Explicit model predictive control of gas–liquid separation plant via orthogonal search tree partitioning

Solutions to constrained linear model predictive control (MPC) problems can be pre-computed off-line in an explicit form as a piecewise linear (PWL) state feedback defined on a polyhedral partition of the state space. This admits implementation at high sampling frequencies in real-time systems with high reliability and low software complexity. Recently, algorithms that determine an approximate explicit PWL state feedback solution by imposing an orthogonal search tree structure on the partition, have been developed, and it has been shown that they may offer computational advantages. This paper considers the application of an approximate approach to the design of an explicit model predictive controller for a two-input two-output laboratory gas–liquid separation plant, including experimental evaluation. The approximate explicit MPC controller achieves performance close to that of the conventional MPC, but requires only a fraction of the real-time computational machinery, thus leading to fast and reliable computations.     

Mechanical behavior of double-C60-end-capped poly(ethylene oxide)

Double-C₆₀-end-capped poly(ethylene oxide) (PEO) possesses good mechanical properties arising from a network-like structure due to the aggregation of C₆₀. The tensile strength is about 20 MPa, the elongation at break exceeds 640% and the fracture toughness is more than 110 MJ/m³. The material also possesses shape recovery ability. In contrast, single-C₆₀-end-capped PEO does not possess good mechanical properties.     

Miscibility and interactions in poly(methylthiomethyl methacrylate)/poly(vinyl alcohol) blends

Poly(methylthiomethyl methacrylate) (PMTMA) is miscible with poly(vinyl alcohol) (PVA) over the whole composition range as shown by the existence of a single glass transition temperature in each blend. The interaction between PMTMA and PVA was examined by Fourier transform infrared spectroscopy, solid-state nuclear magnetic resonance spectroscopy and X-ray photoelectron spectroscopy. The interactions mainly involve the hydroxyl groups of PVA and the thioether sulfur atoms of PMTMA, and the involvement of the carbonyl groups of PMTMA in interactions is not significant. The measurements of proton spin-lattice relaxation time reveal that PMTMA and PVA do not mix intimately on a scale of 1-3 nm, but are miscible on a scale of 20-30 nm. In comparison, we have previously found that PMTMA is miscible with poly(p-vinylphenol) and the two polymers mix intimately on a scale of 1-3 nm.     

Fibre management technique for optical device integration oncircuit board with hundreds of optical connections

The authors present a technique for fibre management on a circuit board, which utilises newly-developed, flexible optical fibre circuits and multifibre physical contact connectors. The technique achieves compact fibre wiring and easy fibre connection for hundreds of fibres on a circuit board. The authors have fabricated a compact 8×16 delivery and coupling switch board using the technique     

Parallel Approximation Schemes for problems on planar graphs

 This paper describes a technique to obtain NC Approximations Schemes for the Maximum Independent Set in planar graphs and related optimization problems. The strategy consists in decomposing the graph into k-outerplanar subgraphs and solve for each k-outerplanar using tree contraction techniques. Received November 2, 1993/February 14, 1995     

Prevalence of and risk factors for Helicobacter pylori infection in a multi-racial dyspeptic Malaysian population undergoing endoscopy

The aim of the present study was to determine the risk factors for Helicobacter pylori in a dyspeptic Malaysian population. A cross-sectional survey of 1060 consecutive patients presenting with dyspepsia at the Endoscopic Unit, University Hospital, Kuala Lumpur, Malaysia from January 1994 to July 1995 was undertaken. All patients answered a detailed questionnaire and underwent endoscopy, with two antral biopsies taken for diagnosis of H. pylori using a rapid urease test. An overall H. pylori prevalence of 49.0% was recorded. Helicobacter pylori prevalence in relation to the major endoscopic diagnoses were as follows: non-ulcer dyspepsia (NUD) 31.2%; duodenal ulcer (DU) 91.4%; and gastric ulcer (GU) 74.1%. The prevalence among the races were as follows: Malay 16.4%; Chinese 48.5%; and Indians 61.8%. Multiple logistic regression analysis identified the following as independent risk factors: > 45 years old 1.5 (1.1,2.0); male gender 1.6 (1.2,2.1); ethnic group: Chinese 2.5 (1.7,3.7); Indians 4.9 (3.2,7.5); level of education: low 2.3 (1.5,3.5); middle 1.7 (1.1,2.6); and smoking 1.6 (1.2,2.3). Analysis was also performed on DU, GU and non-UD patients separately; in both DU and GU patients, H. pylori prevalence was high regardless of age, sex, race or level of education. However, in DU patients, Indian race had an independent risk factor (Odds ratio = 7.8 (1.2,48.4)). The findings in the NUD group reflected the findings in the ?all patients' group; > 45 years old, male gender, Indian and Chinese race, and low level of education were also significant, independent risk factors. The overall differences in H. pylori prevalence between the different subgroups were mainly due to differences in the NUD group. The increased risk of H. pylori infection in Chinese and Indians points to either an inherent ethnic genetic predisposition or to socio-cultural practices peculiar to the particular race which may be responsible for transmission of the infection.     

A Study on Distribution Preservation Mechanism in Evolutionary Multi-Objective Optimization

This paper reviews a number of popular distribution preservation mechanisms and examines their characteristics and effectiveness in evolutionary multi-objective (MO) optimization. A conceptual framework consisting of solution assessment and elitism is presented to better understand the search guidance in evolutionary MO optimization. Simulation studies among different distribution preservation techniques are performed over fifteen representative distribution samples and the performances are compared based upon two distribution metrics proposed in this paper. The results and findings reported in this paper are valuable for better understanding of the working principle and characteristics of distribution preservation mechanisms, which are very useful for incorporating different distribution preservation features into MO evolutionary algorithms in a modular fashion or improving the effectiveness of existing preservation approaches.     

Human breast milk immunoglobulins G hydrolyze nucleotides

Catalytically active antibodies, abzymes, appear in the blood of mammals immunized with the analogs of transition state or in the case of autoimmune diseases. Until recently, it was not shown whether abzymes exist in the blood of apparently healthy subjects. We have discovered that secretory IgA (sIgA) from the milk of healthy mothers catalyze phosphorylation of a variety of proteins and that IgG can hydrolyze DNA and RNA. In this study for the first time it is shown that IgG from human milk (and their Fab-fragments) also catalyze hydrolysis of nucleoside mono-, di-, and triphosphates. The data meet certain stringent criteria, unambiguously indicating that the observed catalytic activity is associated with IgG rather than contaminating enzymes. Although the nucleotide-binding site of IgG is located in the light antibody chain, L-chains per se cannot hydrolyze NTP unlike the DNA-hydrolyzing abzymes. Kinetic and thermodynamic parameters that characterize the interaction of NTP and dNTP with IgG-abzymes were analyzed. Possible reasons for appearance of polyclonal abzymes with different catalytic activities in the milk of healthy mothers are considered.     

Component-based records: A novel method to record transaction design work

The growing pressures from global competitive markets signal the inevitable challenge for companies to rapidly design and develop new successful products. To continually improve design quality and efficiency, companies must consider how to speed design processes, minimise human-errors, avoid unnecessary iterations, and sustain knowledge embedded in the design process. All of these issues strongly concern one topic: how to make and exploit records of design activities. Using process modelling ideas, this paper introduces a new method called component-based records, in place of traditional design reports. The proposed method records transaction elements of the actual design processes undertaken in a design episode, which aims to continually improve design quality and efficiency, reduce designers’ workload for routine tasks, and sustain competitiveness of companies.