Simulations between Three Types of Networks of Splicing Processors

Networks of splicing processors (NSP for short) embody a subcategory among the new computational models inspired by natural phenomena with theoretical potential to handle unsolvable problems efficiently. Current literature considers three variants in the context of networks managed by random-context filters. Despite the divergences on system complexity and control degree over the filters, the three variants were proved to hold the same computational power through the simulations of two computationally complete systems: Turing machines and 2-tag systems. However, the conversion between the three models by means of a Turing machine is unattainable because of the huge computational costs incurred. This research paper addresses this issue with the proposal of direct and efficient simulations between the aforementioned paradigms. The information about the nodes and edges (i.e., splicing rules, random-context filters, and connections between nodes) composing any network of splicing processors belonging to one of the three categories is used to design equivalent networks working under the other two models. We demonstrate that these new networks are able to replicate any computational step performed by the original network in a constant number of computational steps and, consequently, we prove that any outcome achieved by the original architecture can be accomplished by the constructed architectures without worsening the time complexity.

Characterization of Methacrylate-Based Resins Containing Methacryl-Polyhedral Oligomeric Silsesquioxanes (MA-POSS-8)

The use of functionalized dental adhesives that might prevent degradation of the dentin hybrid layer has been proposed. The aim of the study was to characterize the physicochemical properties and the potential to induce mineral precipitation of methacrylate-based resins containing methacryl-functionalized polyhedral oligomeric silsesquioxane (MA-POSS-8). In total, six different compositions of resins based on bisphenol A glycerolate dimethacrylate (BisGMA, 40 to 60 wt.%), triethylene glycol dimethacrylate (TEGDMA, 5 to 35 wt.%) and 2-hydroxyethyl methacrylate (HEMA, 25 or 35 wt.%) were prepared and infiltrated with 5 wt.% MA-POSS-8. Unfilled resins served as control. Degree of conversion, viscosity, Martens hardness, indentation modulus, water sorption, and sol fraction were investigated. Polymerized specimens were examined by SEM/EDX for the presence of Ca/P precipitates after immersion in artificial saliva for 28 days at 37 °C. Statistical analysis was performed with two-way ANOVA and Tukey’s post-hoc test (p < 0.05). The degree of conversion ranged from 55.0 to 59.8% and was not affected by the addition of MA-POSS-8. Viscosity ranged from 60.0 to 422.3 mPa*s and was not affected by MA-POSS-8 except for one methacrylate-based resin with 60 wt.% BisGMA. Martens hardness and indentation modulus ranged from 161.3 to 138.1 N/mm2 and 4.2 to 3.9 kN/mm2 and were affected by MA-POSS-8 in only one resin (50 wt.% BisGMA, 25 wt.% TEGDMA, 25 wt.% HEMA). Water sorption was not affected by MA-POSS-8; sol fraction was below the detection limit. Formation of Ca/P precipitates was observed on all specimens of test and control groups. Material properties were not affected adversely by MA-POSS-8 except for slight differences in Martens hardness, indention modulus, viscosity in some groups. However, bioactive properties could not be improved by MA-POSS-8.

Super-Twisting Sliding Mode Control Law Design for Attitude Tracking Task of a Spacecraft via Reaction Wheels

The attitude control has been recognized as one of the most important research topics for spacecraft. If the desired attitude trajectory cannot be tracked precisely, it may cause mission failures. In the real space mission environment, the unknown external perturbations, for example, atmospheric drag and solar radiation, should be taken into consideration. Such external perturbations could deviate the precision of the spacecraft orientation and thereby lead to a mission failure. Therefore, in this paper, a quaternion-based super-twisting sliding mode robust control law for the spacecraft attitude tracking is developed. The finite time stability based on the formulation of the linear matrix inequality (LMI) is also provided. To avoid losing the control degree of freedom due to the certain actuator fault, a redundant reaction wheels configuration is adopted. The actuators distribution associated force distribution matrix (FDM) is analyzed in detail. Finally, the reference tangent-normal-binormal (TNB) command generation strategy is implemented for simulating the scenario of the space mission. Finally, the simulation results reveal that the spacecraft can achieve the desired attitude trajectory tracking demands in the presence of the time-varying external disturbances.

Fine Fabrication and Optical Waveguide Characteristics of Hexagonal tris(8-hydroxyquinoline)aluminum(Ⅲ) (Alq3) Crystal

Herein, we reported on the precise growth and optical waveguide characteristics of hexagonal tris(8-hydroxyquinoline)aluminum(Ⅲ) (Alq3) micro-crystals (MCs). The hexagonal Alq3 MCs were prepared using surfactant-assisted assembly growth with the help of cetyltrimethylammoniumbromide (CTAB), in which the crystallization occurred as a result of molecular assembly and packing. Also, we adjusted the molar ratio of Alq3 and CTAB for the control degree of crystallization. The formation and structure of Alq3 MCs were investigated using field-emission scanning electron microscopy and X-ray diffraction pattern experiments, respectively. The solid-state laser confocal microscope-photoluminescence spectra and charge-coupled device images for the Alq3 MCs were measured to study the luminescence efficiency and colors, respectively. The optical waveguide performance of the hexagonal Alq3 MCs was measured for each side direction. According to our results, crystalline Alq3 micro-crystals are promising materials for application to the development of optical communication devices.