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Interaction-aware and driving style-aware trajectory prediction for heterogeneous vehicles in mixed traffic environment
No full textTrajectory prediction (TP) of surrounding vehicles (SVs) is crucial for autonomous vehicles (AVs) to understand traffic situations and achieve safe-efficient decision-making and motion planning. However, different drivers’ personalized driving preferences will bring uncertainties for long-term TP in the mixed traffic environment. To this end, this paper proposes a TP model with interaction awareness and driving style awareness for long-term TP of heterogeneous SVs. Firstly, the driving conditions in the highD dataset are distinguished, and three different driving styles of the vehicle in the car-following condition are obtained based on an unsupervised clustering algorithm. Then, an encoder-decoder architecture based on novel lane attention and multi-head attention mechanisms is proposed, where the encoder analyzes historical trajectory patterns and the decoder generates future trajectory sequences. The lane attention mechanism enhances the spatial perception capability of vehicles towards the target lane, and the multi-head attention mechanism extracts high-dimensional global interaction information about the heterogeneous vehicle group (HVG) surrounding the target vehicle (TV). Experimental results show that the proposed model outperforms state-of-the-art models in root-mean-square-error (RMSE) for long-term TP and exhibits excellent adaptability to diverse driving tasks. Moreover, this paper verifies that the driving style topology within the HVG has multiple impacts on the TP accuracy of the TV.This work was supported by National Natural Science Foundation of China under Grants 52372410 and 52025121; State Key Laboratory of Intelligent Green Vehicle and Mobility under Project No. KFY2415; and SEU Innovation Capability Enhancement Plan for Doctoral Students under Grant CXJH SEU 25062.IEEE Transactions on Intelligent Transportation System
Conceptual design methodologies appropriate to electric vertical take-off and landing aircraft in urban air mobility
Get PDFStockford, Jack - Associate SupervisorThis project aims to investigate the current state of conceptual design issues
related to electric Vertical Take-off and Landing aircraft (eVTOL) in Urban Air
Mobility (UAM). The thesis seeks to develop design methodologies appropriate
for eVTOLs and explore the design space for various configurations, including
Vectored Thrust, Lift+Cruise, and Multicopter concepts. This project developed a
design model for eVTOL within the multi-disciplinary design analysis and
optimization environment - GENUS at Cranfield University. The GENUS
framework integrates various aerodynamic analysis tools, efficient geometric
parameterization methods, semi-empirical mass breakdown models, and
effective boundary layer ingestion analysis models. This enables comprehensive
conceptual design and design space exploration for novel aircraft, considering
real-world considerations. In this project, optimization and comparison are
conducted across more than 200 cases involving different aircraft configurations,
passenger capacities, battery capacities, cruising speeds, and ranges.
Multicopter configurations are suited for short-range, low-speed flights due to the
simpler structure and rotor system, despite limitations in range and speed
imposed by disk loading and propeller efficiency. Vectored Thrust configurations
are suitable for long-range and high-speed flights due to the high lift-to-drag ratio.
The Lift + Cruise configuration is versatile due to the combination of lift rotors and
propulsion propellers, resulting in higher efficiency for both cruising and hovering.
Battery technology is a crucial factor in eVTOL design. With a battery energy
density of 300 Wh/kg, the battery weight accounts for approximately 60% of the
total weight for a 2-passenger eVTOL undertaking a 200-mile mission. However,
at a battery energy density of 900 Wh/kg, the battery weight for a 20-passenger
eVTOL performing a 200-mile mission reduces to around 15-20%.PhD in Aerospac
Analysis and experiment of a VTOL flapping wing rotor micro aircraft
Get PDFWhidborne, James F. - Associate SupervisorThis thesis presents an in-depth study of the aerodynamic and structural analysis
of a novel bio-inspired flapping wing rotor (FWR) micro aerial vehicle (MAV)
capable of vertical take-off and landing. The FWR is characterized by a
combination of active flapping motion with passive rotation of the wings in an
asymmetric installation to produce a significantly higher lift coefficient than
traditional flapping wings. This research is aimed at further enhancing the FWR
MAV’s efficiency and aerodynamic performance with flight capability and stability.
This is approached by improving the FWR kinematics of motion and mechanism
through analytical, numerical simulation, and experimental methods.
In the first step, an efficient wing rotation method that allowed a small angle of
attack in the downstroke and a larger one in the upstroke was considered. A novel
Passive Pitching Angle Variation (PPAV) device, replacing traditional active
rotation, was developed and integrated into the flapping mechanism. Using a
high-speed camera and a load cell device for experiments, the PPAV-integrated
FWR demonstrated a significant increase in aerodynamic efficiency compared to
its constant pitch angle counterpart.
In the second step, the study focused on enhancing FWR-MAV power efficiency
by integrating springs into the mechanism, thereby reducing input power due to
the counterbalance between elastic and inertia forces. Numerical analysis and
experimentation with an FWR test model were conducted to simulate and
measure the resultant kinematics of motion and forces. Specific emphasis was
placed on the influence of spring stiffness on the FWR’s aerodynamic and power
efficiency. This led to the development of a PPAV-integrated FWR model capable
of remote-controlled vertical take-off and hovering.
In the third step, the study explored wing flexibility’s impact on FWR’s unsteady
aerodynamics using Fluid-Structure Interaction (FSI) analysis and experiments.
A novel dragonfly-like wing with a curved sweep-back wingtip demonstrated
aerodynamic benefits. The study elucidates the mechanism of wing bending
deformation linked to vortex variation, implying that optimal spanwise variable
stiffness can enhance lift and power efficiency. Employing flexible wings, the
FWR model’s lift significantly increased from 25 g to 51 g, highlighting enhanced
efficiency and payload capacity.
The study finally explored the FWR-MAV's flight performance and efficiency,
including VTOL and forward flight. It proposed a transformable MAV concept from
VTOL FWR mode to a bird-like flapping-wing mode in forward flight. A test model
was built to validate the transformation concept. Using MSC.ADAMS/Simulink co-
simulations and a quasi-steady aerodynamic method, the flights of the FWR
model in both flight modes were simulated and stability was demonstrated.PhD in Aerospac
Fire detection automation in search drones using a modified DeepLabv3+ approach
Get PDFDrones have become a key component in current search and rescue applications such as wildfire detection. The accurate detection of fire in forests plays a crucial global factor to reduce environmental damage and the preservation of wildlife. Current fire detection systems combine the merits of expert-learning systems and light-weight deep learning architectures. The key idea is to introduce color-based rules to identify potential fire pixels and create the associated mask that feeds a light-weight convolutional neural network (CNN) for image segmentation. However, expert learning systems are not robust and suffer of cognitive bias that induce a high number of false positives. In addition, CNN-based architectures cannot capture long-range dependencies reducing the segmentation fidelity. To overcome these gaps, this paper proposes a light weight deep learning (DL) architecture for fire segmentation. The approach is inspired in the Deeplabv3+ architecture for image segmentation. The novelty lies in the incorporation of vision transformers that heavily reduces the model complexity and avoid the usage of color-based rules. Experiments are conducted using open-access fire datasets. The results demonstrate competitive performance and highlight its potential use in drones applications.We would like to thank Haydn Thompson from Thhink in sponsoring this project. This work was supported by the Engineering and Physical Sciences Research Council under Grant EP/V026763/1.2024 IEEE International Smart Cities Conference (ISC2
Results and data used to validate the coupling of the Navier-Stokes and the Newton-Euler equations via the DF-IBM implementation against previous numerical data
No full textThe direct-forcing immersed boundary method (DF-IBM) algorithm previously developed by the authors is extended by coupling the Navier-Stokes equations with the Newton-Euler equations for rigid body dynamics within the DF-IBM framework. This coupling broadens the applicability of the previous development, from stationary or prescribed motion to flow-induced (free) motion cases. To address fluid-rigid body interactions under a partitioned approach, an implicit coupling algorithm is developed to handle strongly coupled interface conditions. Stability and convergence issues, particularly stemming from critical solid-fluid density ratios and from the rigid body approximation of internal mass effects in rotational dynamics, are mitigated using a fixed relaxation technique for the rigid body kinematics to ensure numerical robustness. Additionally, the proposed algorithm leverages the previously developed DF-IBM formulation and the predictor-corrector strategy of the \hl{pressure implicit with splitting of operators (PISO)} algorithm by omitting the momentum predictor step and the costly corrector loops from the implicit iterations. The method is validated against several benchmark cases, demonstrating robustness, stability, and efficiency in capturing complex fluid-rigid body interactions across a range of challenging scenariosEngineering and Physical Sciences Research Council (EPSRC
Chapter 43: Materials analysis of ceramics
Get PDFThe versatility and geological ubiquity of clay materials have meant that humans have adapted it to a wide range of different purposes, from building materials to tools for storage, transport, cooking, and eating. Archaeological ceramics range from mundane everyday wares to exquisite pieces of craftsmanship available only to the highest elites. Ceramic ethnoarchaeology has documented a wide range of approaches to clay processing, involving the removal and addition of constituents, as well as homogenization and transformation of raw materials through ageing or ‘souring’ of clays to improve their properties. Most laboratory analyses of ceramic materials can be grouped into three broad categories: compositional analyses, microstructural analyses, and macrostructural analyses. The presence of optical activity in the clay groundmass, when viewed in thin section under crosspolars, suggests a firing process that preserved the crystalline structure of clay minerals and did not result in extensive vitrification
Beyond survival …
Get PDFThe purpose of this closing paper is to “draw threads” from the collection of papers presented in this Special Issue, with the aim of exploring the defence industrialisation experiences of small and medium powers. Structurally, the paper begins by examining the challenges Tier Two and Three nations face in developing and sustaining defence industries. Attention then switches to assessing the coping strategies these countries adopt in seeking to overcome the limitations imposed by constricted scale and defence economic infrastructure. Government has an important role to play in addressing trade-offs linked to the autonomy, dependence, and efficiency trilemma. The aim is to ensure that the required degree of indigenous defence industrial capacity offers an acceptable level of sovereignty and manufacturing efficiency that is also affordable. The final section speculates on the future defence industrial opportunities and threats Tier Two and Three states are likely to confront. Whatever the future holds, there is a sense from the case studies presented that small and medium powers can survive the constraints of relative smallness and prosper.Defence Studie
Securing defense critical minerals: challenges and U.S. strategic responses in an evolving geopolitical landscape
Get PDFThe growing dependence on critical minerals (CMs) for advanced military technologies presents significant and escalating challenges for the United States (U.S.) and its allies. As global competition intensifies and supply chains remain vulnerable to geopolitical disruptions, securing a stable supply of defense CMs has become a top strategic priority. This article identifies key defense CMs, emphasizing their dual-use nature and the risks posed by reliance on adversarial nations such as China and Russia. It analyzes U.S. strategic responses and offers recommendations for balancing national security, economic feasibility, and sustainability in managing defense CM supply chains using a comprehensive approach.Comparative Strateg
Outer Space Treaty (OST) - blueprint for “peaceful uses” or pitfall for future conflict?
Get PDFThe Outer Space Treaty (OST) was enacted in 1967 in the context of the ‘Space Race’ between the US and the USSR, accelerated following the USSR’s launch of Sputnik in 1957. In recent years, rapid development of technology has enabled significant increase in the extent of activities in Space, resulting in many more States getting involved in the Space sector and the opening up of commercial activities that include the private sector. Thus, there has been a corresponding increase in the possibility of conflict arising from activities in Space, whether intentional or by mistake. Although there have been some initiatives in working on codes and
guidance in the conduct of activities in Space, the position in key areas of conduct, accountability and enforcement has still to be clarified. This has important implications on the Laws of Armed Conflict (LOAC) given the increased risk of conflict and the particular characteristics of Space. This study will evaluate the “peaceful uses” wording in the OST through an International Relations (IR) lens and drawing on Comparative Adaptive Systems theory as to its context and subsequent practice.Defence and Security Doctoral Symposia 2024 (DSDS24
Editorial: Micro/nano devices and technologies for neural science and medical applications
Get PDFResearch on micro/nano devices and technologies represents a significant Frontier at the intersection of information science and life sciences, holding substantial strategic importance and promising application prospects in the fields of neural science and medical applications (Liu et al., 2020). With the rapid advancement of micro/nano processing technology, innovative intelligent, miniaturized, and integrated devices are emerging. These devices offer distinct advantages in detection and regulation. Notably, integrating micro/nano devices with neural science and clinical medicine can address scientific frontiers while fostering new research hotspots.This work was sponsored by STI 2030 – Major Projects 2021ZD0201603, the Joint Foundation Programme of the Chinese Academy of Sciences (8091A170201), National Natural Science Foundation of China (No. T2293730, T2293731, T2293734, 62,471,291, 62,121,003, 61,960,206,012, 62,333,020 and 62,171,434), the National Key Research and Development Program of China (No. 2022YFC2402501, 2022YFB3205602).Frontiers in Bioengineering and Biotechnolog