548 research outputs found
Formation control and collision avoidance for a class of multi-agent systems
No full textAbstract Not AvailableYutong Liu, Hongjun Yu, Peng Shi, Cheng-Chew Li
From Simulation to Bedside: the Missing Link in Pediatric Training Research [Response to Letter]
No full textHongjun Ba, Lingling Xu, Huimin Peng, Yufen Gu, Yijuan Li, Xiaoyun Jiang, Xiaoyu Li, Shujuan Li Pediatric Department, The First Affiliated Hospital of Sun Yat-Sen University, Guangzhou, 510080, People’s Republic of ChinaCorrespondence: Xiaoyu Li, Email [email protected] Shujuan Li, Email [email protected]
Steady formation analysis on multi-robot systems
No full textIn this paper, a controller is designed for a group of cooperative robots to achieve the stable displacements. Communication network among the robots is assumed unavailable and each robot can only measure the displacements relative to their neighbours. The controller will enable the robots to move to a predefined formation or a special formation under a suitable protocol which we will design. We will discuss the effect of different sizes of the multi-vehicle system and conduct simulations to verify the effectiveness of the proposed controller and the formation protocols.Yutong Liu, Hongjun Yu, Cheng-Chew Lim and Peng Sh
Scale-Heights Of Galactic Disks And Their Correlation With The Colour Index Of The Galaxies
No full textINTRODUCTION The scale-height of galactic disk (SGD) is certainly an important parameter for understanding spiral galaxies. While the SGD of edge-on galaxies may been determined through the van der Kruit's method (1981) (with a locally isothermal model and based on their surface photometry), SGD of the non edge-on spiral galaxies (which are the most of spiral galaxies) may be determined by observing the spiral pattern (Peng 1988). Based on Peng's method with good quality images of galaxies through CCD image observasion ( using the 1-m telescope at Yunnan Observatory), the scalehights of seven face-on spiral galaxies have been obtained ( Shang et al. 1992). Using the Atlas of Galaxies (Sandage & Bedke,1988) and based the Peng's method, the scalehights of 35 spiral galaxies also obtained and a statistical correlation between the colour indices and the scalehights of disk galaxies has been found in the present work. II. PRINCIPLE OF DETERMINING SCALEHEIGHT OF NON EDGE-O
Event-triggered probability-driven adaptive formation control for multiple elliptical agents
No full textIn this article, an event-triggered control scheme is proposed for a group of elliptical agents to achieve a predefined formation. The agents are assumed to have the same dynamics, and the control law for each agent is only updated at its event sequence based on its own minimum collision time and deviation time. The probability-driven controller is designed to prevent the stuck problem among agents. Mapping-adaptive strategy and angle-adaptive scheme based on the minimum collision distance are also developed. Two examples are presented to analyze and demonstrate the effectiveness and potential of the new eventtriggered adaptive control algorithm.Yutong Liu, Peng Shi, Hongjun Yu, and Cheng-Chew Li
Rotated Half-Mode Substrate Integrated Waveguide and other Planar Integrated Structures
No full textHigh data rate communication channels are becoming more and more integrated into our increasingly technological society. Substrate Integrated Waveguides (SIW) are one planar solution available to the microwave engineer, offering a low-loss and low dispersion means of propagating these high speed, high bandwidth signals.
In this thesis, a brief synopsis of SIW structures and components is presented covering the basic waveguide propagating modes and cut-off frequencies. The main analysis techniques associated with SIWs including full wave electromagnetic modelling methods are overviewed, and the associated loss mechanisms of conduction, dielectric and radiation defined, leading to the design rules and guidelines on how best to mitigate them.
SIW antennas as both leaky-wave and radiating slots are discussed and an example of a single and dual resonating slot antenna design is presented, along with a detailed review of a novel switch beam antenna developed for use within the current WiFi bands.
The Slot SIW (or SSIW), which has a small longitudinal gap in one of the main conducting surfaces, allows easy integration of lumped elements or active devices, enabling the waveguide to be loaded with impedances or to be shorted. When the slot is shorted, the waveguide reverts back to the full SIW mode, and when partially loaded an intermediate state results. This is discussed, and the SSIW analysed with the transverse resonance technique, leading to the development of a travelling wave attenuator with the SSIW being periodically loaded with pin diodes. The application of the pin diodes required the use of a capacitive overlay, a development of flexi circuit design to allow capacitive coupling of impedances to connect to the waveguide. The overlay concept is extended further, to form novel passive bandpass filters, with the introduction of virtual vias.
A limitation of the SSIW is that the majority of the field resides within the dielectric; this allows only a limited interaction with the field at the slot. The rotated Half Mode SIW (rHMSIW), a new variant of the SIW family, places the maximum of the electric field directly on the top dielectric surface, allowing for direct interaction. The waveguide width a is now defined by the dielectric thickness, allowing for the waveguide height b to be adjustable, in normal SIWs this is the other way round; the dielectric thickness fixing the waveguide height and the waveguide width being adjustable. The rHMSIW is characterised with regard to the height and width ratios b/a and the dielectric exposed width (which is adjustable). These parameters effect the modal cut-off frequency, this is investigated and a new equation describing the fundamental mode cut-off frequency is empirically derived. Finally a test coupon which spans the Ku band is designed and measured, which required the development of a novel waveguide transition
Exploring the brain epitranscriptome: perspectives from the NSAS summit
No full textIncreasing evidence reinforces the essential function of RNA modifications in development and diseases, especially in the nervous system. RNA modifications impact various processes in the brain, including neurodevelopment, neurogenesis, neuroplasticity, learning and memory, neural regeneration, neurodegeneration, and brain tumorigenesis, leading to the emergence of a new field termed neuroepitranscriptomics. Deficiency in machineries modulating RNA modifications has been implicated in a range of brain disorders from microcephaly, intellectual disability, seizures, and psychiatric disorders to brain cancers such as glioblastoma. The inaugural NSAS Challenge Workshop on Brain Epitranscriptomics hosted in Crans-Montana, Switzerland in 2023 assembled a group of experts from the field, to discuss the current state of the field and provide novel translational perspectives. A summary of the discussions at the workshop is presented here to simulate broader engagement from the general neuroscience field
Replication Data for: 'Investor Memory and Biased Beliefs: Evidence from the Field'
No full textThe programs replicate tables and figures from "Investor Memory and Biased Beliefs: Evidence from the Field," by Jiang, Liu, Peng, and Yan. (2025-07-22
Formation Control of Localised and Decentralised Robotic Swarms
No full textRobot swarms consist of multiple autonomous robots, which detect and interact with their local environments. The fundamental intelligence is observed when a chaotic swarm reaches a stable and orderly objective formation. The process is important because the objective formation is designed such that the swarm achieves more than the sum of its individuals. A formation is a set of positions or tasks, and intelligent swarms are capable of self-organising and task allocating. Given an objective formation, individuals of a swarm reach different objective positions and perform different tasks. This implies task allocation in different possible choices. For each individual, the path to its objective position is regarded as the efort to take, and the inclination to different objective tasks means different eforts. The challenge is that it needs to choose wisely in the interaction with its neighbourhood. Changes of choices are compromises and each progress to the objective position imposes in uence on its neighbourhood. The collective intelligence comes from series of individual decisions in the process. In this thesis, we consider four problems that arise with the challenge. We use techniques from graph theory and agent-based design to address them. Formation control algorithms should not impose heavy burden in the communication network. Thus, to start with, limited sensing and communication are assumed, and the robots have minimal access to each other's identity through locally established channels. The control strategy is proposed based on local optimisation and multi-object mapping for a team of robots. Robots are able to make mapping decisions based on local information. To achieve the local optimal mapping decisions for each robot, two novel multi-object mapping protocols are designed. The first protocol performs confict locating and resolving, and the second adopts a most-neighbour mapping strategy. The formation problem is further addressed for a scalable team of robots subject to limited sensing with no communication. The robots themselves are fully independent with no designated roles. Scalable objective formation design is proposed such that the robot formation is scalable. Under the assumption that the data transmission among the robots is not available, a novel controller and a protocol are designed that do not rely on communication. As the controller only drives the robots to a partially desired formation, a distributed coordination protocol is proposed to resolve the imperfections. The case is investigated where the objective formations are arbitrary and have fixed sizes. Multi-objective mapping is proposed for the individual robots to identify their positions in the objective formation. The fixed formation size induces mapping loops, and to avoid local optimum traps, an evaluation method imposes a weak restriction on the predened formation, rendering it almost arbitrary. To enhance the robustness, the minimal local topology is proposed, and to reduce the computation burden and avoid the infnite trajectory loop, the coordination protocol is modifed by introducing probability. The practical problem of collision avoidance is also studied. The leaderfollower scheme is implemented on a multi-robot platform. On the premise of coordinated control laws, globally desired formation is achieved. The same problem in the path-planning perspective is considered on a global scale. Disc obstacles are filtered and clusters are identified based on their intersections. The path planning algorithm is designed based on obstacle clusters.Thesis (Ph.D.) -- University of Adelaide, School of Electrical & Electronic Engineering, 201
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