effects of reaction variables such as monomer concentration, initiator concentration,
temperature and reaction time were investigated. It was observed that the solubility of chitosan was markedly reduced after
grafting with vinyl butyrate. The grafted product is insoluble in common organic solvents as well in dilute organic and inorganic
acids. Characterization of the graft copolymers were carried out by using Fourier Transform Infrared Spectroscopy (FTIR),
Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM) technics. Characteristic signal of carbonyl
group was observed at 1,731 cm−1 which belongs to the poly vinyl butyrate segments in the graft copolymer. The melting transition of the chitosan main chain
in the copolymer shifted to 124°C from its original value 101°C. In addition to these, we have also studied topology of the
graft copolymer and the SEM micrograph showed continuous homogenous matrix which means there is no phase separation. 相似文献
49.
Ashour Amira S. Nagieb Reham Mohamed El-Khobby Heba A. Abd Elnaby Mustafa M. Dey Nilanjan 《Multimedia Tools and Applications》2021,80(2):2583-2597
Multimedia Tools and Applications - Automated segmentation has an essential role in detecting several diseases, such as skin lesions. In segmentation, the active contour (AC) is an efficient method... 相似文献
50.
Ultra-high molecular weight polyethylene (UHMWPE) is extensively used in frictional applications due to its advanced wear resistance. This advanced polymer is reinforced with hard particulate fillers for further developments against wear conditions. Since elevated temperatures prevail in the service conditions, wear behavior of UHMWPE composites is an important issue for the engineering applications. In the present work, UHMWPE-based composites including silicon carbide (SiC) fillers were fabricated in a compression molding chamber. In the specimen preparation stage, molding pressure, filler amount, and filler particle size were varied to investigate the influence of these variables. Upon deciding the optimum parameters from the wear tests conducted at room temperature, the wear experiments were repeated for the optimum specimen at elevated temperatures, such as 40 and 60°C. According to the results, the wear behavior of the SiC/UHMWPE composites is heavily changed by the effect of elevated temperature. Adhesive effect is pronounced at elevated temperatures while the wear characteristics possess the abrasive effect in the sliding path. In addition, the composites exhibit an accelerated material loss as temperature increases during the frictional system. 相似文献