Robust H(infinity) tracking control of boiler-turbine systems

In this paper, the problem of designing a fuzzy H(infinity) state feedback tracking control of a boiler-turbine is solved. First, the Takagi and Sugeno fuzzy model is used to model a boiler-turbine system. Next, based on the Takagi and Sugeno fuzzy model, sufficient conditions for the existence of a fuzzy H(infinity) nonlinear state feedback tracking control are derived in terms of linear matrix inequalities. The advantage of the proposed tracking control design is that it does not involve feedback linearization technique and complicated adaptive scheme. An industrial boiler-turbine system is used to illustrate the effectiveness of the proposed design as compared with a linearized approach.

Ethanol production of semi-simultaneous saccharification and fermentation from mixture of cotton gin waste and recycled paper sludge

Ethanol production from the steam-exploded mixture of 75% cotton gin waste and 25% recycled paper sludge in various conditions was investigated by semi-simultaneous saccharification and fermentation (SSSF) consisting of a pre-hydrolysis and a simultaneous saccharification and fermentation (SSF). Four cases were studied: 24-h pre-hydrolysis + 48-h SSF (SSSF 24), 12-h pre-hydrolysis + 60-h SSF (SSSF 12), 72-h SSF, and 48-h hydrolysis + 24-h fermentation (SHF). The ethanol concentration, yield, and productivity of SSSF 24 were higher than those of the other operations. A model of SSF was used to simulate the data for four components in SSF. The analysis of the reaction rates of cellobiose, glucose, cell, and ethanol using the model and the parameters from the experiments showed that there was a transition point of the rate-controlling step at which the cell growth control in the initial 2 h was changed to the cellobiose reaction control in later period during ethanol production of SSF from the mixture.

Note: Determination of effective gas diffusion coefficients of stainless steel films with differently shaped holes using a Loschmidt diffusion cell

In this work, an in-house made Loschmidt diffusion cell is used to measure the effective O(2)-N(2) diffusion coefficients through four porous samples of different simple pore structures. One-dimensional through-plane mass diffusion theory is applied to process the experimental data. It is found that both bulk diffusion coefficient and the effective gas diffusion coefficients of the samples can then be precisely determined, and the measured bulk one is in good agreement with the literature value. Numerical computation of three-dimensional mass diffusion through the samples is performed to calculate the effective gas diffusion coefficients. The comparison between the measured and calculated coefficient values shows that if the gas diffusion through a sample is dominated by one-dimensional diffusion, which is determined by the pore structure of the sample, these two values are consistent, and the sample can be used as a standard sample to test a gas diffusion measurement system.

Features of leprosy transmission in pocket villages at low endemic situation in China

To study the characteristics of leprosy transmission at low endemic situation and to analyze the reason why transmission still existed. A retrospective study was carried out on transmission of leprosy in thirteen leprosy high endemic villages in Wenshan district, Yunnan Province, China. A special questionnaire was designed for collecting the data. A total of 47 patients have been registered in 13 villages since 1991. Among them, 25 (53.2%) were leprosy household patients. The proportion of BI positivity was 57.4% (27). The average delay time from disease onset to diagnosis of leprosy was 12 +/- 7.9 months with a range of 1-36 months. The interval between 2 cases being detected in each village was in a range of 0.5 to 5.5 years. Many secondary patients occurred continuously after an 'index case' and they developed leprosy within the delay time of the disease of former patients. The authors here also reviewed some literature on chemoprophylaxis and discussed the importance. Most patients could not be detected at the early stage. It may be necessary of considering the chemoprophylaxis strategy among close contacts of leprosy to stop transmission in leprosy pocket areas.

Self-Organized Ni Nanocrystal Embedded in BaTiO3 Epitaxial Film

Ni nanocrystals (NCs) were embedded in BaTiO3 epitaxial films using the laser molecular beam epitaxy. The processes involving the self-organization of Ni NCs and the epitaxial growth of BaTiO3 were discussed. With the in situ monitoring of reflection high-energy electron diffraction, the nanocomposite films were engineered controllably by the fine alternation of the self-organization of Ni NCs and the epitaxial growth of BaTiO3. The transmission electron microscopy and the X-ray diffraction characterization confirmed that the composite film consists of the Ni NCs layers alternating with the (001)/(100)-oriented epitaxial BaTiO3 separation layers.

Dynamics of microRNA-mediated motifs

In the past, most research on gene regulation has focused on transcriptional regulation and post-translational regulation. Recently, the post-transcriptional regulation by small non-coding RNAs has drawn much attention. This mode of regulation was found in both prokaryotes and eukaryotes. In this study, the authors integrate transcriptional and post-transcriptional regulation into four different kinds of microRNA-mediated motifs and investigate the mechanism of microRNAs regulation from the viewpoints of dynamics. Theoretical analysis and numerical simulations show that all the four motifs exhibit strong robustness to external and stochastic perturbations.

A composite scoring of genotypes discriminates coronary heart disease risk beyond conventional risk factors in the Boston Puerto Rican Health Study

BACKGROUND AND AIMS

Using a genetic predisposition score (GPS), integrating the additive associations of a set of single nucleotide polymorphisms (SNPs) with CHD, we examined the consequences of the joint presence of a high GPS and conventional risk factors (CRFs).

METHODS AND RESULTS

We studied 11 SNPs at eight loci in 197 participants with prior CHD and 524 CHD-free subjects from the Boston Puerto Rican Health Study. Each polymorphism contributed 1 unit (high-risk allele homozygous), 0.5 units (heterozygous) and 0 units (low-risk allele homozygous) to the GPS. Odds ratio (OR) of CHD for those at high risk because of GPS (>5) and simultaneous presence of CRFs were estimated, compared with subjects at low risk, for both measurements. The mean score was higher in participants with prior CHD than those CHD-free (P=0.015), and the OR for CHD with a GPS>5 was 2.90 (P<0.001).The joint presence of a high GPS and each CRF was associated with higher risk of CHD. Compared to participants with high GPS, those with low GPS (<or=5) were protected against CHD even if they were smokers (OR=0.44), heavy drinkers (OR=0.43), displayed low physical activity (OR=0.35), had hypertension (OR=0.52) or hyperlipidemia (OR=0.34) (P values ranging from 0.004 to 0.023).

CONCLUSION

A simple genetic score of 11 polymorphisms may identify those subjects at increased risk of CHD beyond conventional risk factors.

Meta-analysis: the effect and adverse events of Lactobacilli versus placebo in maintenance therapy for Crohn disease

BACKGROUND

Lactobacilli are used in an attempt to maintain remission for Crohn disease. The aim of this study was to evaluate the efficacy and adverse events of Lactobacilli compared with placebo in maintenance therapy for Crohn disease.

METHODS

We searched MEDLINE, EMBASE, the Cochrane Controlled Trials Register, OVID and BIOSIS. All randomized trials comparing Lactobacilli with placebo in maintenance therapy for Crohn disease were included.

RESULTS

Six randomized controlled trials with a total of 359 participants met the inclusion criteria. From the meta-analyses, the relative risk (RR) of clinical relapse rate was 1.15 (95% confidence interval (CI) 0.90-1.48) comparing Lactobacilli with placebo and RR of endoscopic relapse rate was 1.31 (95%CI 0.57-3.00). Subgroup analyses showed RR for clinical relapse rates of Lactobacilli versus placebo was 0.99 (95%CI 0.76-1.29) in adults, 1.85 (95%CI 1.00-3.41) in children, 1.68 (95%CI 1.07-2.64) in Lactobacillus rhamnosus strain GG and 0.91 (95%CI 0.68-1.23) in Lactobacillus johnsonii respectively. The pooled RR of adverse events was 0.83 (95%CI 0.61-1.12).

CONCLUSION

Our meta-analysis suggests that compared with placebo, administration of L. rhamnosus strain GG as maintenance therapy may increase the relapse rates of Crohn disease. L. johnsonii is inefficacious in reducing the incidence of relapse.