On Stability of Constrained Receding Horizon Control with Finite Terminal Weighting Matrix

In this paper, a new stabilizing receding horizon control, based on a finite input and state horizon cost with a finite terminal weighting matrix, is proposed for time-varying discrete linear systems with constraints. We propose matrix inequality conditions on the terminal weighting matrix under which closed-loop stability is guaranteed for both cases of unconstrained and constrained systems with input and state constraints. We show that such a terminal weighting matrix can be obtained by solving a linear matrix inequality (LMI). In the case of constrained time-invariant systems, an artificial invariant ellipsoid constraint is introduced in order to relax the conventional terminal equality constraint and to handle constraints. Using the invariant ellipsoid constraints, a feasibility condition of the optimization problem is presented and a region of attraction is characterized for constrained systems with the proposed receding horizon control.     

Plasma density measurement and downstream etching of silicon and silicon oxide in Ar/NF3 mixture remote plasma source

In this study, plasma density measurements were performed near the plume region of the remote plasma source (RPS) in Ar/ NF₃ gas mixtures using a microwave cutoff probe. The measured plasma density is in the range of 10 ¹⁰ –10 ¹¹ cm ⁻³ in the discharge conditions with RPS powers of 2–4 kW and gas pressures of 0.87–4 Torr. The plasma density decreased with increasing gas pressures and RPS powers under various Ar/ NF₃ mixing ratios. This decrease in the plasma density measured at the fixed measurement position (plume region) can be understood by the reduction of the electron energy relaxation length with increases in the gas pressures and mixing ratio of NF₃/(Ar / NF₃). We also performed downstream etching of silicon and silicon oxide films in this system. The etch rate of the silicon films significantly increases while the silicon oxide is slightly etched with the gas pressures and powers. It was also found that the etch rate strongly depends on the wafer position on the processing chamber electrode, and that the etch selectivity reached 96–131 in the discharge conditions of RF powers (3730–4180 W) and gas pressures (3.6–4 Torr).     

Improving Detection of Vibrio vulnificus in Octopus variabilis by PCR

PCR methods can detect foodborne pathogenic bacteria with simplicity, specificity and speed. In order to improve sensitivity and speed of PCR methods for detection of Vibrio vulnificus in small octopus homogenate, several media and culture conditions were compared. Modified brain heart infusion media containing 2% NaCl and adjusted to pH 8.0 and 30°C was most effective for enrichment of the bacteria. Procedures affecting the efficiency of template DNA extraction and target DNA amplification were also optimized. By these combined efforts, a PCR procedure capable of detecting V. vulnificus as low as 10 cells/mL within 10h was developed.     

Small signal modelling for the PWM series resonant converter

A discrete time domain modelling is presented for the pulse-width modulated series resonant converter (PWM-SRC) with a discontinuous current mode. This nonlinear system is linearized about its equilibrium state to obtain a linear discrete time model for the investigation of small signal performances such as the stability and transient response. The usefulness of this small signal model is verified by dynamic simulation.     

Effects of Electrical Stimulation and Hot Boning on Functional Characteristics of Preblended Beef Muscle in Model Systems

Thirty beef carcasses were used to determine the effects of electrical stimulation (ES) and hot boning on the emulsifying capacity (EC) and thermal emulsion stability (TES) of preblended Triceps brachii (TB) muscle (long head) from sides assigned to one of four treatments: (1) conventionally boned after chilling at 2–8°C until 48 hr postmortem (CB); (2) hot boned at 1 hr postmortem (HB); (3) ES during bleeding and conventionally boned at 48 hr postmortem (ESCB); and (4) ES during bleeding and hot boned at 1 hr postmortem (ESHB). HB preblended samples had greater EC and TES values than CB preblended samples in both nonstimulated (P < 0.05) and stimulated carcasses. When compared to nonstimulated sides, ES decreased (P < 0.05) these values in both ESHB and ESCB sides.     

EVALUATION OF A CHEMICAL MARKER FOR PROCESS LETHALITY MEASUREMENT AT HOC IN A CONTINUOUS FLOW HOLDING TUBE

Meat beads containing glucose precursor of a chemical marker and alginate beads containing spores of Bacillus stearothermophilus were prepared and subjected to steam heating at HOC for selected time intervals. Marker yields were related to spore survivor data and lethality values obtained from time-temperature data to generate calibration curves. Meat balls, fabricated with meat (marker precursor) and alginate (microbial spores) beads placed at the center, were heated at 110 ± 0.5C for selected time intervals (0–55 min) in a continuous flow holding tube. During the heat treatment, the panicles were held stationary in the holding tube while the carrier fluid (0.5% CMC solution) was circulated at 2.6 gallons per min. Transient time-temperature responses of the particles were recorded at bead locations during test runs. All treated samples were analyzed for marker yield as well as spore survivors. Using the calibration curves and marker yield data under test conditions, the corresponding spore count reduction and accumulated lethalities were computed. Lethalities and spore count reductions calculated from marker yield data showed good correlations with those obtained from the experiment. The results indicate that the chemical marker has good potential to provide data on accumulated lethality and spore count reductions. Prior to extension of this approach to aseptic processing conditions, additional kinetic data on spore destruction and marker formation should be gathered at temperatures applicable to these processes.     

High-intensity laser-driven particle and electromagnetic wave sources for science, industry, and medicine

We simultaneously observed both the fast proton generation and terahertz (THz) radiation in the laser pulse interaction with a thin-foil target.The maximum proton energy of ～2.3 MeV and an intense THz radiation were observed at the pulse duration of ～30fs.We also measured the proton beam and UV harmonics from a thin-foil target by changing the laser pulse duration.In the case of the ～500 fs, peaks of UV harmonics up to fourth order appeared.This unique combination of the multiple beams will provide useful applications such as pump-probe experiments.     

DIRECT NUMERICAL SIMULATIONS OF THE DYNAMICS OF PARTICLES WITH ARBITRARY SHAPES IN SHEAR FLOWS

A fluid-structure interaction method based on the arbitrary Lagrangian-Eulerian method and a dynamic mesh method was developed to simulate the dynamics of a rigid particle in shear flows. In the method, the governing equations for the fluid flow and particle motion were sequentially solved in a two-way coupling fashion. The mesh system was deformed or re-meshed by the dynamic mesh method. The method was employed to simulate the dynamics of a single particle suspended in a flow channel and the dynamics of the particle were studied. The simulation results show that the angular velocity is not only a function of the inclination angle, is but also influenced by the aspect ratio yielding a hysteresis, while the angular velocity obtained from the Keller-Scalak model is a function only of the inclination angle and does not show a hysteresis. The present simulations clearly demonstrate that the Fluid-Structure Interaction (FSI) module is very stable, accurate and robust.