Development of a test-rig for exploring optimal conditions of small unmanned aerial vehicle co-axial rotor systems

Due to the recent increase in development and use of co-axial rotor system at the scale of small UAVs a greater understanding of the performance variables that affect the co-axial propulsion system at low Reynolds number operation has become increasingly apparent when optimizing such systems. This paper focuses on and details the development and fabrication of a small UAV co-axial rotor system test-rig, and investigations into the optimal inter-rotor spacing range between contra-rotating rotors. An integrated test-rig has been specifically designed for the testing and analysis of commercial off-the-shelf (COTS) propellers and out-runner motors which are predominantly used in SUAV propulsion systems. The test-rig incorporates linear motion, yaw, force and other performance measurements, to help validate the identified core co-axial rotor system performance attributes. The co-axial test-rig was used to investigate co-axial rotor systems inter-rotor spacing which identified an optimum H/D ratio region of (0.41 – 0.65)

Worker silence in a turbulent neoliberal context: the case of mass privatisation of sugar factories in Turkey

Data Availability Statement: Due to the sensitive nature of the data, data set will be held by the authors.Copyright © 2023 The Authors. Silence in the context of work has different meanings across different settings. Turbulence induced by the privatisation of previously state-owned enterprises presents a curious setting to explore worker silence. Turning to worker silence in the process of mass privatisation of sugar factories in Turkey, we examine why workers remained silent while resenting privatisation. We reflect on the experiences and perceptions of workers in the privatisation of sugar factories in an unregulated neoliberal country, where macro-national and meso-institutional mechanisms enforce worker silence Drawing on 48 interviews with workers from sugar factories, we demonstrate that worker silence deepened in the process of privatisation. The study provides evidence that an unregulated form of neoliberalism worsens worker silence through three distinct mechanisms: dismissal of democratic demands, marketisation of everything and decline of solidarity. We extend these mechanisms with 13 different corresponding forms

Reconfigurable unmanned aerial vehicles.

Unmanned Aerial Vehicles (UAVs) have been developing dramatically due to wars and miniaturisation of technology, which has made the UAV industry a very lucrative business. Research organisations have been funded by various research committees or military groups to push UAV developments at a very fast pace. Although these UAVs are high in capability, they are limited to a single use application or mission. This paper will analyse current UAV systems to determine how the use of a novel reconfigurable UAV could benefit the end user

Investigating the use of the coanda effect to create novel unmanned aerial vehicles.

In recent years the demand for Unmanned Aerial Vehicles(UAV's) has increased rapidly across many different industries and they are used for various applications. Such systems have the ability to enter dangerous or inaccessible environments and allow vital information to be collected without human risk. In order to carry out a task, a UAV has to face many different challenges. This has led to the development of novel platforms that move away from traditional aircraft design in order to make them more capable. A good example of this type of craft is one which uses the Coanda Effect to assist propulsion. This effect was discovered in 1930 by Henri-Marie Coanda who found that if a thin film of air is directed over a curved body, then the air follows the curve. When used to propel a UAV, the Coanda Effect also entrains air from above and lowers the air pressure in this region, which in turn generates more lift. Many organizations have attempted to use this phenomenon to aid the lift of various unusual air vehicles

Developing a low-cost beer dispensing robotic system for the service industry

As the prices of commercially available electronic and mechanical components decrease, manufacturers such as Devantech and Revolution Education have made encoded motor controller systems and microcontrollers very accessible to engineers and designers. This has made it possible to design sophisticated robotic and mechatronic systems very rapidly and at relatively low cost. A recent project in the Autonomous Systems Lab at Middlesex University, UK was to design and build a small, automated, robotic bartender based around the 5 litre Heineken 'Draughtkeg' system, which is capable of patrolling a bar and dispensing beer when signalled to by a customer. Because the system was designed as a commercial product, design constraints focused on keeping the build cost down, and so electronic components were sourced from outside companies and interfaced with a bespoke chassis and custom mechanical parts designed and manufactured on site at the University. All the programming was conducted using the proprietary BASIC language, which is freely available from the PicAXE supplier at no cost. This paper will discuss the restrictions involved in building a robot chassis around 'off-theshelf' components, and the issues arising from making the human-machine interaction intuitive whilst only using low-cost ultrasonic sensors. Programming issues will also be discussed, such as the control of accuracy when interfacing a PicAXE microcontroller with a Devantech MD25 Motor Controller board. Public live testing of the system was conducted at the Kinetica Art Fair 2010 event in London and has since been picked up by websites such as Engadget.com and many others. Feedback on the system will be described, as well as the refinements made as a result of these tests

The future of battlefield micro air vehicle systems.

The most recent survey of Unmanned Aerial Vehicle (UAV) adoption rates shows that the area of small, man-portable systems (generally defined as Micro Air Vehicles or MAVs of maximum take-off weight between 1-5 kg) has one of the highest growth rates of any of the market sectors. There is a growing realisation by military planners that to win the insurgency wars of the present and future, forward units will have to operate within the close confines of urban conurbations and for prolonged periods of time without support. Real-time information and intelligence on enemy strength, dispositions and tactics is therefore essential for battlefield success

Porous materials show superhydrophobic to superhydrophilic switching

Switching between superhydrophobicity and superhydrophilicity in porous materials was predicted theoretically and demonstrated experimentally with the example of thermally induced contact angle change; tunability of this system was also demonstrated

Combined XPS and contact angle studies of ethylene vinyl acetate and polyvinyl acetate blends

Cataloged from PDF version of article.In this study, we prepared thin films by blending ethylene vinyl acetate copolymers (EVA) containing 12-33 (wt.%) vinyl acetate (VA) with polyvinyl acetate (PVAc) and high density polyethylene homopolymers. Large area micropatterns having controlled protrusion sizes were obtained by phase-separation especially for the PVAc/EVA-33 blends using dip coating. These surfaces were characterized by XPS and contact angle measurements. A reasonably linear relation was found between the VA content on the surface (wt.%) obtained from XPS analysis and the VA content in bulk especially for PVAc/EVA-33 blend surfaces. PE segments were more enriched on the surface than that of the bulk for pure EVA copolymer surfaces similar to previous reports and VA enrichment was found on the EVA/HDPE blend surfaces due to high molecular weight of HDPE. Water theta(e) decreased with the increase in the VA content on the blend surface due to the polarity of VA. A good agreement was obtained between gamma(-)(s) and atomic oxygen surface concentration with the increase of VA content. The applicability of Cassie-Baxter equation was tested and found that it gave consistent results with the experimental water contact angles for the case where VA content was lower than 55 wt.% in the bulk composition. (C) 2011 Elsevier B. V. All rights reserved

Topography driven spreading

Roughening a hydrophobic surface enhances its nonwetting properties into superhydrophobicity. For liquids other than water, roughness can induce a complete rollup of a droplet. However, topographic effects can also enhance partial wetting by a given liquid into complete wetting to create superwetting. In this work, a model system of spreading droplets of a nonvolatile liquid on surfaces having lithographically produced pillars is used to show that superwetting also modifies the dynamics of spreading. The edge speed-dynamic contact angle relation is shown to obey a simple power law, and such power laws are shown to apply to naturally occurring surfaces

Investigating the use of unmanned plant machinery on construction sites

The UK Construction Sector has been estimated to contribute 8% of the UK’s GDP [1]. The worldwide recession has forced construction companies to introduce and adopt cost saving measures to increase productivity. Several robotic building systems are in development for the Construction Sector such as the PERI’s Automatic Climbing System [2] and Brokk’s remote-controlled demolition machines [3], but there has been little implementation on live sites. Construction sites by their very nature are dynamically changing environments, so if human input was removed entirely, a robot would need a high level of awareness of the current state of the building project in order to navigate and carry out its tasks