Search

A practical fixed-time fault estimation observer strategy for non-linear systems using an unknown input observer scheme is investigated. The external disturbances of non-linear systems are decoupled by an unknown input observer technique; therefore, the constructed error dynamics do not include these disturbances. The fixed-time fault estimation observer is then constructed. Moreover, a non-linear fault estimator with two power functions is proposed to improve the convergence speed of fault estimation. Finally, simulation results of a non-linear Lorenz chaotic system are provided to demonstrate the feasibility of the presented strategy. [ABSTRACT FROM AUTHOR]

In this article, the issue of distributed sensor fault estimation with resilient property is studied for a class of multi‐agent systems. Based on the relative output information, a novel fault estimation design is presented to estimate sensor fault and state vectors simultaneously. Meanwhile, the variation of observer gain is considered to improve the robustness of fault estimation observer. Furthermore, robust l2−l∞ performance is used to suppress the influence of external interference on sensor fault estimation error. Finally, simulations are provided to present effectiveness of the developed approach. [ABSTRACT FROM AUTHOR]

The design of a robust fault estimation observer is studied for linear multiagent systems subject to incipient faults. By considering the fact that incipient faults are in low-frequency domain, the fault estimation of such faults is proposed for discrete-time multiagent systems based on finite-frequency technique. Moreover, using the decomposition design, an equivalent conclusion is given. Simulation results of a numerical example are presented to demonstrate the effectiveness of the proposed techniques. [ABSTRACT FROM AUTHOR]

Abstract: We have developed a simple and label-free electrochemical assay to detect CGG trinucleotide repeat. For this purpose, a new bifunctional probe (FecNCD2) was developed, in which a recognition part (naphthyridine carbamate dimmer, NCD) was connected with an electro-active part (ferrocenyl group) using a chain of –CO–NH–CH2–CH2–. The results of circular dichroismic measurements indicated that FecNCD2 exhibited a superior performance for selective binding to CGG trinucleotide repeats compared to a previous bifunctional electrochemical probe connected with shorter linker –CH2– (FecNCD1). Then, the electrochemical properties of FecNCD2 were evaluated and were found to show a good redox response due to the ferrocene moiety. Owing to the high performances of FecNCD2, the label-free electrochemical biosensor for CGG repeats was constructed by immobilizing them onto gold disk electrode and by using FecNCD2 as an electrochemical probe in solution. Further CGG repeats in solution were confirmed to be detectable using the CGG modified biosensor in competitive experiments, i.e., by treating it in test solutions containing FecNCD2 and d(CGG)10 or others. No interference of ct-DNA on the CGG detection was also confirmed with this approach. The strategy should have significant potential for the development of versatile and low-cost biosensor for early diagnosis and treatment of neurodegenerative diseases associated with trinucleotide repeats. [Copyright &y& Elsevier]

Abstract: A new electrochemical assaying approach with label-free to identify GG mismatch in DNA duplexes was developed by applying a new double functional probe (FecNC), ferrocenyl modified naphthyridine derivative, which contain recognition domain (naphthyridine derivative) and electroactive center (ferrocenyl group). The double functional probe exhibited not only the excellent electrochemical response devoted from ferrocenyl but also high selective electrochemical signal “off” for G–G mismatch duplex. The interaction was also verified by melting temperature and circular dichroismic spectra (CD). The electrochemical investigation showed that the redox of FecNC was a diffusion-controlled process and the diffusion coefficient of bound-FecNC was much smaller than free FecNC. The correlation between the current of FecNC and concentration of GG mismatch duplex indicated that the bind saturation point was about at a 1:1 mole ratio. The novel double functional electrochemical probe might provide a versatile and low-cost way to detect single nucleotide polymorphisms, which could be found extensive applications in the diagnosis of the genetic diseases. [Copyright &y& Elsevier]

Abstract: New ferrocene naphthyridine derivatives were successfully synthesized. The di-substituted ferrocene derivative FecDN behaves as a selective visual chemosensor for mercury ions, exhibiting a rapid and clearly visible precipitation with good selectivity (precipitation) and sensitivity (0.01μM). The interaction of the ferrocene derivatives and metal ions was investigated by ultraviolet–visible spectroscopy (UV–vis), electrochemical methods, 1H NMR, as well as infrared (IR), and energy dispersive X-ray spectroscopy (EDX). The application of FecDN in the detection and removal of mercury ions is very simple, rapid, and intuitive. [Copyright &y& Elsevier]