Output control design and separation principle for a class of port‐Hamiltonian systems

Using a structure preserving observer, a dynamic output controller is proposed for a class of port‐Hamiltonian systems. The core of this method is based on the notion of contractive port‐Hamiltonian systems. The proposed method utilizes an extended form of IDA‐PBC (interconnection and damping assignment passivity‐based control), a well‐known controller design method for port‐Hamiltonian systems and paves the way for using IDA‐PBC in output control design of challenging control objectives, such as output tracking for underactuated mechanical systems. In the line of output control design, a useful separation principle for a class of port‐Hamiltonian systems is achieved, which is valuable in the field of nonlinear systems. Some simulations on magnetic levitation and ball on wheel testbeds show the potency and applicability of the proposed method.     

Microstructure and mechanical properties of dual phase steels,with different martensite morphology,produced during TLP bonding of a low C-Mn steel

In this research, production of ferrite - martensite dual phase Steels with different martensite morphology was considered during transient liquid phase bonding of a low carbon steel. The steel was bonded using an iron base interlayer with melting point of 1443 K and 40 μm thickness. Bonding process carried out at 1473 K, under pressure of 0.5 MPa, at different holding time of 10, 20, 30 and 40 minutes. Microstructural studies of joint region showed that isothermal solidification completed at the bonding time of 40 minutes. Microstructure of joints made at the bonding time of 10, 20, and 30 minutes consists of two distinct region, athermal and isothermal solidified zones. Microstructure of these zones was studied and chemical composition of these zones was determined by EDS. Joints made with bonding time of 40 minutes were homogenized at 1008 K and then cooled into cold water to produce dual phase ferrite and martensite microstructure with different martensite morphology. According to shear test results, it was found that the shear strength of ferrite - fibrous martensite microstructure is greater than those with ferrite - continuous martensite and ferrite - blocky martensite microstructure.     

Practical Output Regulation of Uncertain Strict‐Feedback Form Systems

In this paper, an output feedback control is proposed to solve the practical output regulation problem of a class of nonlinear systems. In the first step of the design procedure, two sets of coordinate transformations are used to convert the output regulation problem of the system in the strict‐feedback form into the regulation problem of the transformed system in the uncertain normal form. Then, for the resulting system, a state feedback in the cast of nested sliding mode control is designed. Finally, by using the nonlinear separation principle, the output feedback controller is achieved by substituting the estimated states, resulting from the high‐gain observer, instead of real states. It can be shown that the states of the closed‐loop system are ultimately bounded. Copyright © 2011 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

Deposition of palladium submonolayer on nanoporous gold film and investigation of its performance for the methanol electrooxidation reaction

The electrocatalytic activity of nanoporous gold film (NPGF) toward methanol oxidation reaction (MOR) upon Pd deposition is studied. Pd_θNPGFs (where, θ stands for the surface coverage of Pd on NPGF: 0.07, 0.19, 0.37 and 0.59) are prepared via surface engineering of NPGF using underpotential deposition (UPD) and galvanic replacement method.     

A new outer‐rotor flux switching permanent magnet generator for wind farm applications

In this paper a 1.5 kW flux switching permanent magnet (FSPM) generator is presented for direct drive small scale wind turbine applications. For maximizing induced voltage and the output torque while minimizing cogging torque and unbalanced radial magnetic force (UMF), the proposed machine exhibits a new 6/19 stator pole/rotor teeth number and an outer rotor configuration. At first, in the paper an analytical design has been developed, then a finite element method (FEM) analysis is carried out for validating the analytical procedure and for design improvement. The simulation results extracted by FEM confirm the theoretical analysis procedure and help in the understanding of the performance analysis of the machine against the variations of the design variables. Furthermore, an experimental laboratory prototype of the proposed FSPM is implemented to confirm the analytical design and FEM modelling approaches. A comparison of induced voltage, torque, UMF and cogging torque produced by different FSPM configurations present in literature respect to the proposed generator has been developed. The results show the goodness of the adopted methodology and prove that, because of suitable electromagnetic performance of the proposed FSPM generator, it could be counted as a proper candidate for small scale wind turbine applications. Copyright © 2016 John Wiley & Sons, Ltd.     

A neuro‑observer‑based optimal control for nonaffine nonlinear systems with control input saturations

In this study, an adaptive neuro-observer-based optimal control (ANOPC) policy is introduced for unknown nonaffinenonlinear systems with control input constraints. Hamilton–Jacobi–Bellman (HJB) framework is employed to minimize anon-quadratic cost function corresponding to the constrained control input. ANOPC consists of both analytical and algebraicparts. In the analytical part, first, an observer-based neural network (NN) approximates uncertain system dynamics,and then another NN structure solves the HJB equation. In the algebraic part, the optimal control input that does not exceedthe saturation bounds is generated. The weights of two NNs associated with observer and controller are simultaneouslyupdated in an online manner. The ultimately uniformly boundedness (UUB) of all signals of the whole closed-loop systemis ensured through Lyapunov’s direct method. Finally, two numerical examples are provided to confirm the effectiveness ofthe proposed control strategy.     

A novel approach to fairness-aware energy efficiency in green heterogeneous cellular networks

Wireless Networks - Heterogeneous cellular networks are a viable solution in response to the growing demand for broadband services in the new-generation wireless networks. The dense deployment of...     

Vacuum enhanced membrane distillation for trace contaminant removal of heavy metals from water by electrospun PVDF/TiO<Subscript>2</Subscript> hybrid membranes

Electrospun hybrid membranes were synthesized using electrospinning of Poly (vinylidenefluoride) - titanium tetraisopropoxide (PVDF-TTIP) sol. Asymmetric post-treatment of membrane conducted for deprotonation of titanate and making hydrophilic/hydrophobic dual characteristics. The membranes were characterized by various methods such as wettability, scanning electron microscopy, infrared spectroscopy, X-ray diffraction and liquid entry pressure tests. For evaluating the separation performance, these membranes were applied in the VMD process to treat water heavy metal contaminants. The effects of operating parameters such as flow rate, temperature and membrane properties as porosity, on contaminant removal and producing ultra-pure water have been studied.     

Effect of β-cyclodextrin on dissolution of methane in water

In this research the effects of β-cyclodextrin (CD) on dissolution of methane in water have been investigated. The tests were performed at pressures 3 and 5 bars and temperatures 1, 3, 5, 10, 15, 20, 25 and 30 °C. Three solutions constituted from different concentrations of CD were used. Each solution volume was 300 CC.Methane was contacted with each solution in a cell and data of gas pressure vs. time and the total absorption capacity were collected. Addition of 0.5 wt% cyclodextrin increased the capacity of methane absorption as much as 14.63% at temperature 1 °C and primary pressure 3 bars, while the effect of its addition was reduced with temperature increase. Utilization of CD improved the pressure reduction slope of methane at low temperatures. Finally the graphs P-T-t at two initial pressures 3 and 5 bars were plotted for each solution.