212,377 research outputs found
Hopf bifurcation analysis in a modified R&D model with delay
No full textfirst_pageDownload PDFsettingsOrder Article Reprints Open AccessArticle Hopf Bifurcation Analysis in a Modified R&D Model with Delay by Yang Cao 1,Ferrara Massimiliano 2,3,4,*ORCID,Gangemi Mariangela 2,4ORCID andGuerrini Luca 4,5ORCID 1 School of Cyber Science and Engineering, Southeast University, Nanjing 210096, China 2 Department of Law, Economics and Human Sciences, “Mediterranea” University of Reggio Calabria, Via dell’Università, 25, 89124 Reggio Calabria, Italy 3 ICRIOS—The Invernizzi Centre for Research in Innovation, Organization, Strategy and Entrepreneurship, Department of Management and Technology, Bocconi University, Via Sarfatti, 25, 20100 Milano, Italy 4 Decision Lab, “Mediterranea” University of Reggio Calabria, Via dell’Università, 25, 89124 Reggio Calabria, Italy 5 Department of Management, Polytechnic University of Marche, Piazzale Martelli 8, 60121 Ancona, Italy * Author to whom correspondence should be addressed. Axioms 2022, 11(4), 148; https://doi.org/10.3390/axioms11040148 Submission received: 28 November 2021 / Revised: 20 March 2022 / Accepted: 21 March 2022 / Published: 24 March 2022 (This article belongs to the Special Issue Dynamical Systems: Advances in Theory and Applications) Downloadkeyboard_arrow_down Browse Figures Versions Notes Abstract We consider a duopoly game model of R&D (research and development) rivalry between two high-tech firms with time delay, in which a monopoly sector with R&D spillover is studied using a mixture of game theory and nonlinear dynamics theory. The local asymptotic stability of the equilibrium point is studied by analyzing the corresponding characteristic equation. It is found that the delay can lead the system dynamic behavior to exhibit stability switches and Hopf bifurcations appear
Novel sol–gel preparation of (PO)–(CaO)–(NaO)–(TiO) bioresorbable glasses (X = 0.05, 0.1, and 0.15)
No full textQuaternary phosphate-based glasses in the PO–CaO–NaO–TiO system with a fixed PO and CaO content of 40 and 25 mol% respectively have been successfully synthesised via sol–gel method and bulk, transparent samples were obtained. The structure, elemental proportion, and thermal properties of stabilised sol–gel glasses have been characterised using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), P nuclear magnetic resonance (P NMR), titanium K-edge X-ray absorption near-edge structure (XANES), fourier transform infrared (FTIR) spectroscopy, and differential thermal analysis (DTA). The XRD results confirmed the amorphous nature for all stabilized sol–gel derived glasses. The EDX result shows the relatively low loss of phosphorus during the sol–gel process and Ti K-edge XANES confirmed titanium in the glass structure is in mainly six-fold coordination environment. The P NMR and FTIR results revealed that the glass structure consist of mainly Q and Q phosphate units and the Ti cation was acting as a cross-linking between phosphate units. In addition DTA results confirmed a decrease in the glass transition and crystallisation temperature with increasing NaO content. Ion release studies also demonstrated a decrease in degradation rates with increasing TiO content therefore supporting the use of these glasses for biomedical applications that require a degree of control over glass degradation. These sol–gel glasses also offer the potential to incorporate proactive molecules for drug delivery application due to the low synthesis temperature employed
Melt densities in the CaO-FeO-Fe2O3-SiO2 system and the compositional dependence of the partial molar volume of ferric iron in silicate melts
No full textThe densities of 10 melts in the CaO-FeO-Fe2O3-SiO2 system were determined in equilibrium with air, in the temperature range of 1200 to 1550°C, using the double-bob Archimedean technique. Melt compositions range from 6 to 58 wt% SiO2, 14 to 76 wt% Fe2O3 and 10 to 46 wt% CaO. The ferric-ferrous ratios of glasses drop-quenched from loop fusion equilibration experiments were determined by 57Fe Mössbauer spectroscopy.
Melt densities range from 2.689 to 3.618 gm/cm3 with a mean standard deviation from replicate experiments of 0.15%. Least-squares regressions of molar volume versus molar composition have been performed and the root mean squared deviation shows that a linear combination of partial molar volumes for the oxide components (CaO, FeO, Fe2O3 and SiO2) cannot describe the data set within experimental error. Instead, the inclusion of excess terms in CaFe3+ and CaSi (product terms using the oxides) is required to yield a fit that describes the experimental data within error. The nonlinear compositional-dependence of the molar volumes of melts in this system can be explained by structural considerations of the roles of Ca and Fe3+.
The volume behavior of melts in this system is significantly different from that in the Na2O-FeO-Fe2O3-SiO2 system, consistent with the proposal that a proportion of Fe3+ in melts in the CaO-FeO-Fe2O3-SiO2 system is not tetrahedrally-coordinated by oxygen, which is supported by differences in 57Fe Mössbauer spectra of glasses. Specifically, this study confirms that the 57Fe Mössbauer spectra exhibit an area asymmetry and higher values of isomer shift of the ferric doublet that vary systematically with composition and temperature (this study; Dingwell and Virgo, 1987, 1988). These observations are consistent with a number of other lines of evidence (e.g., homogeneous redox equilibria, Dickenson and Hess, 1986; viscosity, Dingwell and Virgo, 1987,1988). Two species of ferric iron, varying in proportions with temperature, composition and redox state, are sufficient to describe the above observations.
The presence of more than one coordination geometry for Fe3+ in low pressure silicate melts has several implications for igneous petrogenesis. The possible effects on compressibility, the pressure dependence of the redox ratio, and redox enthalpy are briefly noted
Extensive evaluation of a framenet-wordnet mapping resource
No full textLexical resources are basic components of many text processing system devoted to information extraction, question answering or dialogue. In paste years many resources have been developed such as FrameNet and WordNet. FrameNet describes prototypical situations (i.e. Frames) while WordNet defines lexical meaning (senses) for the majority of English nouns, verbs, adjectives and adverbs. A major difference between FrameNet and WordNet refers to their coverage. Due of this lack of coverage, in recent years some approaches have been studied to make a bridge between this two resources, so a resource is used to extend the coverage of the other one. The nature of these approaches leave from supervised to supervised methods. The major problem is that there is not a standard in evaluation of the mapping. Each different work have tested own approach with a custom gold standard. This work give an extensive evaluation of the model proposed in (De Cao et al., 2008) using gold standard proposed in other works. Moreover this work give an empirical comparison between other available resources. As outcome of this work we also release the full mapping resource made according to the model proposed in (De Cao et al., 2008)
Process engineering and development of post-combustion CO2 separation from fuels using limestone in CaO-looping cycle
No full textGlobal CO2 emissions produced by energy-related processes, mainly power plants, have increased rapidly in recent decades; and are widely accepted as the dominant contributor to the greenhouse gas (GHG) effect and consequent climate changes. Among countermeasures against the emissions, CO2 capture and storage (CCS) is receiving much attention. Capture of CO2 is the core step of CCS as it contributes around 75% of the overall cost, and may increase the production costs of electricity by over 50%. The reduction in capture costs is one of the most challenging issues in application of CCS to the energy industry. Using limestone in CaO-looping cycles is a promising capture technology to provide a cost-effective separation process to remove CO2 content from power plants operations. Limestone has the advantage of being relatively abundant and cheap, and that has already been widely used as a sorbent for sulphur capture. However, this technology suffers from a critical challenge caused by the decay in the sorbent capture capacity during cyclic carbonation/calcination, which results in the need for more sorbent make-up; hence a reduction in cost efficiency of the technology. The performance of sorbent influenced by several operating and reaction conditions. Therefore, much research involves investigation of influencing factors and different methods to reduce the sorbent deactivation. Cont/d
CaO-Based CO<sub>2</sub> Sorbents with a Hierarchical Porous Structure Made via Microfluidic Droplet Templating
No full textCalcium looping,
a CO2 capture technique based on the
cyclic carbonation and calcination of CaO, is a promising short- to
midterm solution to reduce CO2 emissions. However, CaO
suffers from sintering under industrially relevant operating conditions,
which reduces rapidly its cyclic CO2 uptake capacity. Here,
we report the design and manufacture of a hierarchical, porous (HP)
CaO-based CO2 sorbent. The hierarchically porous sorbent
is created through the assembly of calcium carbonate nanoparticles
and monodisperse oil droplets generated via microfluidic emulsification.
The structure of the sorbent is stabilized by an Al2O3 coating via atomic layer deposition (ALD). The sorbent outperformed
the CO2 uptake of the reference limestone by ca. 140%.
The improved CO2 uptake capacity is attributed to (i) the
stabilization of the micro- and mesoporous structure of the material
by the formation of Ca–Al mixed oxides, that is, Ca12Al14O33 and Ca3Al2O6, and (ii) an improved mass transport within the sorbent particles
owing to the HP structure of the material
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
R an ſpital ze ſante gallen dem heiligen geiſte - 1277.
No full textR., die Ehefrau des Herrn Ludwigs von Prassberg, beurkundet, daß sie dem Spital vom Heiligen Geist zu St. Gallen mit Einwilligung ihres Ehemanns und ihrer Kinder ihr Eigen Wilen bei Riet gegeben hat mit der Bedingung, daß das Spital rᷝswenne diz selbe gvͦt ze boͮwe wirt braht, der R. jährlich 10 Schillinge Konstanzer Pfennige bis zu ihrem Tode geben soll, wenn sie diese nehmen will. Nach ihrem Tode hört diese Verpflichtung auf. --{'name': 'BAdW', 'uri': 'badw.png'
Stabilization/Solidification of Nitrobenzene Contaminated Soil based on Hydrophobilized CaO
No full textAbstractLime, one of the common binders used in Solidification/Stabilization (S/S), is not adequate to immobilize toxic organic compounds of high-concentration released into soil by accidents in petrochemical and chemical industries. CaO, the main composition of lime, was hydrophobilized with stearic acid (SA) and silane coupling agent (KH570) to improve its fixation of nitrobenzene in S/S remediation of contaminated soil in present work, and the effect of hydrophobilized CaO on toxic organic compound encapsulation was evaluated through leaching and volatilization tests. Results showed that the binder composed of 20% SA hydrophobilized CaO together with 10% original CaO could reduce nitrobenzene's volatilization ratio to 0.096% and leaching ratio to 8.79%, while the nitrobenzene's volatilization ratio is 0.413% and leaching ratio is 35.48% with 30% original CaO as the binder
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