3,329 research outputs found
Recent developments in 2D materials for energy harvesting applications
The ever-increasing demand for energy as a result of the growing interest in applications, such as the Internet of Things and wearable systems, etc, calls for the development of self-sustained energy harvesting solutions. In this regard, 2D materials have sparked enormous interest recently, due to their outstanding properties, such as ultra-thin geometry, high electromechanical coupling, large surface area to volume ratio, tunable band gap, transparency and flexibility. This has given rise to noteworthy advancements in energy harvesters such as triboelectric nanogenerators (TENGs), piezoelectric nanogenerators (PENGs) and photovoltaics based on 2D materials. This review introduces the properties of different 2D materials including graphene, transition metal dichalcogenides, MXenes, black phosphorus, hexagonal boron nitride, metal-organic frameworks and covalent-organic frameworks. A detailed discussion of recent developments in 2D materials-based PENG, TENG and photovoltaic devices is included. The review also considers the performance enhancement mechanism and importance of 2D materials in energy harvesting. Finally, the challenges and future perspectives are laid out to present future research directions for the further development and extension of 2D materials-based energy harvesters
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
ABC: Adaptive, Biomimetic, Configurable Robots for Smart Farms - From Cereal Phenotyping to Soft Fruit Harvesting
Currently, numerous factors, such as demographics, migration patterns, and economics, are leading to the critical labour shortage in low-skilled and physically demanding parts of agriculture. Thus, robotics can be developed for the agricultural sector to address these shortages. This study aims to develop an adaptive, biomimetic, and configurable modular robotics architecture that can be applied to multiple tasks (e.g., phenotyping, cutting, and picking), various crop varieties (e.g., wheat, strawberry, and tomato) and growing conditions. These robotic solutions cover the entire perception–action–decision-making loop targeting the phenotyping of cereals and harvesting fruits in a natural environment.
The primary contributions of this thesis are as follows. a) A high-throughput method for imaging field-grown wheat in three dimensions, along with an accompanying unsupervised measuring method for obtaining individual wheat spike data are presented. The unsupervised method analyses the 3D point cloud of each trial plot, containing hundreds of wheat spikes, and calculates the average size of the wheat spike and total spike volume per plot. Experimental results reveal that the proposed algorithm can effectively identify spikes from wheat crops and individual spikes. b) Unlike cereal, soft fruit is typically harvested by manual selection and picking. To enable robotic harvesting, the initial perception system uses conditional generative adversarial networks to identify ripe fruits using synthetic data. To determine whether the strawberry is surrounded by obstacles, a cluster complexity-based perception system is further developed to classify the harvesting complexity of ripe strawberries. c) Once the harvest-ready fruit is localised using point cloud data generated by a stereo camera, the platform’s action system can coordinate the arm to reach/cut the stem using the passive motion paradigm framework, as inspired by studies on neural control of movement in the brain. Results from field trials for strawberry detection, reaching/cutting the stem of the fruit with a mean error of less than 3 mm, and extension to analysing complex canopy structures/bimanual coordination (searching/picking) are presented.
Although this thesis focuses on strawberry harvesting, ongoing research is heading toward adapting the architecture to other crops. The agricultural food industry remains a labour-intensive sector with a low margin, and cost- and time-efficiency business model. The concepts presented herein can serve as a reference for future agricultural robots that are adaptive, biomimetic, and configurable
Strategies for Early Learners
Welcome to learning about how to effectively plan curriculum for young children. This textbook will address: • Developing curriculum through the planning cycle • Theories that inform what we know about how children learn and the best ways for teachers to support learning • The three components of developmentally appropriate practice • Importance and value of play and intentional teaching • Different models of curriculum • Process of lesson planning (documenting planned experiences for children) • Physical, temporal, and social environments that set the stage for children’s learning • Appropriate guidance techniques to support children’s behaviors as the self-regulation abilities mature. • Planning for preschool-aged children in specific domains including o Physical development o Language and literacy o Math o Science o Creative (the visual and performing arts) o Diversity (social science and history) o Health and safety • Making children’s learning visible through documentation and assessmenthttps://scholar.utc.edu/open-textbooks/1001/thumbnail.jp
Instrumentation and validation of a robotic cane for transportation and fall prevention in patients with affected mobility
Dissertação de mestrado integrado em Engenharia FÃsica, (especialização em Dispositivos, Microssistemas e Nanotecnologias)O ato de andar é conhecido por ser a forma primitiva de locomoção do ser humano, sendo que este
traz muitos benefÃcios que motivam um estilo de vida saudável e ativo. No entanto, há condições de saúde
que dificultam a realização da marcha, o que por consequência pode resultar num agravamento da saúde,
e adicionalmente, levar a um maior risco de quedas. Nesse sentido, o desenvolvimento de um sistema de
deteção e prevenção de quedas, integrado num dispositivo auxiliar de marcha, seria essencial para reduzir
estes eventos de quedas e melhorar a qualidade de vida das pessoas. Para ultrapassar estas necessidades
e limitações, esta dissertação tem como objetivo validar e instrumentar uma bengala robótica, denominada
Anti-fall Robotic Cane (ARCane), concebida para incorporar um sistema de deteção de quedas e um
mecanismo de atuação que possibilite a prevenção de quedas, ao mesmo tempo que assiste a marcha.
Para esse fim, foi realizada uma revisão do estado da arte em bengalas robóticas para adquirir um
conhecimento amplo e aprofundado dos componentes, mecanismos e estratégias utilizadas, bem como os
protocolos experimentais, principais resultados, limitações e desafios em dispositivos existentes.
Numa primeira fase, foi estipulado o objetivo de: (i) adaptar a missão do produto; (ii) estudar as
necessidades do consumidor; e (iii) atualizar as especificações alvo da ARCane, continuação do trabalho de
equipa, para obter um produto com design e engenharia compatÃvel com o mercado. Foi depois estabelecida
a arquitetura de hardware e discutidos os componentes a ser instrumentados na ARCane. Em seguida foram
realizados testes de interoperabilidade a fim de validar o funcionamento singular e coletivo dos componentes.
Relativamente ao controlo de movimento, foi desenvolvido um sistema inovador, de baixo custo e
intuitivo, capaz de detetar a intenção do movimento e de reconhecer as fases da marcha do utilizador. Esta
implementação foi validada com seis voluntários saudáveis que realizaram testes de marcha com a ARCane
para testar sua operabilidade num ambiente de contexto real. Obteve-se uma precisão de 97% e de 90% em
relação à deteção da intenção de movimento e ao reconhecimento da fase da marcha do utilizador.
Por fim, foi projetado um método de deteção de quedas e mecanismo de prevenção de quedas para
futura implementação na ARCane. Foi ainda proposta uma melhoria do método de deteção de quedas, de
modo a superar as limitações associadas, bem como a proposta de dispositivos de deteção a serem
implementados na ARCane para obter um sistema completo de deteção de quedas.The act of walking is known to be the primitive form of the human being, and it brings many benefits
that motivate a healthy and active lifestyle. However, there are health conditions that make walking difficult,
which, consequently, can result in worse health and, in addition, lead to a greater risk of falls. Thus, the
development of a fall detection and prevention system integrated with a walking aid would be essential to
reduce these fall events and improve people quality of life. To overcome these needs and limitations, this
dissertation aims to validate and instrument a cane-type robot, called Anti-fall Robotic Cane (ARCane),
designed to incorporate a fall detection system and an actuation mechanism that allow the prevention of
falls, while assisting the gait. Therefore, a State-of-the-Art review concerning robotic canes was carried out to
acquire a broad and in-depth knowledge of the used components, mechanisms and strategies, as well as
the experimental protocols, main results, limitations and challenges on existing devices.
On a first stage, it was set an objective to (i) enhance the product's mission statement; (ii) study the
consumer needs; and (iii) update the target specifications of the ARCane, extending teamwork, to obtain a
product with a market-compatible design and engineering that meets the needs and desires of the ARCane
users. It was then established the hardware architecture of the ARCane and discussed the electronic
components that will instrument the control, sensory, actuator and power units, being afterwards subjected
to interoperability tests to validate the singular and collective functioning of cane components altogether.
Regarding the motion control of robotic canes, an innovative, cost-effective and intuitive motion
control system was developed, providing user movement intention recognition, and identification of the user's
gait phases. This implementation was validated with six healthy volunteers who carried out gait trials with
the ARCane, in order to test its operability in a real context environment. An accuracy of 97% was achieved
for user motion intention recognition and 90% for user gait phase recognition, using the proposed motion
control system.
Finally, it was idealized a fall detection method and fall prevention mechanism for a future
implementation in the ARCane, based on methods applied to robotic canes in the literature. It was also
proposed an improvement of the fall detection method in order to overcome its associated limitations, as
well as detection devices to be implemented into the ARCane to achieve a complete fall detection system
Impacts of insecticide exposure on bumblebee behaviour in a warming world
With ongoing agricultural land-use intensification and climate change, important functional groups of organisms, including insect pollinators, are being simultaneously and ubiquitously exposed to both pesticides and changing temperatures. Given the notable ongoing declines in insect pollinators, understanding how these stressors affect aspects of key functional behaviours underpinning fitness and pollination service provision is of global ecological and economic importance. Importantly, a critical but understudied step in evaluating pesticide risk is to understand how environmental temperature modulates pesticide effects on these behaviours. Through empirical lab experiments on a key wild pollinator, the bumblebee Bombus terrestris, I quantified the temperature dependent effects of insecticide exposure on individual flight and general mobility. Neonicotinoid exposure dramatically impaired flight motivation and endurance, and these same performance traits were also found to be highly sensitive to environmental temperature. However, the effect of neonicotinoid exposure varied depending on post-exposure temperature, with impacts on flight being enhanced under warmer conditions and impacts on food consumption, walking, and general responsiveness being enhanced under cooler conditions. The hazard posed by insecticides to insect pollinators may therefore vary both temporally and spatially, with impairment to flight and mobility traits likely constraining colony foraging potential and diminishing pollination service capabilities. Interestingly, the same effects were not seen across a different class of insecticide, with the new to market sulfoximine insecticide, sulfoxaflor, showing no detectable effect on any measure of mobility regardless of temperature when applied at comparable concentrations. The findings of this thesis suggest both the choice of insecticide and timing of exposure need to be considered in farming practices. Additionally, my findings provide crucial information for advising insecticide risk assessment protocols, developing mitigative and conservation action, and above all understanding which possible climate regions in the world insect pollinators are most at risk from insecticide exposure.Open Acces
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Soft actuator and agile soft robot
Robots play an important part in many aspects of our society by doing repetitive, dangerous, or precision tasks. Most existing robots are made of rigid components, which lack passive compliance and pose a challenge in adapting to the environment and safe human-robot interaction. Rigid robots may be equipped with sensors and programmed with proprioceptive feedback control to achieve active compliance, but this may fail in the event of unforeseen situations or sensor failure.
In contrast, animals have evolved flexible or soft body parts to help them adapt to changing environments. Soft robotics is an emerging field in robotics, drawing inspiration from nature by integrating soft material into the actuator and mechanical design. With the inclusion of soft material, soft actuators and robots can deform actively/passively, making it possible to sense, absorb impact, and adapt to its environment with deformation. However, while soft actuators/robots have superior properties to rigid ones, they are often challenging to manufacture and control precisely. In addition, they may suffer from slow speed and material degradation. Thus, in this thesis, we aim to address the issues in developing high-performance soft actuators and soft robots.
The thesis is divided into two parts. In the first part, we focus on improving the manufacturability and performance of a self-contained soft actuator originated in the Creative Machines Lab. The soft actuator is composed of a cured silicone-ethanol mixture embedded with heating coils. When the coils are electrically actuated, ethanol trapped inside undergoes liquid-vapor transitions, and thus the actuator undergoes extreme volume change. While this actuator exhibits high strain and high stress, it is very slow to actuate, has limited life cycles, and requires molds to manufacture.
The first part of the thesis will address these issues. Specifically, in chapter 2, we discuss using multi-material 3D printing to automate the manufacturing of silicone-ethanol composite. In chapter 3, we discuss using laser-cut flexible Kirigami patterns to improve the manufacturability of its heating element. Chapter 4 characterizes its actuation profile and addresses improvements to the thermal conductivity by infusing thermally conductive fillers.
Soft actuation is an actively researched area; however, many high-performance soft actuators are challenging to manufacture and thus are less accessible to the general robotics community. Conventional actuators such as electric motors are widely available but lack flexibility. Therefore, the second part of the thesis aims at combining rigid motors with soft materials to design and control high-performance hybrid soft robots. Simulation is a good way to evaluate and optimize robot design and control. However, existing simulators that support motor-driven soft robots have limited features. Chapter 5 discusses this issue and presents a physically based real-time soft robot simulator capable of simulating motor-driven soft robots. In addition, chapter 5 presents the design and control of a 3D printed hybrid soft quadruped robot. Chapter 6 presents the design and control of a 3D printed hybrid soft humanoid robot.
The two parts of the thesis aim to improve aspects in soft actuators and soft robots. In conclusion, we summarize the lessons learned in developing soft actuators/robots and new possibilities and challenges for advancing soft robotics research
Development of a light-sheet fluorescence microscope employing an ALPAO deformable mirror to achieve video-rate remote refocusing and volumetric imaging.
There are numerous situations in microscopy where it is desirable to remotely refocus a microscope employing a high numerical aperture (NA) objective lens. This thesis describes the characterisation,
development and implementation of an Alpao membrane deformable mirror-based system to achieve this goal for a light-sheet fluorescence microscope (LSFM).
The Alpao deformable mirror (DM) DM97-15 used is this work has 97 actuators and was sufficiently
fast to perform refocus sweeps at 25 Hz and faster. However, a known issue with using Alpao
deformable mirrors in open-loop mode is that they exhibit viscoelastic creep and temperature-
dependent variations in the mirror response. The effect of visco-elastic creep was reduced by
ensuring that the mirror profile was on average constant on timescales shorter than the characteristic time of the visco-elastic creep. The thermal effect was managed by ensuring that the electrical power delivered to the actuators was constant prior to optimisation and use. This was achieved by ensuring that the frequency and amplitude of oscillation of the mirror was constant prior to optimisation, so that it reached a thermal steady state, was approximately constant during optimisation and constant during use.
The image-based optimisation procedure employed used an estimate of the Strehl ratio of the optical system calculated from an image of an array of 1 μm diameter holes. The optimisation procedure
included optimising the amount of high-NA defocus and the Zernike modes from Noll indices 4 to 24. The system was tested at 26.3 refocus sweeps per second over a refocus range of -50 to 50 μm with a 40x/0.85 air objective and a 40x/0.80 water immersion objective. The air objective enabled a mean Strehl metric of more than 0.6 over a lateral field of view of 200x200 microns and for a refocus range of 45 microns. The water objective achieved a mean Strehl metric of more than 0.6 over a lateral field of view of 200x200 microns over a larger refocus range of 77 microns.
The DM-based refocusing system was then incorporated into a LSFM setup. The spatial resolution of the system was characterised using fluorescent beads imaged volumetrically at 26.3 volumes per second. The performance of the system was also demonstrated for imaging fluorescence pollen grain samples.Open Acces
The role of language and sensorimotor information in memory for concepts
The linguistic-simulation approach to conceptual representations has been investigated for some time, but the role of language and sensorimotor information in memory for objects and words, both short- and long-term, has not been examined in detail. In the present thesis, I look at the interplay of sensorimotor and linguistic information in conceptual knowledge and examine which aspects of concepts are represented in memory tasks. I also aim to establish the role of consciously accessing conceptual information in word recognition and memory. The thesis includes three self-contained papers which show that the conceptual system relies on linguistic or sensorimotor information according to task demands. In the paper in Chapter 4, I examined the linguistic bootstrapping hypothesis, which postulates that linguistic labels can serve as placeholders for complex sensorimotor representations. I tested the capacity of working memory for object concepts using an articulatory suppression task to block access to language. I found that working memory capacity for contextually related object concepts when relying on sensorimotor information is higher than the traditionally reported capacity of 3-4 for simple shapes or colours. Additionally, when linguistic labels are available to deputise for complex sensorimotor information, the capacity further increases by up to two object concepts. In Chapters 5 and 6, I examined the content of conceptual information stored in long-term memory, and the role of sensorimotor simulation and consciously available information in word recognition and word memory. The studies revealed that consciously generated imagery is not reliably measured, and moreover, it does not contribute to word recognition in a consistent manner. Some of the effects of imageability found in the literature can be explained or subsumed by sensorimotor information, which is not fully available through conscious awareness. However, conscious imagery may be a useful strategy to support word memory when trying to explicitly remember words. The thesis demonstrates that both linguistic labels and sensorimotor information contribute to memory for concepts. The way a concept is represented in different tasks varies depending on task demands. Linguistic information is used to circumvent resource capacity limits, while sensorimotor information guides behaviour by providing more detailed information about the meaning of concepts, and our previous experience with them
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