6,111 research outputs found

    Towards Autonomous Selective Harvesting: A Review of Robot Perception, Robot Design, Motion Planning and Control

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    This paper provides an overview of the current state-of-the-art in selective harvesting robots (SHRs) and their potential for addressing the challenges of global food production. SHRs have the potential to increase productivity, reduce labour costs, and minimise food waste by selectively harvesting only ripe fruits and vegetables. The paper discusses the main components of SHRs, including perception, grasping, cutting, motion planning, and control. It also highlights the challenges in developing SHR technologies, particularly in the areas of robot design, motion planning and control. The paper also discusses the potential benefits of integrating AI and soft robots and data-driven methods to enhance the performance and robustness of SHR systems. Finally, the paper identifies several open research questions in the field and highlights the need for further research and development efforts to advance SHR technologies to meet the challenges of global food production. Overall, this paper provides a starting point for researchers and practitioners interested in developing SHRs and highlights the need for more research in this field.Comment: Preprint: to be appeared in Journal of Field Robotic

    Evaluation of image quality and reconstruction parameters in recent PET-CT and PET-MR systems

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    In this PhD dissertation, we propose to evaluate the impact of using different PET isotopes for the National Electrical Manufacturers Association (NEMA) tests performance evaluation of the GE Signa integrated PET/MR. The methods were divided into three closely related categories: NEMA performance measurements, system modelling and evaluation of the image quality of the state-of-the-art of clinical PET scanners. NEMA performance measurements for characterizing spatial resolution, sensitivity, image quality, the accuracy of attenuation and scatter corrections, and noise equivalent count rate (NECR) were performed using clinically relevant and commercially available radioisotopes. Then we modelled the GE Signa integrated PET/MR system using a realistic GATE Monte Carlo simulation and validated it with the result of the NEMA measurements (sensitivity and NECR). Next, the effect of the 3T MR field on the positron range was evaluated for F-18, C-11, O-15, N-13, Ga-68 and Rb-82. Finally, to evaluate the image quality of the state-of-the-art clinical PET scanners, a noise reduction study was performed using a Bayesian Penalized-Likelihood reconstruction algorithm on a time-of-flight PET/CT scanner to investigate whether and to what extent noise can be reduced. The outcome of this thesis will allow clinicians to reduce the PET dose which is especially relevant for young patients. Besides, the Monte Carlo simulation platform for PET/MR developed for this thesis will allow physicists and engineers to better understand and design integrated PET/MR systems

    Review of Methodologies to Assess Bridge Safety During and After Floods

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    This report summarizes a review of technologies used to monitor bridge scour with an emphasis on techniques appropriate for testing during and immediately after design flood conditions. The goal of this study is to identify potential technologies and strategies for Illinois Department of Transportation that may be used to enhance the reliability of bridge safety monitoring during floods from local to state levels. The research team conducted a literature review of technologies that have been explored by state departments of transportation (DOTs) and national agencies as well as state-of-the-art technologies that have not been extensively employed by DOTs. This review included informational interviews with representatives from DOTs and relevant industry organizations. Recommendations include considering (1) acquisition of tethered kneeboard or surf ski-mounted single-beam sonars for rapid deployment by local agencies, (2) acquisition of remote-controlled vessels mounted with single-beam and side-scan sonars for statewide deployment, (3) development of large-scale particle image velocimetry systems using remote-controlled drones for stream velocity and direction measurement during floods, (4) physical modeling to develop Illinois-specific hydrodynamic loading coefficients for Illinois bridges during flood conditions, and (5) development of holistic risk-based bridge assessment tools that incorporate structural, geotechnical, hydraulic, and scour measurements to provide rapid feedback for bridge closure decisions.IDOT-R27-SP50Ope

    Neural Natural Language Generation: A Survey on Multilinguality, Multimodality, Controllability and Learning

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    Developing artificial learning systems that can understand and generate natural language has been one of the long-standing goals of artificial intelligence. Recent decades have witnessed an impressive progress on both of these problems, giving rise to a new family of approaches. Especially, the advances in deep learning over the past couple of years have led to neural approaches to natural language generation (NLG). These methods combine generative language learning techniques with neural-networks based frameworks. With a wide range of applications in natural language processing, neural NLG (NNLG) is a new and fast growing field of research. In this state-of-the-art report, we investigate the recent developments and applications of NNLG in its full extent from a multidimensional view, covering critical perspectives such as multimodality, multilinguality, controllability and learning strategies. We summarize the fundamental building blocks of NNLG approaches from these aspects and provide detailed reviews of commonly used preprocessing steps and basic neural architectures. This report also focuses on the seminal applications of these NNLG models such as machine translation, description generation, automatic speech recognition, abstractive summarization, text simplification, question answering and generation, and dialogue generation. Finally, we conclude with a thorough discussion of the described frameworks by pointing out some open research directions.This work has been partially supported by the European Commission ICT COST Action “Multi-task, Multilingual, Multi-modal Language Generation” (CA18231). AE was supported by BAGEP 2021 Award of the Science Academy. EE was supported in part by TUBA GEBIP 2018 Award. BP is in in part funded by Independent Research Fund Denmark (DFF) grant 9063-00077B. IC has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 838188. EL is partly funded by Generalitat Valenciana and the Spanish Government throught projects PROMETEU/2018/089 and RTI2018-094649-B-I00, respectively. SMI is partly funded by UNIRI project uniri-drustv-18-20. GB is partly supported by the Ministry of Innovation and the National Research, Development and Innovation Office within the framework of the Hungarian Artificial Intelligence National Laboratory Programme. COT is partially funded by the Romanian Ministry of European Investments and Projects through the Competitiveness Operational Program (POC) project “HOLOTRAIN” (grant no. 29/221 ap2/07.04.2020, SMIS code: 129077) and by the German Academic Exchange Service (DAAD) through the project “AWAKEN: content-Aware and netWork-Aware faKE News mitigation” (grant no. 91809005). ESA is partially funded by the German Academic Exchange Service (DAAD) through the project “Deep-Learning Anomaly Detection for Human and Automated Users Behavior” (grant no. 91809358)

    Response of saline reservoir to different phaseCO₂-brine: experimental tests and image-based modelling

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    Geological CO₂ storage in saline rocks is a promising method for meeting the target of net zero emission and minimizing the anthropogenic CO₂ emitted into the earth’s atmosphere. Storage of CO₂ in saline rocks triggers CO₂-brine-rock interaction that alters the properties of the rock. Properties of rocks are very crucial for the integrity and efficiency of the storage process. Changes in properties of the reservoir rocks due to CO₂-brine-rock interaction must be well predicted, as some changes can reduce the storage integrity of the reservoir. Considering the thermodynamics, phase behavior, solubility of CO₂ in brine, and the variable pressure-temperature conditions of the reservoir, there will be undissolved CO₂ in a CO₂ storage reservoir alongside the brine for a long time, and there is a potential for phase evolution of the undissolved CO₂. The phase of CO₂ influence the CO₂-brine-rock interaction, different phaseCO₂-brine have a unique effect on the properties of the reservoir rocks, Therefore, this study evaluates the effect of four different phaseCO₂-brine reservoir states on the properties of reservoir rocks using experimental and image-based approach. Samples were saturated with the different phaseCO₂-brine, then subjected to reservoir conditions in a triaxial compression test. The representative element volume (REV)/representative element area (REA) for the rock samples was determined from processed digital images, and rock properties were evaluated using digital rock physics and rock image analysis techniques. This research has evaluated the effect of different phaseCO₂-brine on deformation rate and deformation behavior, bulk modulus, compressibility, strength, and stiffness as well as porosity and permeability of sample reservoir rocks. Changes in pore geometry properties, porosity, and permeability of the rocks in CO₂ storage conditions with different phaseCO₂-brine have been evaluated using digital rock physics techniques. Microscopic rock image analysis has been applied to provide evidence of changes in micro-fabric, the topology of minerals, and elemental composition of minerals in saline rocks resulting from different phaseCO₂-br that can exist in a saline CO₂ storage reservoir. It was seen that the properties of the reservoir that are most affected by the scCO₂-br state of the reservoir include secondary fatigue rate, bulk modulus, shear strength, change in the topology of minerals after saturation as well as change in shape and flatness of pore surfaces. The properties of the reservoir that is most affected by the gCO₂-br state of the reservoir include primary fatigue rate, change in permeability due to stress, change in porosity due to stress, and change topology of minerals due to stress. For all samples, the roundness and smoothness of grains as well as smoothness of pores increased after compression while the roundness of pores decreased. Change in elemental composition in rock minerals in CO₂-brine-rock interaction was seen to depend on the reactivity of the mineral with CO₂ and/or brine and the presence of brine accelerates such change. Carbon, oxygen, and silicon can be used as index minerals for elemental changes in a CO₂-brine-rock system. The result of this work can be applied to predicting the effect the different possible phases of CO₂ will have on the deformation, geomechanics indices, and storage integrity of giant CO₂ storage fields such as Sleipner, In Salah, etc

    The form and function of avian rictal bristles

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    Although mechanoreception is present throughout the animal kingdom, it is still relatively under-studied and poorly understood, especially in nocturnal birds. A particular type of facial feather, the rictal bristles, are thought to carry out a similar tactile function to mammalian whiskers, of which they superficially resemble. If they do, such a function could enhance foraging behaviour and facilitate obstacle avoidance, especially in dark, complex habitats. However, as rictal bristles are the least described of any feather, little is known about them. Therefore, this thesis characterises rictal bristle form and function by describing: i) bristle morphology and follicle anatomy, ii) the development of rictal bristles, and iii) the associated mechanosensory brain areas. It will also explore: iv) rictal bristle evolution and v) function. Results in this thesis demonstrated that rictal bristle morphology and the presence of mechanoreceptors around the follicle varied between species. Specifically, diurnal species did not have mechanoreceptors around their bristle follicles and had shorter bristles. Associated mechanosensory brain areas also varied between species, but there was no clear association between the neuroanatomy, rictal bristle morphology or foraging traits. Rictal bristles were absent in two species of altricial hatchlings, and only emerged after their eyes opened. Stimulation of the rictal region in these chicks led to behavioural feeding responses, especially coinciding with when chicks started to feed independently. Rictal bristle evolution underwent multiple events of disappearance and gain during avian evolution, and therefore, the presence and morphology of the rictal bristles also varied between orders, families and genera. Short rictal bristles with barbs at the base were likely to be present in the common ancestor of the phylogeny (108 mya). Rictal bristle presence and length were associated with nocturnality and foraging methods, and diet is also likely to be associated with rictal bristle length. Consequently, this thesis suggests that, in adult birds, rictal bristles are likely to act as facial tactile sensors in species that forage in low-light conditions in complex habitats. Rictal bristles are may, therefore, play a role in collision avoidance, foraging and eye protection. Species foraging in the daytime might have rictal bristles with a reduced tactile function. However, identifying rictal bristle function is challenging and demands further investigation. This thesis provides the first comparative description of avian rictal bristle form and function, and is an important foundation for further investigation of the sense of touch in birds

    High-Resolution Optical Imaging and Sensing Using Quantum Emitters in Hexagonal Boron-Nitride

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    Super-resolution microscopy has allowed optical imaging to reach resolutions well beyond the limit imposed by the diffraction of light. The advancement of super-resolution techniques is often an application-driven endeavor. However, progress in material science plays a central role too, as it allows for the synthesis and engineering of nanomaterials with the unique chemical and physical properties required to realize super-resolution imaging strategies. This aspect is the focus of this review. We show that quantum emitters in two-dimensional hexagonal boron nitride are proving to be excellent candidate systems for the realization of advanced high-resolution imaging techniques, and spin-based quantum sensing applications

    Moving object path prediction for traffic scenes

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    Accurate and efficient inference and prediction are important elements in intelligent systems. Knowing in advance the behaviour of an entity, such as the price of a product in the future, the weather in the next few days or the position of an object in the near future, is important for several applications like stock market, weather forecasting, robotics and more recently for autonomous vehicles. The aim of this work is to investigate and develop a novel approach for predicting the path of moving objects such as pedestrians and vehicles in the context of ego-cameras, like those mounted on a vehicle or a person. Due to the sequential nature of the data presented in paths, Recurrent Neural Networks (RNNs) are exploited, specifically Long Short-Term Memory Networks (LSTMs), due to their ability to process this type of data. LSTMs have the limitation of only predicting a single path per tracklet. Path prediction requires predicting with a level of uncertainty. Predicting multiple future paths instead of a single one is therefore a more realistic manner of approaching this task. In this work, predicting a set of future paths with associated uncertainty was achieved by combining LSTMs and MDNs. One of the objectives of this work is to include more information than simple position in the path prediction task, such as velocity of the ego vehicle and contextual information of the surroundings. Though the main interest of this work is on egocentric cameras experiments were also conducted using fixed cameras for a surveillance perspective. Two public datasets were used: KITTI and CityFlow. In summary, this thesis extends moving object path prediction methods in the context of traffic scenes for objects such as pedestrians, vehicles, cyclists

    Crafting Sustainability:A Study of Traditional Craft Practices in Central China

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    Today, traditional handmade crafts with a particularly local provenance are being appreciated and valued by consumers around the world. Noticeably, many designers have been involved in the re-examination and reassessment about the contemporary value and contribution of traditional craft practices and craft objects or artefacts. In China, in response to the UNESCO (the United Nations Educational, Scientific and Cultural Organisation) Convention for the Safeguarding of ICH (Intangible Culture Heritage), China has implemented a mechanism characterised as a combination of central initiative and local participation to create its own ICH and ICH Inheritors lists at multiple levels. Although much traditional heritage craft has been officially recognised as ICH, this does not necessarily mean that they are well-developed. This research aims to determine the relationship of traditional craft practices to sustainability in the Chinese context, to investigate and delineate the role of design in relation to Chinese craft revival activities, to identify sustainability-related issues, and to identify areas in which design can contribute to the long-term continuation of traditional craft practices. It draws upon the fields of craft and sustainability studies to provide a theoretical base for the research. The concept of ‘crafting sustainability’ is proposed, and four research propositions are formulated to explain the relationship of craft traditions to sustainability. Constructive methods are used in this research, including in-depth observations and thirty- two semi-structured interviews with a range of experts in craft fields. Primary data collected in three provinces of central China were coded and analysed. Analysis of the research helps validate the four research propositions developed from the literature. Also, their connections to place and people, significant values and ways in which craftspeople take their practices and conduct their businesses, and existing design interventions are interpreted from results. Overall, this study identifies 1) a variety of heritage making practices within the Chinese context; 2) a range of top-down support mechanisms provided by the Chinese government; 3) the relationships of craft makers and their practices/businesses to sustainability; 4) significant values that influence craft makers’ practices and their business; and 5) design opportunities for sustainability and viability

    Quantum computation in solid-state systems

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    In the last few years, as superconducting devices reached tens and later hundred qubits on a single chip, quantum computing has become a reality, tackling problems that would be prohibitively time-consuming even with the most powerful classical supercomputers. These early quantum computers (QC) are called noisy intermediate-scale quantum computers, since environmental noise cannot be efficiently counteracted in such small qubit arrays. While certain algorithms can indeed leverage the potential of hundreds of imperfect qubits, the great promises of quantum computing require perfect qubits that can be realized only in qubit arrays of much larger scales, using quantum error correction (QEC). Spin qubits in semiconductors are the only platform to date that has the potential of reaching such scales, paving way for fault-tolerant quantum computing. Qubits hosted in quantum dots (QDs) have dimensions of few tens of nanometers, facilitating the integration of potentially millions of qubit on a single chip. Especially compelling candidates are spin qubits in silicon nanostructures. With decades of experience coming from the semiconductor industry, silicon is one of the most studied elements with the prosperity of uniquely advanced manufacturing techniques. Electron spin qubits in silicon have immensely matured in the last few years reaching single- and two-qubit gate fidelities matching the error thresholds of QEC algorithms. However, the weak intrinsic spin-orbit interaction (SOI) in the conduction band necessitates the use of micromagnets to aid the all-electical qubit control. This additional complication presents new challenges in device design and fabrication. Hole spin qubits in silicon and germanium QDs, on the other hand, benefit from strong direct Rashba SOI accelerating qubit control speeds to several hundreds of megahertz, without the need to integrate additional elements in the device. In this thesis, we start with an introduction and a brief overview of the field, in Chapter 1, where we discuss the fundamental physics of hole quantum dots and how they satisfy the stringent prerequisites of quantum computing. Furthermore, we take a glimpse at the various components of scalable architectures and the requirements on the qubit architecture posed by QEC codes. In the subsequent chapters we address the question how the enhanced anisotropy and SOI affect two-qubit gates in hole QDs. In particular, we discuss exchange anisotropy due to orbital effects of the magnetic field and crystalline anisotropy in Chapter 2. We also confirm the emergence of the zero-field splitting of triplet states in hole QDs numerically, and develop an analytical model linking the effect to the cubic Rashba SOI in Chapter 3. This work presents the first theoretical model to explain this recently observed effect in hole QDs. Afterwards, in collaboration with the ZumbĂŒhllab, we decipher the strong spin-orbit effects in an experiment on Ge/Si nanowire QDs, where we also identify the strong g factor renormalization caused by enhanced SOI (Chapter 4). Furthermore, we study the tunability of SOI in silicon FinFET devices in Chapter 5, identifying sweet spots where the qubit lifetime is greatly prolonged. Finally, we study the prospects of coupling distant spin qubits by a chiral magnon mode localized at the edge of a two-dimensional ferromagnet in Chapter 6
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