Breakthrough and Sulfate Conversion Analysis during Removal of Sulfur Dioxide by Calcium Oxide Sorbents

Sorption of sulfur dioxide (SO₂) was carried out on calcium‐based sorbents under dynamic conditions in a fixed bed. The experimental conditions were reaction temperature (700 to 1000°C), SO₂ concentration (1000‐10 000 ppm), sorbent particles size (1 to 2 mm) and the types of sorbents (hydroxide or carbonate). The sorption process was found to be effective at low concentration levels (less than 10 000 ppm) as the breakthrough time significantly decreased with increase in concentration. The maximum removal of SO₂ was observed at a reaction temperature of 950°C. The hydroxide‐based sorbents of relatively smaller particle size were found to exhibit superior sorption performance in terms of longer breakthrough time and higher sulfate conversion. A mathematical model developed, assuming a porous structure of the sorbent materials, attributed the low sulfation conversion during SO₂ sorption due to a pore diffusion mechanism.     

A Synthesis of Feedback and Feedforward Control for Process Improvement Under Stationary and Nonstationary Time Series Disturbance Models

Process adjustment strategy is an important part of the process improvement methods. The feedback control technique is used to compensate for the deviation of the output, and it has been intensively investigated. For continuous improvement and proactive strategies, feedback control has a delay and thus is not the ideal solution. In this article, motivated by a realistic manufacturing example, we propose the periodic shift disturbance models and investigate the feedforward control application from a new disturbance decomposition framework. We combine feedforward control with feedback control for maintaining the stability of the process and delivering products at target values. Then, we evaluate the performance of different control strategies for various disturbance models by using the output mean square error criterion. Sensitivity analysis of these control methods is made on different model parameter spaces, and robustness analysis for both model parameter and model structure misspecifications is presented. Two simulated examples show that the proposed control strategies can significantly reduce the variation of an evolving disturbance process. Copyright © 2014 John Wiley & Sons, Ltd.     

Thermal model of a cylindrically symmetric solar pond

A finite element heat transport program has been modified to model the thermal behavior for a cylindrically symmetric salt gradient polar pond of the Rabl-Nielsen type. In this model transient phenomena as well as steady state behavior can be studied. Results are presented for a model of the solar pond at the University of New Mexico and are compared with actual measurements.     

On a single server queue with two-stage heterogeneous service and deterministic server vacations

We analyse a single server queue with Poisson arrivals, two stages of heterogeneous service with different general (arbitrary) service time distributions and binomial schedule server vacations with deterministic (constant) vacation periods. After first-stage service the server must provide the second stage service. However, after the second stage service, he may take a vacation or may decide to stay on in the system. For convenience, we designate our model as M/G ₁, G ₂/D/1 queue. We obtain steady state probability generating function of the queue length for various states of the server. Results for some particular cases of interest such as M/E_{k 1} , E_{k 2} /D/1, M/M ₁, M ₂/D/1, M/E _k /D/1 and M/G ₁, G ₂/1 have been obtained from the main results and some known results including M/E_k /1 and M/G/1 have been derived as particular cases of our particular cases.     

Competing Effects of Radio Frequency Fields on Carbon Nanotube/Resin Systems: Alignment versus Heating

This work shows that radio-frequency (RF) fields can simultaneously align carbon nanotubes (CNTs) dispersed in a resin and induce Joule heating to cure the resin. The timescales of alignment and curing using RF heating are numerically computed and compared at different field strengths in order to determine a temperature where alignment happens before the matrix crosslinks. Composites are experimentally fabricated at the desired target temperature and are optically analyzed and quantified; the CNT network is successfully aligned in the direction of the applied electric field. This methodology can be used to create composites where the local alignment can be varied across the sample. Composites fabricated using RF fields have higher electrical conductivity in the direction of the aligned CNTs than an oven-cured, randomly aligned sample. Also, RF-cured nanocomposites exhibit higher tensile strength and modulus in the direction of alignment compared to an oven-cured sample. Finally, it is further demonstrated how this methodology can be coupled with a direct ink writing additive manufacturing process to induce alignment in any desired direction, even orthogonal to the shear forces in the extrusion direction.     

Feeding responses ofChilo partellus (Swinhoe) (Lepidoptera: Pyralidae) larvae to sorghum plant phenolics and their analogs

Phagostimulatory responses of third-instar larvae ofChilo Partellus to phenolic components identified in an ethyl acetate extract of the leaf whorls of 3-week-old plants ofSorghum bicolor cultivar IS 18363 were studied in no-choice bioassays. The major components in the extract were identified as 4-hydroxybenzaldehyde and 4-hydroxybenzoic acid, with 4-hydroxy-3-methoxycinnamic acid, 3,4-dihydroxycinnamic acid, and 4-hydroxycinnamic acid present in minor amounts. All but 4-hydroxycinnamic acid were stimulatory at the doses tested. 4-Hydroxybenzaldehyde was more stimulatory than other potential biogenetic analogs. Hydroxybenzoic acids generally elicited greater feeding response than cinnamic acids, and the pattern of oxygen substitution in the benzene ring was related to bioactivity.     

Fast and stable bayesian image expansion using sparse edge priors.

Smoothness assumptions in traditional image expansion cause blurring of edges and other high-frequency content that can be perceptually disturbing. Previous edge-preserving approaches are either ad hoc, statistically untenable, or computationally unattractive. We propose a new edge-driven stochastic prior image model and obtain the maximum a posteriori (MAP) estimate under this model. The MAP estimate is computationally challenging since it involves the inversion of very large matrices. An efficient algorithm is presented for expansion by dyadic factors. The technique exploits diagonalization of convolutional operators under the Fourier transform, and the sparsity of our edge prior, to speed up processing. Visual and quantitative comparison of our technique with other popular methods demonstrates its potential and promise.     

Signal-to-noise ratio development for quality engineering

Dr. Taguchi developed the concept of signal-to-noise (SN) ratio in quality engineering to evaluate the performance of a system. The objective is to develop systems which are robust against noise factors. The SN ratio indicates the degree of the predictable performance of a product or process in the presence of noise factors. Parameter design of the Taguchi method optimizes the SN ratio in the domain of control factors, so that performance could be made insensitive to the noise factors in order to improve product quality. If the domain of the control factors is a continuous space, the problem is a non-linear programming problem. Usually, in practice, there are only a few available levels for the control factors. Thus, experimental design methods can be useful for such problems. The SN ratio for four cases of dynamic characteristic problems is developed in this paper. This paper also gives the method to compute SN ratios for both equispaced and non-equispaced intervals for levels of signal factors. Two examples are presented to illustrate the method.     

Assessment of protein quality by partial carcass analyses. Nitrogen retention in rats in relation to the nitrogen content in hind limbs

Dietary protein quality was measured in N balance experiments and compared with partial carcass analyses (hind limbs). The results obtained from 16 experiments with rats show that there is a highly significant positive correlation (r = 0.97) between N retained in 5 days and the N content in hind limbs.     

Reliability Analysis for Multistate Systems with Multistate Components

An important problem in reliability theory is to determine the reliability of a complex system given the reliabilities of its components. In real life, the system and its components can be found in a range of states varying from perfect functioning through various levels of performance degradation to complete failure. This paper presents some models and their applications, in terms of reliability analyses, to situations where the system can have a whole range of states and all its components can also have a wide range of multiple states. Properties of the system structure function and computation and approximation of system state probabilities and system reliability measures are given.