Combined passivity based control and optimal control for energy management of fuel cell/battery hybrid system

The energy management of hybrid electric vehicles is becoming an interesting topic for many researchers. Furthermore, the wise choice of the energy management strategy allows not only the best distribution of the power between the used sources, but also it allows reduction of consumption, increase in the lifetime of the sources, and improves the autonomy of the hybrid electric vehicle. The autonomy is guaranteed by the optimization of the embedded sources. In this study, the hybrid system consists of combining the fuel cell as the main source with the battery as the auxiliary source. The novelty of the proposed energy management strategy for the studied hybrid system is the combination between interconnection and damping assignment‐passivity based control and the Hamiltonian Jacobi Bellman method. The stability proof is given and the efficiency of the proposed strategy is proved by the experimental work, where the obtained results show the good and adequate results to the proposed scenario.     

Hybrid control design for limit cycle stabilisation of planar switched systems

This paper addresses the control problem of an important class of hybrid dynamical systems where the desired state does not belong to the set of subsystem equilibria. Beyond the practical stabilisation where the system trajectory has to be driven to a neighbourhood of a desired state, a control law is designed to solve the limit cycle stabilisation problem for planar hybrid systems. Using the hybrid Poincaré map, two hybrid controllers are developed, which guarantee a local asymptotic/finite-time stability of the desired limit cycle. Illustrative examples are provided to highlight the effectiveness of the derived results.     

Efficiency of Radiolabeled Silver Nanoflowers as Theranostic Agent

Radiochemistry - Silver nanoflowers (Ag1 and Ag2 NFws) were prepared using combined solid state–polyol reduction methods. The nanoflowers were characterized by X-ray diffraction, scanning...     

Characterization and sustainable management strategies of municipal solid waste in Egypt

Clean Technologies and Environmental Policy - The aim of the present study was to establish a national database of waste characteristics for Egypt to support the assessment of various waste...     

Stabilising and Trimming 3D Woven Fabrics for Composite Preforming Applications

The work presented here focusses on the developments in the stabilising and trimming of 3D woven preforms. Dry fibre preforms are notoriously difficult to trim; once a fabric is cut, it loses its edge stability and consequently the fabric frays. The result is an unstable fabric which can easily be displaced/ distorted prior to composite manufacturing. In this work, three stabilisation and three trimming techniques were investigated. Of the stabilisation techniques these included powder binder, thermoplastic binder yarn (activated to give fabric stabilization); and polyester stitching. The stabilised fabrics were trimmed to near-net-shape using different trimming techniques. The trimming techniques investigated were laser, clicker press and ultrasonic knife. Each stabilisation method was trialled with each trimming method to assess the most suitable combination. The assessment of quality and suitability was made by observing the level of stabilisation, amount of fraying fibres, quality of the cut, ease of application and repeatability of the process. This paper details the assessments made for each combination alongside practical application conclusions. The key findings were; cutting by means of a laser is capable of sealing the fabric edges, producing high edge quality. Stitching as a method of stabilising is not sufficient in preventing fibres from moving during the cutting process, hence producing an unclean cut.     

Study of Magnetic Entropy Change in Nd<Subscript>0.67</Subscript>Ba<Subscript>0.33</Subscript>Mn<Subscript>0.98</Subscript>Fe<Subscript>0.02</Subscript>O<Subscript>3</Subscript> by Means of Theoretical Models

Magnetic entropy change (?ΔS _M ) of Nd_0.67 Ba_0.33Mn_0.98Fe_0.02O₃ perovskite have been analyzed by means of theoretical models. An excellent agreement has been found between the (ΔS_M) values estimated by Landau theory and those obtained using the classical Maxwell relation. In order to estimate the spontaneous magnetization M _{s pont}(T), we used the mean-field theory to analyses the (ΔS_M) vs. M ² data. The obtained M _{s pont}(T) values are in good agreement with those found from the classical extrapolation from the Arrott plots(H/M vs. M ²), confirming that the magnetic entropy is a valid approach to estimate the spontaneous magnetization in our system. At a relatively low magnetic field, a phenomenological model has been used to estimate the values of the magnetic entropy change. The results are in good agreement with those obtained from the experimental data using Maxwell relation.     

Numerical convergence of discrete exterior calculus on arbitrary surface meshes

Discrete exterior calculus (DEC) is a structure-preserving numerical framework for partial differential equations solution, particularly suitable for simplicial meshes. A longstanding and widespread assumption has been that DEC requires special (Delaunay) triangulations, which complicated the mesh generation process especially for curved surfaces. This paper presents numerical evidence demonstrating that this restriction is unnecessary. Convergence experiments are carried out for various physical problems using both Delaunay and non-Delaunay triangulations. Signed diagonal definition for the key DEC operator (Hodge star) is adopted. The errors converge as expected for all considered meshes and experiments. This relieves the DEC paradigm from unnecessary triangulation limitation.     

Experimental Investigation on the Effect of Tool Rotational Speed on Mechanical Properties of AA6082-T6 Friction Stir-Welded Butt Joints

Journal of Failure Analysis and Prevention - In this study, the effect of tool rotational speed on mechanical properties of AA 6082-T6 aluminum alloy was investigated. Different welded joints were...     

The Hysteresis Behavior of a Spin-1 Blume-Capel Nanoisland

The magnetic properties of a spin-1 Blume-Capel nanoisland are investigated by the use of the effective field theory based on the probability distribution technique. The influence of the random crystal field and the system parameters on the hysteresis behavior and on the magnetic properties of the nanoisland is examined. The results show a number of characteristic behaviors, such as the appearance of double, triple, quadruple, and even quintuple hysteresis loops for appropriate values of the system parameters.     

Dynamic risk assessment of complex systems using FCM

Analysing risk of today’s complex systems is challenging due to the complex and dynamic nature of systems. The current risk analysis tools are not able to take the complex interactions among risks into account and therefore they can’t predict the behaviour of risks accurately. In an attempt to overcome this shortcoming, this paper proposes an integrated generalised decision support tool using fuzzy cognitive maps for dynamic risk assessment of complex systems. The proposed approach has the ability to prioritise risk factors and more importantly predict and analysis the influences of each individual risk factor/risk set on the other risks or on the outcomes of complex and critical systems by taking into account probability of occurrence and consequences of risks and also considering the complex dependencies between risk factors. These features could provide practitioners with realistic results in critical industries and able them to manage risks more efficiently.