Model-based controller design for a lift-and-drop railway track switch actuator

Track switches are essential in order to enable railway vehicles to change routes however they are also the largest single cause of failure on the railway network. A new generation of switching concepts are emerging from projects like In2Rail, REPOINT and S-Code that promise to improve rail network performance through the use of new mechanisms, monitoring and control systems. This paper focusses on modelling and control of a lab-demonstrator from the REPOINT project. Unlike conventional track switch machines, this actuator needs closed loop feedback control. First, a detailed simulation model of the actuator is developed and validated against experimental results. Two model-based control designs are then developed and tested: a classical cascaded P/PI controller and a modern state feedback controller. The two controllers are compared and it is found that, whilst there are some performance differences, both meet the requirements for use in a redundantly actuated REPOINT switch

Hydrodeoxygenation of Furylmethane Oxygenates to Jet and Diesel Range Fuels: Probing the Reaction Network with Supported Palladium Catalyst and Hafnium Triflate Promoter

Catalytic hydrodeoxygenation of furylmethane oxygenates to high carbon branched chain jet and diesel fuel range alkanes under mild reaction conditions is a promising strategy for energy-efficient production of fuels with minimal C–C cracking to undesired products. Here, we report that a strong Lewis acidic promoter can overcome the energy barrier for furylmethane hydrodeoxygenation at lower temperature. Furan rings of furylmethanes are first hydrogenated to fully saturated cyclic ethers by a hydrogenation catalyst, which then undergo facile ring opening and deoxygenation by the promoter. A cyclic intermediate between ethereal O and the Lewis acidic metal center, assisted by the triflate ligand of the promoter, is formed in the ring-opening step. Probing the reaction pathway with symmetric single furan ring surrogate molecules suggests that the promoter is necessary for the ring opening. Deoxygenation of ring-opened oxygenates takes place more quickly for single furan ring surrogates than for the multiple furan ring furylmethanes. A maximum 97% jet fuel range alkanes with 93% selectivity in C₁₅H₃₂ and C₁₄H₃₀ is achieved from C₁₅-furylmethane under optimal conditions. The yield and selectivity of alkanes with desired carbon numbers can be tuned using furylmethanes with tailored carbon chains, furan numbers, and a carbon center that minimizes C–C cracking

LQR control applied to a novel track switch actuator

Existing railway track switches use open-loop actuation to enable trains to take different routes. A new type of railway track switch called REPOINT with a different electromechanical design to conventional track switches has been developed at Loughborough University that requires closed-loop control in order to perform its track switching function. This abstract proposes the use of a Linear Quadratic Regulator (LQR) controller to achieve track switch position control applied to the REPOINT switch. The results showed that the LQR controller enables successful switching of this novel railway track switch and satisfies the control requirements of a REPOINT track switch

Realisation of a novel functionally redundant actuation system for a railway track-switch

This paper focuses on modelling, control, realisation and performance analysis of a full-scale demonstrator for a novel railway track switch. For over a century, railway track switches (or points) have been allowing trains to safely change between routes. As they are safety-critical elements of the rail network, when they fail, the signalling system will prevent trains from using that route. This means poor reliability (or lack of availability) leads to significant delays and costs; hence there is huge interest from researchers and engineers in improving the overall reliability of track switches. This paper presents new results, which represent a meaningful first step toward a revolution in the way track switches are actuated. A “REPOINT-Light” railway track switch demonstrator is introduced which uses a new concept of locking to allow redundant actuation with three actuator bearers operating under closed-loop feedback control. The new concept, its control system and its mechanical viability are tested in experiments at the Great Central Railway in the UK. To support the design of the actuators and the control system, a dynamic simulation model is developed by co-simulation involving Simulink and Simpack. The experimental results presented are used to validate the models and the paper discusses how the models themselves are used as the vehicle for the design of feedback controllers. Virtual testing of the controllers in simulation is a vital step prior to the implementation and deployment of the controllers in the demonstrator switch. The major contribution of this work is demonstrating, for the first time at full scale on a real-world track switch, that it is possible to use one-out-of-three actuator redundancy to provide fault-tolerant operation of railway track switch

Improved Graphene-Oxide-Derived Carbon Sponge for Effective Hydrocarbon Absorption and C–C Coupling Reaction

Graphenic sponges have created tantamount interest due to their special affinity for absorbing a broad range of petroleum oils and solvents resulting from controllable surface wettability. A major challenge is to fabricate such materials with surface hydrophilicity coexisting with hydrophobicity. Herein, we report a scalable self-assembly of randomly oriented improved graphene oxide (IGO) sheets into a graphene oxide sponge (GOS-H) with uniform cylindrical shape via a hydrothermal method. Extensive characterization of GOS-H using Raman microspectroscopy, Raman imaging, X-ray photoelectron spectroscopy (XPS), and electron microscopic (SEM and HRTEM) techniques suggests the sponge surface is hydrophobic with some hydrophilic oxygen content and has defect sites and roughness associated with voids formation. These features and conformal C–O coating on the basal plans result in high-diesel-range alkanes absorption from pure alkanes as well as from alkane–water mixture, which could enable as-synthesized GOS-H as an efficient and inexpensive sponge for hydrocarbons cleaning from contaminated water. In addition, GOS-H exhibits high catalytic activity for C–C coupling reaction of biomass-derived furfural and 2-methylfuran under solventless conditions to produce jet fuel-ranged high-carbon oxygenates with a branched backbone

Preparation and Characterization of Aluminum Alkoxides Coordinated on salen-Type Ligands: Highly Stereoselective Ring-Opening Polymerization of <i>rac</i>-Lactide

A series of salen-type ligands (L¹H₂–L⁶H₂) with sterically bulky cumyl groups have been synthesized. Reaction of these ligands with AlMe₃ yields the mononuclear aluminum complexes [LAlMe] (<b>1</b>–<b>3</b>) or dinuclear species [L₂Al₂Me₄] (<b>4</b>–<b>6</b>), respectively. Further reaction of [LAlMe] (<b>1</b>–<b>3</b>) with benzyl alcohol produces [LAl­(OBn)] (<b>1a</b>–<b>3a</b>), respectively. Solid-state structural studies reveal that complexes <b>1a</b> and <b>2a</b> are mononuclear; however, complex <b>6</b> is a dinuclear species. Aluminum alkoxides <b>1a</b>–<b>3a</b> are highly stereoselective in the ROP of <i>rac</i>-lactide, producing polylactide (PLA) with 94–97% enantiomeric selectivity (<i>P</i>_m) at high conversion. Their high enantioselectivity leads to PLA with high <i>T</i>_m (205 °C). The polymerization of l-lactide by these complexes also shows good living features with narrow PDI values (<i>M</i>_w/<i>M</i>_n = 1.06–1.25) signaling less or no transesterification, which can be further verified by MALDI-TOF mass spectrometric analysis

Co-Crystals of a Salicylideneaniline: Photochromism Involving Planar Dihedral Angles

Co-Crystals of a Salicylideneaniline: Photochromism Involving Planar Dihedral Angle

Preparation and Characterization of Aluminum Alkoxides Coordinated on salen-Type Ligands: Highly Stereoselective Ring-Opening Polymerization of <i>rac</i>-Lactide

A series of salen-type ligands (L¹H₂–L⁶H₂) with sterically bulky cumyl groups have been synthesized. Reaction of these ligands with AlMe₃ yields the mononuclear aluminum complexes [LAlMe] (<b>1</b>–<b>3</b>) or dinuclear species [L₂Al₂Me₄] (<b>4</b>–<b>6</b>), respectively. Further reaction of [LAlMe] (<b>1</b>–<b>3</b>) with benzyl alcohol produces [LAl­(OBn)] (<b>1a</b>–<b>3a</b>), respectively. Solid-state structural studies reveal that complexes <b>1a</b> and <b>2a</b> are mononuclear; however, complex <b>6</b> is a dinuclear species. Aluminum alkoxides <b>1a</b>–<b>3a</b> are highly stereoselective in the ROP of <i>rac</i>-lactide, producing polylactide (PLA) with 94–97% enantiomeric selectivity (<i>P</i>_m) at high conversion. Their high enantioselectivity leads to PLA with high <i>T</i>_m (205 °C). The polymerization of l-lactide by these complexes also shows good living features with narrow PDI values (<i>M</i>_w/<i>M</i>_n = 1.06–1.25) signaling less or no transesterification, which can be further verified by MALDI-TOF mass spectrometric analysis

Self-Assembled TiO₂ Nanospheres By Using a Biopolymer as a Template and Its Optoelectronic Application

Self-assembled TiO₂ nanoparticulate materials with well-defined spherical morphologies were synthesized by using a biopolymer sodium alginate as a template under different synthesis conditions. Powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) techniques were used to characterize the TiO₂ nanoparticles. N₂ sorption analysis revealed the moderately good surface area (124.0 m² g^–1) and pore volume (0.44 cm³ g^–1) of these TiO₂ nanoparticles. The biopolymer templating pathway leads to good-quality self-assembled TiO₂ nanoparticles with dimensions of ca. 10–12 nm within the synthesis temperature range of 0–60 °C. These porous TiO₂ nanomaterials showed high photogenerated current in the presence of a dye (Rose Bengal), used as a sensitizer for several photo on/off cycles

Synthesis of the Insecticide Prothrin and Its Analogues from Biomass-Derived 5‑(Chloromethyl)furfural

Prothrin, a synthetic pyrethroid insecticide, was synthesized from the biomass-derived platform chemical 5-(chloromethyl)­furfural in six steps and overall 65% yield. Two structural analogues of prothrin were also prepared following the same synthetic approach. Preliminary testing of these furan-based pyrethroids against the yellow fever mosquito Aedes aegypti indicates promising insecticidal activities