Adaptive fuzzy control of DC motors using state and output feedback

Conventional PID of state feedback controllers for DC motors have poor performance when changes of the motor or load dynamics take place. To handle this shortcoming adaptive fuzzy control of DC motors is proposed. Neuro-fuzzy networks are used to approximate the unknown motor dynamics. The information needed to generate the control signal comes from feedback of the full state vector or from feedback of only the system’s output. In the latter case a state observer is used to estimate the parameters of the state vector. The stability of the closed-loop system is proved with the use of Lyapunov analysis. The performance of the proposed control approach is evaluated through simulation tests.     

Particle and Kalman filtering for state estimation and control of DC motors

State estimation is a major problem in industrial systems. To this end, Gaussian and nonparametric filters have been developed. In this paper the Kalman Filter, which assumes Gaussian measurement noise, is compared to the Particle Filter, which does not make any assumption on the measurement noise distribution. As a case study the estimation of the state vector of a DC motor is used. The reconstructed state vector is used in a feedback control loop to generate the control input of the DC motor. In simulation tests it was observed that for a large number of particles the Particle Filter could succeed in accurately estimating the motor’s state vector, but at the same time it required higher computational effort.     

The Role of Exosomal Non-Coding RNAs in Colorectal Cancer Drug Resistance

Background: Colorectal cancer (CRC) is one of the most common types of cancer diagnosed worldwide with high morbidity; drug resistance is often responsible for treatment failure in CRC. Non-coding RNAs (ncRNAs) play distinct regulatory roles in tumorigenesis, cancer progression and chemoresistance. Methods: A literature search was conducted in PubMed database in order to sum up and discuss the role of exosomal ncRNAs (ex-ncRNAs) in CRC drug resistance/response and their possible mechanisms. Results: Thirty-six (36) original research articles were identified; these included exosome or extracellular vesicle (EV)-containing microRNAs (miRNAs), long non-coding RNAs (lncRNAs), circular RNAs (circRNAs) and small-interfering (siRNAs). No studies were found for piwi-interacting RNAs. Conclusions: Exosomal transfer of ncRNAs has been documented as a new mechanism of CRC drug resistance. Despite being in its infancy, it has emerged as a promising field for research in order to (i) discover novel biomarkers for therapy monitoring and/or (ii) reverse drug desensitization.     

Hybrid graphene-quantum dot phototransistors with ultrahigh gain

Graphene is an attractive material for optoelectronics and photodetection applications because it offers a broad spectral bandwidth and fast response times. However, weak light absorption and the absence of a gain mechanism that can generate multiple charge carriers from one incident photon have limited the responsivity of graphene-based photodetectors to ～10(-2)?A?W(-1). Here, we demonstrate a gain of ～10(8) electrons per photon and a responsivity of ～10(7)?A?W(-1) in a hybrid photodetector that consists of monolayer or bilayer graphene covered with a thin film of colloidal quantum dots. Strong and tunable light absorption in the quantum-dot layer creates electric charges that are transferred to the graphene, where they recirculate many times due to the high charge mobility of graphene and long trapped-charge lifetimes in the quantum-dot layer. The device, with a specific detectivity of 7?×?10(13) Jones, benefits from gate-tunable sensitivity and speed, spectral selectivity from the short-wavelength infrared to the visible, and compatibility with current circuit technologies.     

Efficient Infrared Electroluminescent Devices Using Solution‐Processed Colloidal Quantum Dots

We report efficient electroluminescence in the near‐infrared from PbS–MEH‐PPV (poly(2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylenevinylene)) large‐area, solution‐cast nanocomposite devices. We employ multivariate optimization of the structural and materials components that govern the radiative, energy‐transfer, and bipolar‐injection efficiencies into the devices. As a result, we report an external electroluminescence quantum efficiency of 0.27 %, which corresponds to an internal electroluminescence quantum efficiency of 1.9 %. The very best devices exhibit internal‐radiative‐efficiency‐limited performance and not transport‐ or capture‐limited performance, indicating that further gains in efficiency may be achieved if the internal radiative efficiency of the nanocrystal–polymer composite can be further increased without compromising transfer and device bipolar‐injection efficiency.     

A Monte Carlo pore network for the simulation of porous characteristics of functionalized silica: pore size distribution, connectivity distribution and mean tortuosities

The simulation of the random porous network of five samples of functionalized SiO₂ took place using a dual-site-bond model (DSBM) and Monte Carlo techniques for achieving the proper arrangement of the pores into the system. The simulation took place in 7×7×7 lattice. As a starting point of simulation the adsorption branch of N₂ isotherm was considered from which the pore size distribution was estimated. Then as a benchmark of simulation the N₂ desorption branch was considered whose fitting was achieved using the Monte Carlo technique for selecting the proper place of each pore into the 7×7×7 lattice. From the obtained model, it was possible to estimate the distribution of pore connectivities of each system. The mean value of those connectivity distributions tallies with the corresponding mean values estimated using the standard methodology of Seaton. In addition, the mean tortuosity of the porous network was estimated and the results were favorably compared with values of tortuosity estimated recently via the so-called corrugated-pore-structure-model (CPSM) for the same solids. The degree of functionalization of the parent SiO₂ affects both connectivity and tortuosity in a linear way. Some discrepancies observed between the results obtained via this methodology and the ones obtained using the Seaton or the CPSM model are discussed.     

Period doubling and complex dynamics in an isothermal chemical reaction system

Stability and bifurcation theory have been used to organize a computational study of the dynamics of a three-variable isothermal reaction system with quadratic kinetics. This system exhibits a cascade of period-doubling bifurcations over decreasing intervals of parameter changes. This simple example illustrates a wide variety of complicated dynamics and shows that the qualitative dynamic features of isothermal reaction systems may be extremely sensitive to parameter values.     

Solution-processed PbS quantum dot infrared photodetectors and photovoltaics

In contrast to traditional semiconductors, conjugated polymers provide ease of processing, low cost, physical flexibility and large area coverage. These active optoelectronic materials produce and harvest light efficiently in the visible spectrum. The same functions are required in the infrared for telecommunications (1,300-1,600 nm), thermal imaging (1,500 nm and beyond), biological imaging (transparent tissue windows at 800 nm and 1,100 nm), thermal photovoltaics (>1,900 nm), and solar cells (800-2,000 nm). Photoconductive polymer devices have yet to demonstrate sensitivity beyond approximately 800 nm (refs 2,3). Sensitizing conjugated polymers with infrared-active nanocrystal quantum dots provides a spectrally tunable means of accessing the infrared while maintaining the advantageous properties of polymers. Here we use such a nanocomposite approach in which PbS nanocrystals tuned by the quantum size effect sensitize the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy-p-phenylenevinylene)] (MEH-PPV) into the infrared. We achieve, in a solution-processed device and with sensitivity far beyond 800 nm, harvesting of infrared-photogenerated carriers and the demonstration of an infrared photovoltaic effect. We also make use of the wavelength tunability afforded by the nanocrystals to show photocurrent spectra tailored to three different regions of the infrared spectrum.