Permanence and stability of an Ivlev-type predator–prey system with impulsive control strategies

In this paper, we study a predator–prey system with an Ivlev-type functional response and impulsive control strategies containing a biological control (periodic impulsive immigration of the predator) and a chemical control (periodic pesticide spraying) with the same period, but not simultaneously. We find conditions for the local stability of the prey-free periodic solution by applying the Floquet theory of an impulsive differential equation and small amplitude perturbation techniques to the system. In addition, it is shown that the system is permanent under some conditions by using comparison results of impulsive differential inequalities. Moreover, we add a forcing term into the prey population’s intrinsic growth rate and find the conditions for the stability and for the permanence of this system.     

Particle-yield modification in jetlike azimuthal dihadron correlations in Pb-Pb collisions at √s(NN)=2.76 TeV

The yield of charged particles associated with high-p(t) trigger particles (83 GeV/c on the away side drops to about 60% of that observed in pp collisions, while on the near side a moderate enhancement of 20%-30% is found.     

Temperature-dependent absorptance of painted aluminum, stainless steel 304, and titanium for 1.07 μm and 10.6 μm laser beams

We measured the temperature-dependent absorptance of metals (Al, Ti, SS304) for continuous beams from 1.07 μm fiber laser and 10.6 μm CO₂ laser using power sensors and infrared (IR) pyrometers. The absorptance measurements were repeated for metals with three different paint coatings. For measurements at elevated temperatures up to the melting point, integrating sphere is not practical since high temperature radiation from a heated target disturbs weak output from the sphere considerably. Our results provide how each metal, whether coated or uncoated, absorbs the infrared beams as temperature is elevated to a melting point. A polynomial approximation to the measured absorptance of each target is provided for modeling of the laser-metal interaction at elevated temperatures.     

An automatic processing technique for accurate surface form measurement

A single shot algorithm using a Fizeau interferometer was used to measure the form profile of a spherical smooth surface by means of fringe thinning process, which plays an important role in fringe patterns analysis. In this paper, an automatic processing technique based on the fringe thinning process is presented. The circular interference fringe pattern of the spherical smooth surface captured by the Fizeau interferometer was corrected by using the flat fielding method and then processed. Based on the fringe thinning and the assignment of the fringe orders, the information on the fringe feature was recovered automatically and the interference wavefront was reconstructed by the Zernike polynomial fitting method. The results were compared with the results measured by Bünnagel method, and the results were in good agreement. This means that the single shot algorithm is reliable, fast, and less sensitive to vibration and turbulence in surface form measurements. Simulation fringes with the ray tracing technique were obtained to match the practical fringes.     

Highly accurate film thickness measurement based on automatic fringe analysis

This paper describes an automated multiple-beam interferometry for measuring a calibrated step height of (27.00 ± 3.00) nm nominally. The fringes captured from the multiple-beam Fizeau–Tolansky interferometer were thinned by using a written program to obtain accurate measurement. We claim that multiple-beam interferometry based on automatic fringe thinning process can provide a real time solution for calibrating step heights precisely and with high accuracy. The uncertainty budget of the multiple-beam interferometry method due to incomplete parallelism of the incident beam and the inhomogeneity of the reflecting layers was calculated automatically with a written ray tracing program. The uncertainty budget in multiple-beam interferometry was estimated to be of the order of 3.00 nm.     

Preparation,structure, and photoluminescence properties of Ga2O3/SnO2 coaxial nanowires

Ga₂O₃/SnO₂ coaxial nanowires were synthesized by thermal evaporation of GaN powders and then atomic layer deposition of SnO₂. Transmission electron microscopy (TEM) and X‐ray diffraction (XRD) analysis results indicate that the Ga₂O₃ cores and the SnO₂ shells of the coaxial nanowires after thermal annealing are single crystals with monoclinic and simple orthorhombic structures, respectively, although the SnO₂ shells are amorphous before annealing. Our results also show that photoluminescence (PL) emission can be enhanced by thermal annealing in an H₂/N₂ atmosphere. EDX concentration profile suggests that the enhancement in the bluish green emission is due to the increase in the concentration of the Ga vacancies in the cores during the H₂/N₂ annealing. On the other hand, a red emission is newly formed while the bluish green emission is degraded by annealing in an oxygen or nitrogen atmosphere (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation and Characterization of Carbon Fibers from Lyocell Precursors Grafted with Polyacrylamide via Electron-Beam Irradiation

Carbon fibers, which act as reinforcements in many applications, are often obtained from polyacrylonitrile (PAN). However, their production is expensive and results in waste problems. Therefore, we focused on producing carbon fibers from lyocell, a cellulose-based material, and analyzed the effects of the process parameters on their mechanical properties and carbon yields. Lyocell was initially grafted with polyacrylamide (PAM) via electron-beam irradiation (EBI) and was subsequently stabilized and carbonized. Thermal analysis showed that PAM grafting increased the carbon yields to 20% at 1000 °C when compared to that of raw lyocell, which degraded completely at about 600 °C. Stabilization further increased this yield to 55%. The morphology of the produced carbon fibers was highly dependent on PAM concentration, with fibers obtained at concentrations ≤0.5 wt.% exhibiting clear, rigid, and round cross-sections with smooth surfaces, whereas fibers obtained from 2 and 4 wt.% showed peeling surfaces and attachment between individual fibers due to high viscosity of PAM. These features affected the mechanical properties of the fibers. In this study, carbon fibers of the highest tensile strength (1.39 GPa) were produced with 0.5 wt.% PAM, thereby establishing the feasibility of using EBI-induced PAM grafting on lyocell fabrics to produce high-performance carbon fibers with good yields.     

Influence of synthesis temperature on morphology and electrochemical performance of NiCo hydroxides for supercapacitor applications

Journal of Solid State Electrochemistry - In this work, the effects of hydrothermal growth temperature on the morphology and electrochemical characteristics of NiCo hydroxides were studied. The...