Resin Distribution in Medium Density Fiberboard. Quantification of UF Resin Distribution on Blowline-and Dry-Blended MDF Fiber and Panels

A novel technique has been developed for visualizing urea formaldehyde (UF) resin distribution on fibers and within MDF panels. A fluorescent label was chemically bound to the resin, and digital images of resinated fiber, generated via confocal laser scanning microscopy (CLSM), were analyzed. Results indicate that this technique can be used to quantify UF resin coverage and distribution as well as provide information on resin film thickness on MDF fiber before pressing and in panels. The technique can distinguish between different methods of resination and was employed to determine that these processes can result in different surface coverages of UF resin on MDF fiber. Resin injected at the end of the blowline gave significantly less resin coverage of fiber than that which was injected at the start of the blowline. UF resin droplets were also relatively thicker and less dispersed when injected at the end of the blowline. Visualization of UF resin also illustrated resin distribution changes upon pressing of fiber particularly in the presence of wax. This result has important implications for future studies targeting optimization of resin deposition, since the droplet size distribution, as applied to the fiber, may not correspond to the droplet size distribution of resin in the panel

Optimal control of impulsive switched systems with minimum subsystem durations

This paper presents a new computational approach for solving optimal control problems governed by impulsive switched systems. Such systems consist of multiple subsystems operating in succession, with possible instantaneous state jumps occurring when the system switches from one subsystem to another. The control variables are the subsystem durations and a set of system parameters influencing the state jumps. In contrast with most other papers on the control of impulsive switched systems, we do not require every potential subsystem to be active during the time horizon (it may be optimal to delete certain subsystems, especially when the optimal number of switches is unknown). However, any active subsystem must be active for a minimum non-negligible duration of time. This restriction leads to a disjoint feasible region for the subsystem durations. The problem of choosing the subsystem durations and the system parameters to minimize a given cost function is a non-standard optimal control problem that cannot be solved using conventional techniques. By combining a time-scaling transformation and an exact penalty method, we develop a computational algorithm for solving this problem. We then demonstrate the effectiveness of this algorithm by considering a numerical example on the optimization of shrimp harvesting operations

An evaluation of methods used to assess fat cover in live cattle

[Summary]: Five methods of assessing subcutaneous fat cover were compared using male and female Bos indicus - Bos taurus beef cattle. None of the methods was able to accurately predict fat depth. The ESTD FAT technique has the greatest potential because it requires minimal handling. Use of the TRANS site may assist to improve accuracy with the ESTD FAT technique

A tactile method modified to assess the finish of beef cattle in marketable condition in north Queensland

Three methods of assessing the fat finish of marketable beef cattle were compared using Bos indicus crossbred cattle. The methods were: the Queensland Livestock Market Reporting Service, the National Beef Recording Scheme and a modified tactile method (MT) of the Meat and Livestock Commission. None of the three methods was able to predict accurately the fat depth at the 13th rib of the carcass. The highest correlation between finish score and fat depth was r = 0.568 for one operator using the MT method. However, wehn data from the MT method were examined it was found that mean fat depth at the 13th rib increased (P<0.05) with increasing finish score in two of the three liveweight categories studied. It is suggested that scoring individual animals on finish is no more accurate than weighing and allocating them to finish categories on the basis of liveweight

A neighboring extremal solution for an optimal switched impulsive control problem

This paper presents a neighboring extremal solution for a class of optimal switched impulsive control problems with perturbations in the initial state, terminal condition and system's parameters. The sequence of mode's switching is pre-specified, and the decision variables, i.e. the switching times and parameters of the system involved, have inequality constraints. It is assumed that the active status of these constraints is unchanged with the perturbations. We derive this solution by expanding the necessary conditions for optimality to first-order and then solving the resulting multiple-point boundary-value problem by the backward sweep technique. Numerical simulations are presented to illustrate this solution method

Control parameterization for optimal control problems with continuous inequality constraints: New convergence results

Control parameterization is a powerful numerical technique for solving optimal control problems with general nonlinear constraints. The main idea of control parameterization is to discretize the control space by approximating the control by a piecewise-constant or piecewise-linear function, thereby yielding an approximate nonlinear programming problem. This approximate problem can then be solved using standard gradient-based optimization techniques. In this paper, we consider the control parameterization method for a class of optimal control problems in which the admissible controls are functions of bounded variation and the state and control are subject to continuous inequality constraints. We show that control parameterization generates a sequence of suboptimal controls whose costs converge to the true optimal cost. This result has previously only been proved for the case when the admissible controls are restricted to piecewise continuous functions

Is dietary zinc protective for type 2 diabetes? Results from the Australian longitudinal study on women's health

Background: Animal studies have shown that zinc intake has protective effects against type 2 diabetes, but few studies have been conducted to examine this relationship in humans. The aim of this study is to investigate if dietary zinc is associated with risk of type 2 diabetes in a longitudinal study of mid-age Australian women. Methods: Data were collected from a cohort of women aged 45-50 years at baseline, participating in the Australian Longitudinal Study on Women's Health. A validated food frequency questionnaire was used to assess dietary intake and other nutrients. Predictors of 6-year incidence of type 2 diabetes were examined using multivariable logistic regression. Results: From 8921 participants, 333 incident cases of type 2 diabetes were identified over 6 years of follow-up. After adjustment for dietary and non-dietary factors, the highest quintile dietary zinc intake had almost half the odds of developing type 2 diabetes (OR = 0.50, 95% C.I. 0.32-0.77) compared with the lowest quintile. Similar findings were observed for the zinc/iron ratio; the highest quintile had half the odds of developing type 2 diabetes (OR = 0.50, 95% C.I 0.30-0.83) after multivariable adjustment of covariates. Conclusions: Higher total dietary zinc intake and high zinc/iron ratio are associated with lower risk of type 2 diabetes in women. This finding is a positive step towards further research to determine if zinc supplementation may reduce the risk of developing type 2 diabetes. © 2013 Vashum et al.; licensee BioMed Central Ltd

Optimal control strategies for tuberculosis treatment: a case study in Angola

We apply optimal control theory to a tuberculosis model given by a system of ordinary differential equations. Optimal control strategies are proposed to minimize the cost of interventions. Numerical simulations are given using data from Angola.Comment: This is a preprint of a paper whose final and definite form will appear in the international journal Numerical Algebra, Control and Optimization (NACO). Paper accepted for publication 15-March-201