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Dr Yang Liu


Date and Time: 13:00 - 14:00, Wednesday 19 January 2022

Venue: Zoom (Join Zoom Meeting)

Speaker: Mr Haohao Bi, CSC visiting PhD student, Department of Applied Mathematics, Northwestern Polytechnical University, Xi'an, China

Title: Static buckling behaviours and nonlinear dynamic analysis for a corrugated thin film on a pre-strained bi-layer substrate

Abstract: Bonding a thin stiff film on a pre-strained soft substrate to form a wavy configuration shape has been widely used to fabricate stretchable electronic devices. An intermediate layer between a thin stiff film and a substrate can enhance the adhesion of the film and modulate its buckling shape. Capturing buckling behaviours of the tri-layer film/intermediate layer/substrate structure and improving the robustness of this structure are essential for designing stretchable electronics. In this talk, an improved theoretical model of the buckled tri-layer structure is established. Then the governing equation of motion of this structure is derived, based on the geometrical homogenization theory. By using the Jacobi elliptic function, the analytical nonlinear frequency of the tri-layer structure with corrugated film is obtained. Finally, numerical examples are analysed to reveal the influences of the Young's modulus and thickness of the intermediate layer on the nonlinear frequency of the corrugated tri-layer structure. These results are helpful for the design of reliable film/substrate-type stretchable electronic devices.


Date and Time: 13:00 - 14:00, Wednesday 8 December 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Dr Ali K. Hoshiar, Assistant Professor, School of Computer Science and Electronic Engineering, University of Essex, UK

Title: Recent developments on microrobotic systems for swarm delivery of the therapeutics agents

Abstract: The rapid advancement in microrobotic systems in recent years for the medical applications, as well as human scale microrobotics systems, and advancements in the medical monitoring systems (magnetic particle imaging (MPI), fast MRI, and X-ray) lead to the precise control of microswarms in therapeutic delivery applications. However, predicting the nonlinear complex behaviour of the microswarms in the magnetic field remained as an open challenge. In this talk I will present the recent monitoring schemes (e.g., MPI), the practical actuation schemes, and most recent predictive models for microswarm control.


Date and Time: 13:30 - 14:30, Wednesday 3 November 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Professor Cunjia Liu, Reader in Unmanned Vehicles, Department of Aeronautical and Automotive Engineering, Loughborough University, UK

Title: Autonomous search of atmospheric CBR release using mobile robotics: From estimation to path planning

Abstract: In the event of unexpected release of Chemical, Biological and Radiological (CBR) substances into atmosphere, it is of critical importance to identify the source of the release and capture its possible dispersion. This talk will introduce a set of information theoretic approaches that can be used to guide a mobile robot platform to autonomously search the environment and characterise the source term of the airborne hazardous materials. An outline of the information theoretic framework for reconstructing the release term will be discussed, which will be followed by some case studies of deploying autonomous robotics to respond to chemical release incidents.


Date and Time: 12:30 - 13:30, Friday 10 September 2021

Venue: Harrison 170 or Zoom (Join Zoom Meeting)

Speaker: Prof. Pietro Valdastri, Professor and Chair in Robotics and Autonomous Systems, School of Electronic and Electrical Engineering, University of Leeds, Leeds, UK

Title: Medical capsule robots: a fantastic voyage

Abstract: At the beginning of the new millennia, wireless capsule endoscopy was introduced as a minimally invasive method of inspecting the digestive tract. The possibility of collecting images deep inside the human body just by swallowing a “pill” revolutionized the field of gastrointestinal endoscopy and sparked a brand-new field of research in robotics: medical capsule robots. These are self-contained robots that leverage extreme miniaturization to access and operate in environments that are out of reach for larger devices. In medicine, capsule robots can enter the human body through natural orifices or small incisions, and detect and cure life-threatening diseases in a non-invasive manner. This talk will provide a perspective on how this field has evolved in the last ten year. We will explore what was accomplished, what has failed, and what were the lessons learned. We will also discuss enabling technologies, intelligent control, possible levels of computer assistance, and highlight future challenges in this ongoing Fantastic Voyage.


Date and Time: 13:30 - 14:30, Friday 16 July 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Mr Jiyuan Tian, PhD candidate, College of Engineering, Mathematics and Physical Sciences, University of Exeter

Title: Exploring the dynamics of a vbro-impact capsule moving on the small intestine using finite element analysis

Abstract: This talk aims to study a realistic finite element (FE) model to depict the nonlinear dynamics of a vibro-impact capsule moving on the small intestine for active capsule endoscopy. The FE model takes both the nonlinear vibro-impact mechanism and the viscoelastic deformation of the small intestine into account. FE results are compared with the simulation results obtained using non-smooth differential equations and experimental results. It is found that the FE model can provide a more realistic prediction of the system in the complex intestinal environment in terms of capsule’s tilted motion and asymmetric distribution of capsule-intestine contact pressure. In particular, the capsule’s dynamics is very sensitive to the surface condition of the intestine, so a comprehensive bifurcation analysis is needed for fully understanding its dynamics under intestinal peristalsis.


Date and Time: 11:00 - 12:00, Monday 21 June 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Prof. Morteza Amjadi, Assistant Professor, Department of Mechanical Engineering, Heriot-Watt University, Edinburgh, Scotland, UK

Title: Functional nanomaterial composites for soft sensing and actuation

Abstract: Soft machines have many applications, ranging from multifunctional wearable medical devices for feedback therapy to prosthetics, non-invasive surgical tools, and soft robots for safe human-robot interaction. High-performance flexible sensors and actuators are the key components of soft machines. In this talk, I will cover our latest research activities on the development of functional nanocomposites based wearable sensors for human motion detection and soft robotics. I will demonstrate how bioinspired structures can help to improve the sensing and skin-adhesion performance of wearable sensors. The next part of my talk will focus on the development of programmable soft actuators based on composite materials. Finally, I will address challenges associated with the design of integrated soft machines capable of multimodal sensing and controlled stimulation.


Date and Time: 14:00 - 15:00, Monday 14 June 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Prof. Kevin Chen, Assistant Professor, Department of Electrical Engineering and Computer Science, MIT, USA

Title: Agile and robust micro-aerial-robots powered by soft artificial muscles

Abstract: Recent advances in microrobotics have demonstrated remarkable locomotive capabilities such as hovering flights, impulsive jumps, and fast running in insect-scale robots. However, most microrobots that are powered by power-dense rigid actuators have not achieved insect-like collision resilience. Meanwhile, the agility of most soft-actuated microrobots remains limited compared to that of rigid-actuated robots. In this talk, we will present our recent effort in developing a new class of microrobots – ones that are powered by high bandwidth soft actuators and equipped with rigid appendages for effective interactions with environments. Towards improving collision robustness of micro-aerial robots, we develop the first heavier-than-air aerial robots powered by soft artificial muscles that demonstrate open-loop, passively stable ascending flight as well as closed-loop, hovering flight. In addition, our robot can recover from an in-flight collision and perform a somersault within 0.16 seconds. This work demonstrates for the first time that soft aerial robots can achieve agile and robust flight capabilities absent in rigid-powered micro-aerial vehicles, thus showing the potential of a new class of hybrid soft-rigid robots.


Date and Time: 13:30 - 14:30, Friday 28 May 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Professor Przemys┼éaw Perlikowski, Faculty of Mechanical Engineering, Lodz University of Technology, Poland

Title: Application of a planetary variator in the tuned mass damper with variable inertance

Abstract: In this talk, we will analyze a planetary variator in terms of dynamical modelling and assessing its efficacy in a tuned mass damper with variable inerter (TMDVI). We will use the modified off-the-shelf planetary variator, and create kinematic and dynamic models of the device and experimentally determine its parameter values. Next, we theoretically consider implementing the device as a part of the TMDVI. The variator enables tuning of the natural frequency of the TMDVI to the current frequency of excitation. Hence, it allows crossing the resonance frequency via an optimal path with small oscillations amplitude of the main body. Additionally, we extend the previously proposed control method of the TMDVI to obtain efficient mitigation of vibrations in a wide range of excitation frequencies. The damped system's amplitude does not exceed 0.0084 [m], which is significantly smaller than the oscillation of the undamped system or system with optimized tuned mass damper.


Date and Time: 11:00 - 12:00, Friday 14 May 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Dr Zhihua Xie, Senior Lecturer, School of Engineering, Cardiff University, Cardiff, UK

Title: Numerical simulation of turbulent interfacial flows and fluid-structure interaction

Abstract: Interfacial flows over complex geometries with turbulent flow structures are often found in many hydraulic and coastal engineering applications. The objective of this study is to investigate the fluid dynamics of three-dimensional (3D) free surface flow problems, such as dam-break flow over structures, turbulent open-channel flow over rough beds, and wave-structure interaction. In this talk, a Cartesian cut-cell based multiphase flow code for solving 3D Navier-Stokes equations with interface capturing and large-eddy simulation approach is presented. Some numerical examples are shown to provide some insight into the flow physics and to demonstrate the capability of the numerical tool developed.


Date and Time: 13:30 - 14:30, Friday 30 April 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Dr Feng Zhou, University of Electronic Science and Technology of China, Chengdu, China

Title: Flow field analysis of the mechanical aortic bi-leaflet heart valves by using finite element method

Abstract: Under physiological conditions, the opening and closing of the leaflets of an implanted artificial heart valve (AHV) affect the blood components, and therefore, may cause various complications to the patients, such as hemolysis or platelet activation. In this talk, I will analyse the computational fluid model of AHV, which presents the regional distribution of flow shear stress, and evaluate the AHV performance by monitoring the variation of flow velocity and pressure when the blood passes the leaflets in the aortic valve. The obtained results suggest the design of a new mechanical artificial heart valve, including the increases of the maximum opening angle and internal orifice diameter, which can improve the fluid structure interaction and decrease the possibility of damage to blood components.


Date and Time: 15:00 - 16:00, Friday 23 April 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Miss Jiajia Zhang, PhD candidate, College of Engineering, Mathematics and Physical Sciences, University of Exeter

Title: Development of a vibro-impact self-propelled capsule in millimetre scale

Abstract: This talk will present the experimental study of a self-propelled capsule endoscope prototype (26 mm in length and 11 mm in diameter) driven by an external electromagnetic field. Mathematical models for both the external electromagnetic coils and the capsule prototype will be introduced. The strength of the magnetic field applied to the capsule was obtained analytically and verified by numerical simulations and experiments. The vibro-impact force exerted on the capsule will be compared with the analytical model and the experiment. By comparing capsule's trajectories under different control parameters, the advantage of using the vibro-impact self-propulsion technique can be revealed. Based on the experimental results, the optimised speed of the prototype can achieve up to 3.85 mm/s. Further ex vivo tests will also be presented to demonstrate the feasibility of the proposed technique for small-bowel endoscopy.


Date and Time: 11:00 - 12:00, Friday 16 April 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Dr Marcin Kapitaniak, School of Engineering, University of Aberdeen, UK

Title: Onset to Helical Buckling: FE modelling

Abstract: We develop a new Finite Element to accurately model twisting of rods and capture the bifurcation scenarios leading to helical buckling and various further post-buckling states. Since standard nonlinear beam elements do not account for nonlinearities in torsional modes, as well as for coupling between axial, lateral and torsional modes, we derive a new beam element, which allows us to describe complex helical buckling bifurcation scenarios of a rod subjected to a twisting load. The formulated beam element is systematically tested to assess its predictive capabilities in determining critical torsional buckling loads and its sensitivity to number of elements used. Once the model is validated against commercial FE software (Abaqus), we focus our attention on computing bifurcation scenarios to observe various complex helical configurations and transitions between them. The analysis reveals co-existence between helices with multiple loops for certain values of twisting load. Additionally, we trace the transition onsets between stable helical configurations. The developed FE can be applied to study complex buckling mechanics of engineering and biological structures.


Date and Time: 15:00 - 16:00, Friday 9 April 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Professor Benjamin S. Terry, Department of Mechanical and Materials Engineering, University of Nebraska Lincoln, Lincoln, US

Title: Oral delivery of biologics via swallowable mechanical capsules

Abstract: The preferred route of drug administration is oral, but large-molecule biological drugs (biologics), like vaccines and insulin, are delivered parenterally due to their intrinsic instability and low permeability through the physical, chemical, and immunological barriers of the gastrointestinal tract. Innovative swallowable technologies such as drug-loaded dissolvable microneedles, mucoadhesive patches, and various microdevices present unique biologic-carrying capabilities for oral delivery. Swallowable mechanical capsules have been used to diagnose and treat various gastrointestinal pathologies such as Crohn's disease, celiac disease, and small bowel tumors, and research to expand existing technology for drug delivery is still emerging. Our central objective is to orally deliver biologics, and we are accomplishing this via an ingestible mechanical capsule. Specifically, we are developing a capsule to deliver Adalimumab (an anti-inflammatory drug for the treatment of ulcerative colitis) into the submucosal layer of the small intestine. The capsule is designed to passively travel to the small intestine via digestive peristalsis after swallowing. Upon reaching the small intestine, the capsule attaches the drug-carrying payload onto the mucosa via a tissue attachment mechanism (TAM). The TAM is then separated from the capsule and remains adhered to the mucosa while the mechanical capsule exits the body in the typical manner. The primary subsystems of the device were individually validated on human-sized porcine models, and the fully integrated capsule was tested in vitro. The novel platform established in this work could be used for the oral delivery of a variety of biologics that are currently only delivered parenterally.


Date and Time: 13:30 - 14:30, Wednesday 31 March 2021

Venue: Zoom (Join Zoom Meeting)

Speaker: Miss Shuning Deng, CSC visiting PhD student, State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body, Hunan University, Changsha, China

Title: Dynamic analysis of a type of centrifugal governor system with time delay

Abstract: The centrifugal governor devices are commonly used in many rotating machines to prevent them from damages caused by a sudden change of the external load. Extensive works have been done on the modeling and dynamic analysis of the centrifugal governor systems, while much less effort has been made in investigating the time-delay effect. As a matter of fact, the inherent time-delay can widely exist in the centrifugal governor systems, due to many factors including the spring deformation, gear transmission, chemical combustion, and the steam transportation etc. In this talk, the local and global dynamics of the system with and without time delay will be studied in the two-parameter planes, including the stability analysis of equilibrium, the co-dimension one to co-dimension three bifurcations analyses of equilibrium, and the two-parameter dynamics identification. By comparing the dynamical response of the system with and without time delay, it was found that the time delay can have a great impact on the governor dynamics and the necessity of such system with time delay incorporated in the model was verified.


Date and Time: 13:30 - 14:15 am, Wednesday 6 November 2019

Venue: Peter Chalk 2.5

Speaker: Mr Yiwei Han, School of Mechatronic Engineering, Southwest Petroleum University, Chengdu, China

Title: Nonlinear dynamic modeling of drill string in horizontal well - a geometrically exact approach

Abstract: A new nonlinear dynamic model of drill string in horizontal well is established based on geometrically exact beam theory and quadrature element method. The model proposed in this work takes into account the geometric nonlinearity of the drill string and the nonlinear contact between the drill string and the borehole. Benefiting from the accuracy of the geometric description of the geometrically exact beam, the model uses a geometrically exact method to describe the contact between the drill string and the borehole. Comparison with experimental results shows that the geometrically exact model can accurately describe the nonlinear characteristics of the drill string. Finally, the characteristics of the movement of drill string under different drilling pressure and rotation speed will be analyzed. Drilling pressure and rotational speed have an effect on the buckling of the drill string. Before buckling, the drill string moves periodically at the bottom of the wellbore. After buckling, the movement of the drill string becomes disordered. The model presented in this work provides a new method for dynamic analysis of drill string.


Date and Time: 13:30 - 14:15 am, Friday 30 August 2019

Venue: Harrison 170

Speaker: Dr Moi Hoon Yap, Manchester Metropolitan University, Manchester, UK

Title: Translating Computer Vision Research to Real-World Applications

Abstract: The Human-Centred Computing Group undertakes research in computer vision, games, HCI and AI across the themes of healthcare, medical imaging and sport. In facial analysis, we create new algorithms for face wrinkles detection, micro-expressions detection/recognition, facial inpainting and denoising algorithms. We are working with external partners to deliver our research to real-world applications. This talk covers some of our recent works in facial analysis and medical image analysis. I will also share our journey of diabetic foot ulcer project, beginning from image processing to adoption of deep learning models, and to partnership with Oracle to create cloud-enabled prototype.


Date and Time: 11:00 - 12:00 am, Thursday 2 August 2018

Venue: Harrison 102

Speaker: Dr Yao Yan, School of Aeronautics and Astronautics, University of Electronic Science and Technology of China, Chengdu, China

Title: Unsafe cutting

Abstract: To analyse the multi-stability in the non-linear time-delayed metal cutting process, we employ a classical model of regenerative cutting and introduce the Stribeck effect and process damping to the tool’s rake and flank surfaces. From a practical point of view, the multi-stable regions are considered as unsafe due to its sensitivity to the initial conditions of cutting, which could lead the system to an undesired behaviour. So, it is vital to evaluate cutting safety through estimating its unsafe zones. For this purpose, we have attempted to define the basins of attraction and basin's stability by using this cutting model in order to get insight into the issues of cutting safety. Special attention will be paid to the influences of delayed initial conditions, starting points, and the states at time zero on the long-term dynamics of such a time-delayed cutting system. Finally, by using the analytical perturbation methods, our new model shows that the Stribeck effect affects the estimation of the unsafe zones excessively, so that only a very small part of the estimation is acceptable.


Date and Time: 11:00 - 12:00 am, Monday 30 July 2018

Venue: Harrison 102

Speaker: Professor Joseph Páez Chávez, Department of Mathematics, Faculty of Natural Sciences and Mathematics, Escuela Superior Politécnica del Litoral, Guayaquil, Ecuador

Title: A model for Dengue transmission dynamics with seasonal effects and impulsive control

Abstract: In this talk we will introduce an SIR epidemiological model describing the vector-to-host and host-to-vector transmission dynamics of Dengue. The proposed model includes vector control in terms of pesticide applications, mathematically described as impulsive perturbations in the system, thereby accounting for reductions of the vector population in very short time intervals. In addition, seasonality is incorporated into the model via a sinusoidal forcing mimicking periodic regimes of the intensity of vector-to-host and host-to-vector infections, as well as vector growth. A detailed numerical analysis of the model is carried out via path-following techniques for non-smooth systems, implemented via the software COCO. The numerical study also considers the optimization of the times at which pesticide is applied.


Date and Time: 10:30 - 11:30 am, Monday 18 December 2017

Venue: LSI Seminar Room A

Speaker: Dr Luigi Manfredi, Institute for Medical Science and Technology, School of Medicine, University of Dundee, Dundee, UK

Title: Design and Construction of a Mini Snake-Like Medical Robot

Abstract: This talk presents the design and construction of a novel mini snake-like robotic endoscope developed within the ERC Proof of Concept grant “Compliant Actuation Robotic Platform for Flexible Endoscopy” (CARPE), based on a novel and patented “Active Tether Concept” (ATC). In contrast with a traditional “push colonoscope”, the smart control provides an active locomotion reducing the force exchanged with the colonic wall, and therefore, the pain and discomfort in the procedure. The robotic frame is designed by finite element analysis to achieve a weight of only 0.7 grams for each joint, and a high force/torque to weight ration. ATC has an external diameter of 13 mm and a central hollow space of 5 mm, which can be used for essential services, such as suction/irrigation and biopsy channel. The head of the robot can carry a HD camera and the flexible active robotic endoscope will be controlled from an external console.