11351 research outputs found
Sort by
On the Stability of a Three Species Syn-Eco-System with Mortality Rate for the Third Species
Get PDFThe system comprises of a commensal (S1) common to two hosts S2 and S3 with mortality rate for the host (S3). Here all the three species posses limited resources. The model equations constitute a set of three first order non-linear simultaneous coupled differential equations. Criteria for the asymptotic stability of all the eight equilibrium states are established. Trajectories of the perturbations over the equilibrium states are illustrated. Further the global stability of the system is established with the aid of suitably constructed Liapunov’s function and the numerical solutions for the growth rate equations are computed using Runge-Kutta fourth order scheme
Implicit-explicit higher-order time integration schemes for computations of structural dynamics with fluid-structure interaction
Get PDFIn this paper higher order implicit Runge-Kutta schemes are applied to fluid-structure interaction (FSI) simulations. A staggered approach with a structural predictor is applied to an FSI problem. The equations governing the dynamics of the structure are integrated in time by the Explicit Single Diagonal Implicit Runge-Kutta (ESDIRK) schemes and the arbitrary high order finite volume scheme is taken as the fluid solver. The performance of the ESDIRK scheme of order of convergence three to five is tested. Comparative studies with other time integration schemes which have been successfully applied to FSI problems are undertaken. Comparisons to test the performance of the scheme are carried out. The staggered approach is applied to couple the structure and the compressible fluid, therefore the added mass effect is not considered. However the influence of the structural predictors is analyzed through energy conservation
Characterization of Gamma Hemirings by Generalized Fuzzy Gamma Ideals
Get PDFThis paper has explored theoretical methods of evaluation in the identification of the boundedness of the generalized fuzzy gamma ideals. A functional approach was used to undertake a characterization of this structure leading to a determination of some interesting gamma hemirings theoretic properties of the generated structures. Gamma hemirings are the generalization of the classical agebraic structure of hemirings. Our aim is to extend this idea and, to introduce the concept of generalized fuzzy gamma ideals, generalized fuzzy prime (semiprime) gamma ideals, generalized fuzzy h -gamma ideals and generalized fuzzy k - gamma ideals of gamma hemirings and related properties are investigated. We have shown that intersection of any family of generalized fuzzy (left, right) h - gamma ideals (k-gamma ideals) of a hemiring is a generalized fuzzy (left, right) h -gamma ideal (k-gamma ideal) of H. Similarly we proved that the intersection of any family of generalized fuzzy prime (resp. semiprime) gamma ideals of H is a generalized fuzzy prime (resp. semiprime) gamma ideal of H. We have proved that a fuzzy subset μ of H is fuzzy h -gamma ideal (k-gamma ideal) if and only if μ is a generalized fuzzy h -gamma ideal (k-gamma ideal) of H. Further level cuts provide a useful linkage betwean the classical set theorey and the fuzzy set theorey. Here we use this linkage to investigate some useful aspects of gamma hemirings and characterize the gamma hemmirings through level cuts in terms of generalized fuzzy (left, right, prime, semiprime) gamma ideals of gamma hemirings. We have also used the concept of support of a fuzzy set in order to obtain some interesting results of gamma hemirings using the generalized fuzzy (left, right, prime, semiprime) gamma ideals of hemirings
Accurate spectral solutions of first and second-order initial value problems by the ultraspherical wavelets-Gauss collocation method
Get PDFIn this paper, we present an ultraspherical wavelets-Gauss collocation method for obtaining direct solutions of first- and second-order nonlinear differential equations subject to homogenous and nonhomogeneous initial conditions. The properties of ultraspherical wavelets are used to reduce the differential equations with their initial conditions to systems of algebraic equations, which then must be solved by using suitable numerical solvers. The function approximations are spectral and have been chosen in such a way that make them easy to calculate the expansion coefficients of the thought-for solutions. Uniqueness and convergence of the proposed function approximation is discussed. Four illustrative numerical examples are considered and these results are comparing favorably with the analytic solutions and proving more accurate than those discussed by some other existing techniques in the literature
The effect of metal ions as co-catalysts on acidic ionic liquid catalyzed single-step saccharification of corn stover in water
No full textThe effects of adding Cr3+, Mn2+, Fe3+, Co2+ Ni2+, Cu2+, Zn2+ and La3+ chlorides as co-catalysts to 1-(1-propylsulfonic)-3-methylimidazolium chloride acidic ionic liquid catalyzed saccharification of corn stover in aqueous medium was studied at 140-170°C, by measuring the total reducing sugar (TRS) and glucose yields. The samples with Mn2+, Fe3+, Co2+ as co-catalysts produced higher TRS yields compared to the sample without the metal ions. The Mn2+ produced the highest catalytic effect enhancements and produced TRS yields of 68.0%, 72.9%, 90.2% and 87.9% at 140, 150, 160 and 170°C respectively; whereas the corn stover samples without the Mn2+ produced TRS yields of 42.9%, 52.3%, 54.4% and 53.5% at the same four temperatures. At higher temperatures of 160 and 170°C, all metal ions studied produced significant enhancements in glucose yields, except Cr3+. The addition of La3+ as a co-catalyst produced the highest glucose yield improvement
Pd/C catalyzed conversion of levulinic acid to γ-valerolactone using alcohol as a hydrogen donor under microwave conditions
No full textLevulinic acid can be converted to γ-valerolactone in 83-86% yield under microwave heating with 10 mg of 5% Pd/C per mmol levulinic acid as the catalyst and 2.0 equivalents of KOH in ethanol or iso-propanol. The alcohol is used as the hydrogen source as well as the solvent. Pd/C catalyst could be reused for five catalytic cycles without appreciable loss in activity
Algorithms for asset replacement under limited technological forecast
No full textThe optimal asset replacement is analyzed when the future course of technological change is known on a limited future horizon. Comparison of factual and desired properties of known replacement methods leads us to the idea of how to improve their efficiency under changing technology reflected in decreasing operating and new asset costs. We introduce new modifications of the economic life and two-cycle variable-horizon methods by correcting their capital recovery factor. Next, we demonstrate that the modified methods deliver solutions equal or close to the infinite-horizon replacement under technological change
Preparing industry-ready analysts in the classroom: A module injection approach
No full textThe changes in the IT industry have diversified the role of an analyst. Analysts play an influential role in Information System Development (ISD) projects. Previous research indicates that the skill requirements of an analyst are both behavioral and knowledge based. Even though behavioral skills are critical, IS curriculum has typically focused on technological and domain knowledge skills. This research suggests an important focus of IS education should be at providing students with means to hone behavioral skills critical for systems analysts. The paper proposes that such interventions could be achieved in the form of behavioral module injection and demonstrates how such a module may be designed using existing theoretical perspectives from pedagogical research
Fabrication and evaluation of polycaprolactone/gelatin-based electrospun nanofibers with antibacterial properties
No full textNanofibrous scaffolds were fabricated through blending of a synthetic polymer, polycaprolactone (PCL), and a natural polymer, gelatin (GE), using an electrospinning technique. Processing and solution parameters were optimized to determine the suitable properties of PCL/GE-based nanofibers. Several characterizations were conducted to determine surface morphology by scanning electron microscopy (SEM), wettability using water contact angle measurement, and chemical bonding analysis using attenuated total reflectance (ATR) of PCL/GE-based nanofibers. Experimental results showed that 14% (w/v) PCL/GE with a flow rate of 0.5 mL/h and 18 kV demonstrated suitable properties. This nanofiber was then further investigated for its in vitro degradation, drug loading (using a model drug, tetracycline hydrochloride), and antibacterial testing (using zone inhibition method)
