Upravljanje frekvencijom i radnom snagom mikro hidroelektrana kliznim režimom rada i redukcijom reda modela sustava

Micro hydro is treated as a major renewable energy resource. Such a kind of plants blooms because they can evade some dilemmas like population displacement and environmental problems. But their performance on the frequency index of power systems may be deteriorated in the presence of sudden small load perturbations and parameter uncertainties. To improve the performance, the problem of load frequency control (LFC) raises up. Design of state-based controllers on the aspect of modern control is challenging because only a part of the system states are measurable. This paper addresses the scheme of sliding mode control by model order reduction for the LFC problem of micro hydro power plants. The kind of plants usually has two operating modes, i.e., isolated mode and grid-connected mode. Under each operating mode, mathematical model and model reduction are investigated at first. According to the reduced-order model, a sliding mode control law is subsequently derived. Since the control law is applied to the original system, a sufficient condition about the system stability is proven in light of small gain theory. Simulation results illustrate the feasibility, validity and robustness of the presented scheme.Mikro hidroelektrane smatraju se jednim od glavnih obnovljivih izvora energije. Ovakve elektrane su poglavito zanimljive pošto izbjegavaju dileme vezane za iseljavanje ljudi i utjecaj na okoliš. Međutim, njihov učinak na indeks frekvencije energetskih sustava može biti negativan zbog naglih manjih promijena u opterećenju i nesigurnosti parametara. Kako bi se unaprijedila učinkovitost, javlja se problem regulacije frekvencije i radne snage. Projektiranje regulatora po varijablama stanja sustava izazovan je problem, jer je mjerljiv samo dio stanjasustava. Ovaj članak analizira problem upravljanja kliznim režimom rada reducirajući red modela sustava kod regulacije frekvencije i radne snage mikro hidroelektrana. Ovakve elektrane mogu raditi u samostalnom režimu rada ili biti spojene na distribucijsku mrežu. Za oba ražima rada prvo se istražuju matematički modeli te potom njihova redukcija. S obzirom na model reduciranog reda izvodi se upravljački zakon kliznog režima rada. Pošto se zakon upravljanja primjenjuje na izvorni sustav, dokazan je dovoljan uvjet za stabilnost u vidu teorije malog pojačanja.Simulacijski rezutati pokazuju izvedivost, ispravnost i robustnost predloženog pristupa

Cryptotanshinone Induces Apoptosis of HL-60 Cells via Mitochondrial Pathway

Purpose: To test the effect of Cryptotanshinone (CPT), a natural  compound isolated from the plant Salvia miltiorrhiza Bunge, on human leukemic cell lines (HL-60).Methods: HL-60 cells were treated with CPT. Cell growth inhibition (%) was quantitated using MTT assay. Apoptosis detection with Annexin  V-FITC/propidium iodide staining was followed by flow cytometry. Caspase-3, caspase-8, and caspase-9 colorimetric assay kit was used to determine caspase protease activity. Loss of mitochondrial membrane potential was examined by flow cytometry with JC-1 staining. Bax, PARP, p53, p21 and cytochrome C were determined using Western blot.Results: Morphologic assessment, Annexin V-FITC/propidium iodide  staining results and sub-G1 percentage indicate that the cytotoxic effect of CPT was mediated by induction of apoptosis. Furthermore, increased Bax expression, decreased Bcl-2 expression, loss of mitochondria membranepotential (MMP), release of cytochrome C, activation of caspase enzyme, cleavage of PARP and accumulation of p53 and p21 were detected during the apoptotic process. Caspase inhibitor partially abrogated CPT-induced apoptosis.Conclusion: The results show that CPT induced apoptosis of HL-60 cell lines by mitochondria pathway, and suggest that CPT may serve as a potential therapy for leukemia.Keywords: Cryptotanshinone, Salvia miltiorrhiza Bunge, Caspase,  Membrane potential, Mitochondrial, Apoptosis, Leukemia, Cytochrome C, Cell cycl

Bayesian analysis and applications of a model for survival data with a surviving fraction

Cure rate estimation is one of the most important issues in clinical trials and cure rate models are the main models. In the past decade, the standard cure rate model has been discussed and used. However, this model involves several drawbacks. Chen, Ibrahim and Sinha (1999) considered Bayesian methods for right-censored survival data for populations with a surviving (cure) fraction. In that paper, the authors proposed the cure rate model under the Weibull distribution which is quite different from the standard cure rate model. This proposed cure rate model overcomes the drawbacks of the standard cure rate model. However, it is not clear from their work whether their proposed cure rate models can be extended to other distributions. In this practicum, we shall extend those proposed cure rate models in Chen et al (1999) to the following distributions: log-logistic, Gompertz, and Gamma. Prior elicitations will also be discussed in detail, and classes of noninformative and informative prior distributions will be proposed. Furthermore, several theoretical properties of the proposed priors and resulting posteriors will be derived. -- At the end of this practicum, a melanoma clinical trial is used to illustrate applications of the log-logistic, Gompertz and Gamma distributions to the proposed cure rate models for Bayesian analysis. -- Keywords: Cure rate model; Historical data; Current data; Posterior distribution; Gamma distribution; Log-logistic distribution; Gompertz distribution