20505 research outputs found
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Mechanical characterization of a 3D large strain zero Poisson’s ratio helical metamaterial
No full textSupplementary information The online version contains supplementary material available at: https://doi.org/10.1038/s43246-025-00832-0.Mechanical metamaterials with zero Poisson’s ratio (ZPR) offer unique advantages in applications requiring dimensional stability under large deformations. Here we present a three-dimensional, large strain ZPR metamaterial composed of shape-optimized helical ligaments arranged in a hierarchical lattice. The design reduces stress concentrations at the joints and supports substantial elastic deformation in tension, compression and shear, while maintaining orthotropic, decoupled stress-strain behaviour. Finite element analyses assess homogenized properties, buckling behaviour, and vibrational modes through the analysis of the phononic band gaps, showing low normalized Young’s modulus and strain-invariant Poisson’s ratios. We further examine the influence of ligament cross-sectional diameter and the effect of different base materials on stiffness and strain range. Experimental tests on 3D-printed specimens confirm the predicted ZPR behavior and deformation capacity. The metamaterial’s elastic isotropy, fatigue resistance, and tailorable stiffness make it suitable for multifunctional applications including adaptive actuators, morphing structures, and energy-absorbing systems.Communications Material
A tandem cubic DNA nanostructures cell membrane surface sensing platform for in situ monitoring of multiple cytotoxicity-related biomarkers
No full textEmerging organic pollutants (EOPs) are considered to exhibit extensive toxicity to the human body. However, monitoring of this toxicological process is hampered by the shortage of suitable methods to track endogenous biochemical factors at the living cell level. To solve this technical challenge, a cell surface fluorescent sensing platform using tandem cubic DNA nanostructures (tCDNs) as the main architecture is developed in this work. With the precise assembly of several prefabricated DNA wireframe modules, a set of linear nanosuperstructures can be efficiently hydrophobic anchored to the cell membrane surface. Furthermore, two different aptamer-based fluorescence recognition elements targeting adenosine triphosphate (ATP) and dopamine (DA) can be modified on top of tCDNs in an equidistant arrangement, serving as a core component for monitoring endogenous cellular biochemical factors. As a typical example, we used tetrabromobisphenol A bis(2-hydroxyethyl ether) (TBBPA-BHEE)-induced living cells as a toxic effect system to monitor the release of endogenous ATP and DA in a direct visualization manner. On this basis, the correlation between the concentrations of these two endogenous biochemical factors (ATP and DA) and different TBBPA-BHEE exposure conditions was explored. We believe that this work can provide a robust and promising tool for studying the cellular toxicological mechanisms caused by pollutants.This work was supported by the National Natural Science Foundation of China (Grants No. 22176075 and 22476072) and the Jiangsu Collaborative Innovation Center of Technology and Material of Water Treatment.Analytical Chemistr
Meta-hierarchical reinforcement learning based beamforming for near-field multi-user communications
No full textExtremely Large Antenna Array Systems (ELAAs) promise to provide ultra-high data rates for multi-user 6G Communications, leveraging massive antenna elements to enhance spatial diversity and spectral efficiency. Unfortunately, considering the propagation of spherical waves in ELAAs, near-field beamforming suffers from substantial performance degradation, diminished spatial focusing precision, considerable computational overhead, and increased system costs. To address these challenges, this paper develops an intelligent hybrid beamforming scheme to empower near-field multi-user THz communications with meta-hierarchical reinforcement learning (MHRL). On the one hand, a novel codebook is designed with Hierarchical Deep Q Network (H-DQN), dramatically releasing the potential of near-field beamforming in ELAAs. To explain the availability of our codebook, the quantization bound is analyzed along with the corresponding computational complexity. On the other hand, we further develop a meta-beamforming framework by integrating our intelligent codebook to meta-reinforcement learning (MRL)-based hybrid beamformer, accelerating the CSI acquisition for multi-user communication. For deep investigation, the rate loss of our scheme is calculated against the ideal continuous beamformer, which reveals that the quantization error has been properly bounded. Simulation results show that the proposed algorithm can efficiently manage the near-field beam with higher beamforming gain, and the proposed beamforming framework exhibits improved spectral efficiency, as well as increased robustness to ELAAs.This work is supported by Future Aviation Security Solutions Industrial PHD Partnership (FASS IPP) under grant P14868IEEE Transactions on Wireless Communication
Forgotten fibre waste: mycoremediation and recycling of used absorbent hygiene products
No full textBeyond clothing, end-of-life technical textiles and nonwoven products are an additional source of fibre-based waste and environmental impact. Absorbent Hygiene Products (AHPs), i.e. single use, disposable diapers (nappies), adult incontinence and menstrual products, play an important role in supporting the personal hygiene and wellbeing of millions of people worldwide, but their disposal presents considerable waste management and environmental challenges due to their biological contamination, as well as mixed fibre and polymer composition. Despite high rates of consumption, used AHPs remain one of the hardest waste streams to recycle, and most are incinerated or landfilled. Internationally, very little used AHP recycling infrastructure exists, and generating high-value outputs from such waste is highly challenging, mainly due to its multifaceted nature. This review evaluates the potential for an alternative biotechnological approach to recycling based on mycoremediation and biocatalysis of used AHPs (containing cellulose, superabsorbent polymers and synthetic polymers) harnessing fungi to valorise the cellulosic and plastic components of the waste. We focus on the synergistic integration of mycoremediation and precision fermentation techniques as part of a biorefinery model to yield valuable material outputs from used AHPs, such as industrial chemicals and fibre-forming biodegradable polymers for industrial applications, as a basis for new circular economies.The authors RPS and VK gratefully acknowledge the support of Research England for funding the Magan Centre of Applied Mycology (MCAM) at Cranfield University, UK.Resources, Conservation and Recyclin
Building trust in autonomous aerial systems: a review of hardware-rooted trust mechanisms
No full textUnmanned aerial vehicles (UAVs) are redefining both civilian and defense operations, with swarm-based architectures unlocking unprecedented scalability and autonomy. However, these advancements introduce critical security challenges, particularly in location verification and authentication. This review provides a comprehensive synthesis of hardware security primitives (HSPs)—including Physical Unclonable Functions (PUFs), Trusted Platform Modules (TPMs), and blockchain-integrated frameworks—as foundational enablers of trust in UAV ecosystems. We systematically analyze communication architectures, cybersecurity vulnerabilities, and deployment constraints, followed by a comparative evaluation of HSP-based techniques in terms of energy efficiency, scalability, and operational resilience. The review further identifies unresolved research gaps and highlights transformative trends such as AI-augmented environmental PUFs, post-quantum secure primitives, and RISC-V-based secure control systems. By bridging current limitations with emerging innovations, this work underscores the pivotal role of hardware-rooted security in shaping the next generation of autonomous aerial networks.Future Interne
An overview of the hydrogen value chain in energy transitioning economies: a focus on India
No full textIndia's energy sector is undergoing a major transformation as the nation targets energy independence by 2047 and net-zero emissions by 2070. With a high dependency on energy imports, a strategic shift toward renewable energy and decarbonisation is crucial. Hydrogen has emerged as a promising solution to address energy storage and sustainability challenges, prompting emerging countries to develop strong hydrogen infrastructures. This paper examines various methods involved in the hydrogen value chain, from production to utilisation, from the perspective of transitioning economies. By identifying key parameters and existing gaps, this paper aims to support policymakers and stakeholders in designing effective strategies to accelerate the development of a sustainable and secure hydrogen economy. India currently relies on carbon-intensive hydrogen from fossil fuels. Green hydrogen faces high costs and infrastructure gaps. Despite storage and safety concerns, hydrogen shows strong potential for clean energy and industry transformation.International Journal of Hydrogen Energ
Investigation of plasma transferred arc dynamic effects in wire + arc additive manufacturing
No full textDing, Jialuo - Associate SupervisorThis investigation focuses on the effect of plasma transferred arc (PTA) parameters and torch geometry on arc pressure to characterise the soft plasma process and the avoidance of keyhole defect formation. A measured arc pressure comparison with gas tungsten arc (GTA) was also undertaken. The objective being to minimise arc pressure, reducing any depression of the melt-pool and thereby its effects on bead geometry. Both are essential for the wire + arc additive manufacture (WAAM) process. The research approach includes experimental measurement of arc pressure for combinations of torch nozzle and electrode geometries and process variables to determine the process sensitivities and their effect on the arc pressure, and to determine reduction methods. A novel concept of an arc interaction time, relating to gas conditioning, arc characteristics and the strength of the arc pressure, is proposed. A relationship between arc voltage and peak arc pressure is identified and proposed as a potential method of real-time pressure monitoring during WAAM operations. An empirical statistic process model was developed, which relates arc pressure to process conditions and torch design, allowing the selection of process variables while maintaining a minimum arc pressure in PTA WAAM, thus enabling higher currents and larger deposition rates while minimising keyhole defect risk. Arc pressure keyhole defect transition thresholds are identified for both stainless-steel and titanium. Arc pressure is determined as the predominant factor for initiating sharp keyhole defect transitions for a set of thermal conditions – a balance between thermal melt-pool fluid flow and arc pressure-induced hole size. A study of PTA electrodes was additionally undertaken to reduce arc pressure, improve arc starting, investigate wear and increase the longevity of electrodes and tip shape retention to optimise WAAM operations.PhD in Manufacturin
Reference class forecasting: promises, problems, and a research agenda moving forward
No full textReference Class Forecasting (RCF) has emerged as a prominent tool to counter chronic optimism in project planning. By applying an ‘outside view’ – using distributions of comparable past projects – RCF seeks to correct overly optimistic cost and schedule estimates that undermine megaproject delivery. While its adoption has expanded in policy and practice, particularly following Flyvbjerg’s work, questions remain about its validity, applicability and limitations. This article critically reviews the promises and problems of RCF and sets out a research agenda for moving the debate forward.Production Planning & Contro
Echo-Robot: Semi-autonomous cardiac ultrasound image acquisition using AI and robotics
No full textEchocardiography is a critical tool for diagnosing cardiovascular diseases, offering detailed insights into heart functions. However, its accessibility is currently limited by a shortage of trained sonographers, specific skill requirements, and the physical strain imposed on professionals during repetitive procedures. This article introduces a new robotic system designed to automate the acquisition of transthoracic echocardiography (TTE) images. The system autonomously adjusts the position and orientation of the ultrasound transducer based on analysing realtime ultrasound images, without relying on tomographic data or depth sensors. Initially, the transducer is manually placed on the subjects skin, and the system uses a deep learning approach to grade the quality of ultrasound images captured at each position. The robot then adjusts its position by spiralling outwards from the starting point, moving to the location with the highest image quality score. Next, the system fine-tunes the transducers orientation in 5-degree increments along all three axes of rotation, informed by another deep learning module to identify the field of view. The robotic system was tested using a cardiac simulator, achieving approximately 80 view when the probe was initially positioned randomly in a 6 by 6 cm area beneath the left nipple. The impact of this work would be rapid diagnostics in the Emergency Departments to reduce the length of stay in hospitals, a reduction of hospital admissions related to heart disease by accessing local healthcare communities, acceleration of clearing the post-Covid backlog, and improved quality of life and longevity of patients.IEEE Transactions on Medical Robotics and Bionic
Bridging the gap between the regulator and the regulated in safe emptying and transport of faecal sludge: approaches to support scaling service provision
No full textOver 1.5 billion urban residents globally rely on faecal sludge emptying and transport, often provided by a diverse private sector. Effective regulation is essential to ensure safe service delivery, correct market failures, and protect public health and the environment. Government involvement has grown, with local authorities often acting as regulators, translating national policies into action. Understanding how providers respond to regulation is key, particularly in informal, low-visibility services.
This thesis examines how to improve compliance with safe practices, focusing on eastern and southern Africa, where regulators and service authorities are scaling up sanitation services. Methods included key informant interviews, literature review, a Delphi study, and a validation workshop. A holistic compliance model was adapted to reflect findings, and a regulatory approach proposed.
Challenges include high compliance costs, low provider capacity, and weak enabling environments. Less-recognized barriers—such as societal disgust and lack of trust—also emerged. Moral courage from regulators and a shift toward building 'watchful trust' are essential. Including informal providers through mapping and capacity-based categorization is key. Compliance must be made understandable, easy, visible, and valued. A participatory, responsive approach and targeted public investment are critical for delivering safe services through a regulated private sector.Water & Sanitation for Urban Population