Iterative performance improvement of fuzzy control systems for three tank systems

This paper suggests the performance improvement of fuzzy control systems (FCSs) for three tank systems using iterative feedback tuning (IFT). The stable design of Takagi–Sugeno–Kang fuzzy controllers is guaranteed by means of a stability theorem based on LaSalle’s global invariant set theorem formulated for a class of multi input-multi output (MIMO) nonlinear processes. An IFT algorithm characterized by setting the step size to guarantee the FCS stability is proposed. The theoretical approaches are applied in a case study that deals with the IFT-based stable design of fuzzy controllers dedicated to the level control of a cylindrical three tank system as a representative MIMO system. A set of experimental results for a laboratory setup illustrates the performance improvement.     

The ETH‐MAV Team in the MBZ International Robotics Challenge

This study describes the hardware and software systems of the Micro Aerial Vehicle (MAV) platforms used by the ETH Zurich team in the 2017 Mohamed Bin Zayed International Robotics Challenge (MBZIRC). The aim was to develop robust outdoor platforms with the autonomous capabilities required for the competition, by applying and integrating knowledge from various fields, including computer vision, sensor fusion, optimal control, and probabilistic robotics. This paper presents the major components and structures of the system architectures and reports on experimental findings for the MAV‐based challenges in the competition. Main highlights include securing the second place both in the individual search, pick, and place the task of Challenge 3 and the Grand Challenge, with autonomous landing executed in less than 1 min and a visual servoing success rate of over for object pickups.     

Using thorium to reduce the maximum fuel temperatures during depressurized loss of coolant accidents in a once-through-then-out (OTTO) PBMR DPP-400 core

This article presents the results for the PBMR-DPP-400, but for a once-through-then-out (OTTO) refueling scheme. An optimization attempt of the axial and radial power profiles is reported. The main aim was to reduce the maximum depressurized loss of forced coolant (DLOFC) temperature by adding thorium to the fuel and making the fuel layout radially asymmetric by placing lower enriched fuel in the inner and higher enriched fuel in the outer fuel flow regions. These measures (1) flattened the peaks in the axial power profiles and thus suppressed the hotspots in the axial DLOFC temperature profiles and (2) ‘pushed’ the power radially outwards, so as to reduce the distance that the decay heat must be evacuated towards the outside of the fuel core. This resulted in a huge reduction in the maximum DLOFC temperature for the OTTO cycle from 2273 to 1811 °C, which is still above the 1600 °C limit but represents a remarkable result. Maximum DLOFC temperature below the 1600 °C limit was obtained by reducing the power output. The results obtained and the proposed strategies for further improvement are applicable to the Chinese HTR-PM and could produce even better results in Prismatic Block Reactors such as the Japanese HTTR.     

Spectroscopic Studies of Model Photo-Receptors: Validation of a Nanosecond Time-Resolved Micro-Spectrophotometer Design Using Photoactive Yellow Protein and α-Phycoerythrocyanin

Time-resolved spectroscopic experiments have been performed with protein in solution and in crystalline form using a newly designed microspectrophotometer. The time-resolution of these experiments can be as good as two nanoseconds (ns), which is the minimal response time of the image intensifier used. With the current setup, the effective time-resolution is about seven ns, determined mainly by the pulse duration of the nanosecond laser. The amount of protein required is small, on the order of 100 nanograms. Bleaching, which is an undesirable effect common to photoreceptor proteins, is minimized by using a millisecond shutter to avoid extensive exposure to the probing light. We investigate two model photoreceptors, photoactive yellow protein (PYP), and α-phycoerythrocyanin (α-PEC), on different time scales and at different temperatures. Relaxation times obtained from kinetic time-series of difference absorption spectra collected from PYP are consistent with previous results. The comparison with these results validates the capability of this spectrophotometer to deliver high quality time-resolved absorption spectra.     

Chemomechanical Systems: Study of Contraction and Mechanical Work of Poly(Acrylonitrile) Gel Fibers

Poly(acrylonim1e) fibers were preoxidated under stress, in the presence of air, then saponified by boiling in alkaline solutions. The chemomechani-cal behavior of these fibers, expressed as contraction and mechanical work, under different loads and in different solvent-nonsolvent and/or base-acid systems were investigated. Total nitrogen content, carboxyl groups content, tensile strength, and cross-link density were determined. Both contraction and mechanical work were expressed as functions of applied load in every studied system. The results of chemomechanical measurements were connected to those of chemical and physical investigations. Significant differences in chemomechanical behavior were found to be the result of different stress conditions during the preoxidation stage.     

Cancer Stem Cells: Biological Functions and Therapeutically Targeting

Almost all tumors are composed of a heterogeneous cell population, making them difficult to treat. A small cancer stem cell population with a low proliferation rate and a high tumorigenic potential is thought to be responsible for cancer development, metastasis and resistance to therapy. Stem cells were reported to be involved in both normal development and carcinogenesis, some molecular mechanisms being common in both processes. No less controversial, stem cells are considered to be important in treatment of malignant diseases both as targets and drug carriers. The efforts to understand the role of different signalling in cancer stem cells requires in depth knowledge about the mechanisms that control their self-renewal, differentiation and malignant potential. The aim of this paper is to discuss insights into cancer stem cells historical background and to provide a brief review of the new therapeutic strategies for targeting cancer stem cells.     

Evidence of Tin Oxide Recrystallization in Opacified Lead Glazes

Tin oxide (SnO₂) particles that are a few hundred nanometers in size and are embedded in a lead glaze act as a white opacifier. The insolubility of SnO₂ particles in a lead glaze is responsible for this microstructure. Although it is assumed that SnO₂ particles do not react during the glaze formation, we demonstrate that the development of metastable phases prior to the fusion of the PbO-SiO₂-SnO₂ mixture allows the SnO₂ particles to react and then recrystallize subsequent to the fusion of the mixture. The recrystallization of SnO₂ occurs during heating and/or cooling until the temperature is sufficiently low and/or the tin supply is exhausted.