Hybrid Inclusions Research Articles

Two sequential fractional hybrid differential inclusions

The main objective of this paper is to concern with a new category of the sequential hybrid inclusion boundary value problem with three-point integro-derivative boundary conditions. In this direction, we employ various novel analytical techniques based on α-ψ-contractive mappings, endpoints, and the fixed points of the product operators to obtain the main results. Finally, we provide two examples to illustrate our main results.

On a hybrid inclusion problem via hybrid boundary value conditions

In this manuscript, the existence of solutions for a novel category of the fractional differential equation of hybrid type with hybrid boundary value conditions is studied. Also, we review the existence result for its related hybrid inclusion problem with hybrid conditions. In the end of the paper, two illustrative examples are given to demonstrate the consistency to our key results.

On fractional hybrid and non-hybrid multi-term integro-differential inclusions with three-point integral hybrid boundary conditions

In this paper, we investigate the existence of solutions for two nonlinear fractional multi-term integro-differential inclusions in two hybrid and non-hybrid versions. The boundary value conditions are in the form of three-point integral hybrid conditions. In this way, we define a new operator based on the integral solution of the given boundary value inclusion problem and then we use assumptions of a Dhage’s fixed point result for this fractional operator in the hybrid case. Also, the approximate endpoint property is applied for the corresponding set-valued maps in the non-hybrid case. Finally, we provide two examples to illustrate our main results.

Molecular Design and Synthesis of Ivermectin Hybrids Targeting Hepatic and Erythrocytic Stages of Plasmodium Parasites.

Ivermectin is a powerful endectocide, which reduces the incidence of vector-borne diseases. Besides its strong insecticidal effect on mosquito vectors of the disease, ivermectin inhibits Plasmodium falciparum sporogonic and blood stage development and impairs Plasmodium berghei development inside hepatocytes, both in vitro and in vivo. Herein, we present the first report on structural modification of ivermectin to produce dual-action molecular hybrids with good structure-dependent in vitro activity against both the hepatic and erythrocytic stages of P. berghei and P. falciparum infection, suggesting inclusion of ivermectin antimalarial hybrids in malaria control strategies. The most active hybrid displayed over threefold and 10-fold higher in vitro activity than ivermectin against hepatic and blood stage infections, respectively. Although an overwhelming insecticidal effect against Anopheles stephensi mosquitoes in laboratory conditions was not noticed, in silico docking analysis supports allosteric binding to glutamate-gated chloride channels similar to ivermectin.

Single and dual effects of magnesia and alumina nano-particles on strength and drying shrinkage of alkali activated slag

High drying shrinkage is considered as one of the main drawbacks which hinder the mass production of alkali activated slag (AAS). The formation of expansive phases was found to be the dominant factor for drying shrinkage reduction in sodium silicate-activated system. This work aims at studying single and synergistic effects of the prepared nano-magnesia (NM) and -alumina (NA) on compressive strength and drying shrinkage of AAS. A preliminary study revealed that the NM has a positive impact on the early age’s compressive strength of AAS; meanwhile NA had an opposite effect. Complementary, the drying shrinkage of AAS-NM significantly decreases with the increase of NM-content. Comparing with reference sample, the hybrid inclusion of 1 wt% NM and 1 wt% NA resulted in a significant drying shrinkage reduction and considerable compressive strength increment. The main reason behind this effect is the synergistic formation of calcium silicate hydrate and calcium aluminosilicate hydrate in parallel with expansive hydrotalcite and strätlingite phases as they have a potential effect on the performance of AAS including the retardation of water evaporation, reduction of pore volume, and drying shrinkage. This makes AAS-NM-NA composite can be beneficially used as a binder in the production of structural concrete with high durability.

Production and characterization of an advanced AA6061-Graphene-TiB2 hybrid surface nanocomposite by multi-pass friction stir processing

In this study, by the implementation of multi-pass friction stir processing (FSP) an advanced AA6061-Graphene-TiB2 hybrid surface nanocomposite is produced in contrast to the AA6061-Graphene and AA6061-TiB2 single composites. Effects of micro-sized TiB2 (10-30 wt%) and nano-sized graphene (0.5-2 wt%) particles on the microstructure and mechanical property of aluminum alloy are investigated. Moderate chemical composition as ~20 wt% TiB2 and 1 wt% graphene for the hybrid nanocomposite system yielded the best combinations of mechanical property overcome the wear-strength trade-off. Such optimum incorporation of hybrid inclusions mixture led a hardness increasing up to about two times higher, a yield strength improvement up to ~225 MPa (~300% increasing ratio), and an elongation loss down to ~9%. A considerable reduction in the coefficient of friction ~23% is revealed with the dominant contribution of sliding wear fractographic features on the worn-out fracture surface due to the presence of graphene in the nanocomposite structure acting as the lubricant agent.

Genetically informed captive breeding of hybrids of an extinct species of Galapagos tortoise.

Hybridization poses a major challenge for species conservation because it threatens both genetic integrity and adaptive potential. Yet, hybridization can occasionally offer unprecedented opportunity for species recovery if the genome of an extinct taxon is present among living hybrids such that selective breeding could recapture it. We explored the design elements for establishing a captive-breeding program for Galapagos tortoises (Chelonoidis spp.) built around individuals with admixed ancestry involving an extinct species. The target individuals were hybrids between the extinct species from Floreana Island, C. niger, and an extant species, C. becki, which were recently found in the endemic range of C. becki, from Wolf Volcano on Isabela Island. We combined genotypic data from 35 tortoises with high ancestry from C. niger with forward-in-time simulations to explore captive breeding strategies that maximized overall genetic diversity and ancestry from C. niger while accommodating resource constraints, species biology, and the urgency to return tortoises to Floreana Island for facilitating ecosystem restoration. Overall genetic diversity was maximized when in the simulation tortoises were organized in relatively small breeding groups. Substantial amounts of the C. niger genome were captured despite limited resources available for selectively breeding tortoises in captivity. Genetic diversity was maximized when captive-bred offspring were released to the wild rather than being used as additional breeders. Our results provide genetic-based and practical guidance on the inclusion of hybrids with genomic representation from extinct taxa into species restoration programs and informs the ongoing debate on the value of hybrids in biodiversity conservation.

Genetic architecture of barley (Hordeum vulgare L.) genotypes for grain yield and yield attributing traits

Combining ability for yield and its related traits was studied in 13 barley genotypes and their F1 progenies obtained through line x tester mating design. Significant differences for most of the traits in both gca and sca components revealed the importance of both additive and non-additive gene actions with the predominant effect of nonadditive gene action. Among parents, lines DWRB 134, BH 902 and RD2919 emerged as good general combiner for yield and importantcomponent traits whereas DWRUB 52 was identified as the best tester. Hence, these are considered as good general combiners for deriving desirable transgressive segregants for specific characters. However, line BH 902 emerged as good general combiner for maximum number of yield contributing traits i.e., peduncle length, spike length, awn length, productive tillers per plant, flag leaf area, number of grains per spike, weight of spike, 1000 grain weight, biological yield per plant and grain yield per plant. Among thirty crosses, seven displayed significant and positive specific combining ability (sca) effects for grain yield. Out of these seven crosses, four hybrids viz., BH 976 × RD 2849, DWRB 134 × DWRUB 52, BH 965 × DWRUB 52, BH 902 ×DWRB 101, were identified as the best promising combinations having good specific combining ability effects along with high per se performance for grain yield as well as other attributing characters in desired direction. The estimates of general combining ability (gca) effects as a whole suggested that if most of the characters are to be improved, inclusion of F1 hybrids showing high sca in crop improvement program and parents with good gca, into multiple crosses, bi-parental mating, and diallel selective mating could prove a worthwhile approach for tangible advancementof grain yield in barley. Doi.org/10.25174/2249-4065/2018/83148

Interfacial interactions, crystallization and molecular mobility in nanocomposites of Poly(lactic acid) filled with new hybrid inclusions based on graphene oxide and silica nanoparticles

Polymer composites based on poly(lactic acid) (PLA) and three fillers, graphene oxide (GO), silica nanoparticles, and a nanohybrid consisting of silica doped GO, were prepared and investigated. A combination of complimentary techniques, namely thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), polarized light microscopy (PLM), differential scanning calorimetry (DSC), and broadband dielectric spectroscopy (BDS), were employed to study the polymer-filler interaction, crystallization and molecular mobility. For the low filler content of 1 wt%, all inclusions act as nucleating agents, increasing the rate of PLA crystallization. Among all fillers, including the mixture of pristine silica and GO, the nanohybrid imposes the stronger effects on crystallization rate, the latter being highly desirable in industrial processing of PLA. The crystalline fraction (∼30%) was found to be the dominant factor in molecular mobility, is agreement with previous investigations on PLA based systems. Based on the degree of polymer/filler interaction (FTIR) and the suppression in calorimetric/dielectric strength of the glass transition (DSC/BDS), the interfacial rigid amorphous fraction (RAF) could be estimated. Interestingly, RAF exhibits its largest value for the composite based on the hybrid filler, in qualitative agreement between the three techniques. The latter fraction, representative of the polymer adsorption onto the nanofillers, is considered important within many applications (thin polymeric films, polymer nanocomposites, etc), furthermore, it is widely believed that RAF dominates the observed improvements of the properties in the nanocomposites.

Global Optimization on the Sphere: A Stochastic Hybrid Systems Approach

We cast a stochastic, hybrid algorithm for global optimization on the unit sphere in the framework of stochastic hybrid inclusions. The algorithm contains two hybrid features. First, it includes hysteresis switching between two coordinate charts in order to be able to fully explore the sphere by flowing without encountering singularities in the flow vector field. Secondly, it combines gradient flow with jumps that aim to escape singular points of the function to minimize, other than those singular points corresponding to global minima. The algorithm is stochastic because the jumps involve random probing on the sphere. Solutions are not unique because the jumps are governed by a set-valued mapping, i.e., an inclusion. Regarding the coordinate charts employed, we discuss both the use of spherical coordinates as well as stereographic projection. By using the framework of stochastic hybrid inclusions, we provide a detailed stability characterization of the optimization algorithm. In particular, we establish uniform global asymptotic stability in probability of the set of global minimizers for arbitrary continuously differentiable functions defined on the sphere.

Finite time stability of sets for hybrid dynamical systems

Notions and tools for finite time stability of closed sets for hybrid dynamical systems modeled as hybrid inclusions are introduced. Finite time stability of a closed set is defined as the following two properties: Lyapunov stability, namely, the property that solutions that start close to the set stay close to it, and finite time convergence. In the latter property, the amount of time required to converge to the set of interest is captured by a settling-time function that depends on hybrid time, namely, the time elapsed during flows and the number of jumps (or events) of the hybrid system. Various sufficient conditions for such properties to hold for a given closed set are established. Conditions involving Lyapunov-like functions that strictly decrease during flows, that strictly decrease during jumps, and that strictly decrease along both regimes are proposed — these functions are only required to be locally Lipschitz. A link between (non-finite time) asymptotic stability and the proposed notion is also established. In addition, sufficient conditions for finite time attractivity involving properties at jumps of the system, the second derivative of a Lyapunov-like function, and a property of nested sets are provided. Throughout the paper, examples exercise the results. In addition, an application to finite time parameter estimation is provided and results are applied to it.

Forward Invariance of Sets for Hybrid Dynamical Systems (Part I)

In this paper, tools to study forward invariance properties with robustness to disturbances, referred to as robust forward invariance , are proposed for hybrid dynamical systems modeled as hybrid inclusions. Hybrid inclusions are given in terms of differential and difference inclusions with state and disturbance constraints, for whose definition only four objects are required. The proposed robust forward invariance notions allow for the diverse type of solutions to such systems (with and without disturbances), including solutions that have persistent flows and jumps, that are Zeno, and that stop to exist after finite amount of (hybrid) time. Sufficient conditions for sets to enjoy such properties are presented. These conditions are given in terms of the objects defining the hybrid inclusions and the set to be rendered robust forward invariant. In addition, as special cases, these conditions are exploited to state results on nominal forward invariance for hybrid systems without disturbances. Furthermore, results that provide conditions to render the sublevel sets of Lyapunov-like functions forward invariant are established. Analysis of a controlled inverter system is presented as an application of our results. Academic examples are given throughout this paper to illustrate the main ideas.

Synergistic Effect of Nitrogen and Refractory Material on TiN Formation and Equiaxed Grain Structure of Ferritic Stainless Steel

The effect of nitrogen content on the formation of an equiaxed solidification structure of Fe-16Cr steel was investigated. Moreover, two different kinds of refractory materials, i.e., alumina and magnesia, were employed to control the type of oxide inclusion. The characteristics of TiN(-oxide) inclusions were quantitatively analyzed in both molten steel and solidified samples. When the melting was carried out in the alumina refractory, the grain size continuously decreased with increasing nitrogen content. However, a minimum grain size was observed at a specific nitrogen content (approx. 150 ppm) when the steel was melted in the magnesia refractory. Most of the single TiN particles had a cuboidal shape and fine irregularly shaped particles were located along the grain boundary due to the microsegregation of Ti at the grain boundary during solidification. The type of TiN-oxide hybrid inclusion was strongly affected by the refractory material where Al2O3-TiN and MgAl2O4-TiN hybrid-type inclusions were obtained in the alumina and magnesia refractory experiments, respectively. The formation of oxide inclusions was well predicted by thermochemical computations and it was commonly found that oxide particles were initially formed, followed by the nucleation and growth of TiN. When the nitrogen content increased, the number density of TiN linearly increased in the alumina refractory experiments. However, the number of TiN exhibits a maximum at about [N] = 150 ppm, at which a minimum grain size was obtained in the magnesia refractory experiments. Therefore, the larger the number density of TiN, the smaller the primary grain size after solidification. The number density of TiN in the steel melted in the magnesia refractory was greater than that in the steel melted in the alumina refractory at given Ti and N contents, which was due to the lower planar lattice disregistry of MgAl2O4-TiN interface rather than that of Al2O3-TiN interface. When ∆TTiN (= difference between the TiN precipitation temperature and the liquidus of the steel) was 20 K to 40 K, the number density of effective TiN was maximized and thus, the grain size was minimized after solidification. Finally, although most of the TiN particles were smaller than 1 μm in the molten steel samples irrespective of the nitrogen content, TiN particles larger than 10 μm were observed in the solidified samples when the nitrogen content was greater than 150 ppm. The growth of TiN particles during melting and solidification was well predicted by the combinatorial simulation of the ‘Ostwald ripening model’ based on the Lifshitz–Slyozov–Wagner theory in conjunction with the ‘Diffusion controlled model’ using Ohnaka’s microsegregation equation.

Solvability of coupled systems of hybrid fractional differential equations and inclusions

In this paper, we investigate the boundary value problems of the coupled systems of hybrid fractional differential equations and inclusions with coupled boundary conditions involving Caputo fractional derivative. By means of Leary-Schauder alternative and Bohnenblust-Karlin fixed point theorem, some results concerning the existence of solutions are obtained. At the same time, we also give the relationship between solutions and upper and lower solutions. Finally, examples are presented to illustrate our main results.

Pointwise Asymptotic Stability in a Hybrid System and Well-Posed Behavior Beyond Zeno

Hybrid dynamical systems, modeled by hybrid inclusions---a combination of differential equations or inclusions, of difference equations or inclusions, and of constraints on the resulting motions---...

Estimation and optimisation of effective thermal conductivity for polymer matrix composites with hybrid inclusions

Composites with hybrid inclusions have shown remarkable thermal conductivity enhancement over composites with a single type of inclusion. However, to achieve maximum thermal conductivity enhancement, the optimum ratio of inclusions in the hybrid mix needs to be determined. In this communication, an effective medium theory based model for the estimation of effective thermal conductivity of composites with hybrid inclusions is presented. The proposed model accurately captures the synergic effect of hybrid inclusions within the composite and can be used to optimise the filler ratio in the hybrid mix. The model has been validated against several published experimental results and is found to be in good agreement with them. Parametric studies have also been carried out to study the effect of material and model parameters on the optimum ratio of hybrid inclusions.

Inclusion characteristics and microstructure properties under different cooling conditions in steel with nanoparticles addition

ABSTRACTIn the present study, the experimental steel containing nanoparticles was manufactured and then cooled to room temperature under different cooling rates. The differences on the inclusion characteristics and microstructure morphologies between the original steel and experimental steel were compared. The results revealed that the majority of reaction products in the experimental steel were Al2O3–MgO-bearing hybrid inclusions. These inclusions under brine quenching, and water quenching had large potential for inducing intra-granular acicular ferrites (IAF). Hence the microstructure in the experimental steel mainly consisted of fine IAF. For the original steel, SiO2–MnO–MnS-based inclusions could hardly induce IAF, and the microstructure consisted of relatively larger intra-granular banded ferrites, and intra-granular polygonal ferrites. The differences on microstructure morphologies between the two steels had a correlation with the inclusion composition, and size. These were the primary factors to determine whether a particular type of inclusion could induce IAF effectively or not.

Solution Concepts and Analysis of Spatially Invariant Hybrid Systems: Exploring Zeno and beyond

Abstract: In this paper we consider hybrid systems, consisting of an infinite number of interconnected spatially invariant (identical) hybrid subsystems described using the hybrid inclusions framework. It can be shown that such interconnections can be very useful in, e.g., the modeling of interconnected networked subsystems that use packet-based communication for the exchange of information, including autonomously driving platoons of vehicles. Interestingly however, due to the infinite-dimensionality of the overall interconnected hybrid system, establishing proper definitions of solutions becomes a difficult task as standard solution concepts do not apply to the systems under study since Zeno behavior (an infinite number of jumps in a bounded time interval) is inevitable. Therefore, we introduce an alternative and natural solution concept for this class of systems, allowing solutions to be defined beyond Zeno points. In addition, based on this novel solution concept, we derive Lyapunov-based conditions for a specific, but relevant class of infinite-dimensional hybrid systems, as used for modeling, for instance, networked control systems, that guarantee UGAS (or UGES) or L p -stability of the overall interconnected system.

Addition of MgO Nanoparticles to Carbon Structural Steel and the Effect on Inclusion Characteristics and Microstructure

An innovative approach for pre-dispersing MgO nanoparticles with AlSi alloy nanoparticles was established, and the nanoparticles were dispersed well in carbon structural steel. After adding different mass fractions of MgO nanoparticles in steel, the majority of inclusions contained MgO·Al2O3 spinel and MgO-Al2O3-bearing hybrid inclusion, and these inclusions promoted acicular ferrite (AF) formation. With increasing amount of added nanoparticles, the average inclusion size increased from 0.90 to 1.50 μm and the inclusion size was considerably refined, but the ability of inclusions to induce AF was greatly declined. It was revealed that the inclusion size was the decisive factor influencing the inducing ability of inclusions for AF, which also got a solid support from the nucleation thermomechanical and dynamic analyses. When the mass fraction of MgO nanoparticles reached 0.05 pct, the proportion of AF in microstructure is relatively larger and the degree of interlocking of the AF within the microstructure was optimized. The ferrite grains also got refined and the average grain size decreased by more than 94 pct compared with that of the original steel.

POSS-Containing Jacketed Polymer: Hybrid Inclusion Complex with Hierarchically Ordered Structures at Sub-10 nm and Angstrom Length Scales

A series of organic–inorganic hybrid polymers, PnPOSS (n = 6, 10, which is the number of carbon atoms in the flexible alkyl spacers), containing a mesogen-jacketed liquid crystalline polymer (MJLCP) as the main chain and a crystalline nanobuilding block, polyhedral oligomeric silsesquioxane (POSS), in the side chains were designed and synthesized for constructing a hybrid inclusion complex. The phase structures and phase transitions of PnPOSS were investigated by differential scanning calorimetry, polarized light microscopy, wide-angle X-ray diffraction, small-angle X-ray scattering, and high-resolution transmission electron microscopy. With the competitive self-assemblies of the two covalently connected building blocks, namely MJLCP and POSS moieties, PnPOSS shows various phase structures including a sub-10 nm hexagonal columnar (Colh) or columnar nematic liquid crystalline phase, an angstrom rhombohedral crystalline (KR) phase, and a hierarchically ordered phase with Colh and KR coexisting. This work provides a new approach for the design and synthesis of hybrid inclusion materials.