7,730 research outputs found
Physics and Applications of Laser Diode Chaos
An overview of chaos in laser diodes is provided which surveys experimental
achievements in the area and explains the theory behind the phenomenon. The
fundamental physics underpinning this behaviour and also the opportunities for
harnessing laser diode chaos for potential applications are discussed. The
availability and ease of operation of laser diodes, in a wide range of
configurations, make them a convenient test-bed for exploring basic aspects of
nonlinear and chaotic dynamics. It also makes them attractive for practical
tasks, such as chaos-based secure communications and random number generation.
Avenues for future research and development of chaotic laser diodes are also
identified.Comment: Published in Nature Photonic
Chaos-based underwater communication with arbitrary transducers and bandwidth
Acknowledgments: This research is supported in part by National Natural Science Foundation of China (61172070), Innovative Research Team of Shaanxi Province (2013KCT-04), The Key Basic Research Fund of Shaanxi Province (2016ZDJC-01), EPSRC (EP/I032606/1), Chao Bai was supported by Excellent Ph.D. research fund (310-252071603) at XAUT.Peer reviewedPublisher PD
Chaos for communication
Open access via Springer agreementPeer reviewedPublisher PD
Experimental Wireless Communication Using Chaotic Baseband Waveform
This work was supported by NSFC under Grants 61401354, 61172070, and 61502385, in part by the Key Basic Research Fund of Shaanxi Province under Grant 2016ZDJC0067, in part by the Natural Science Basic Research Plan in Shaanxi Province of China under Grant 2016JQ6015, in part by the Scientific and Technological Innovation Leading Talents Program of Shaanxi Province, and in part by the Foundation of Shaanxi Educational Committee under Grant 17JS086.Peer reviewedPostprin
Dynamic block encryption with self-authenticating key exchange
One of the greatest challenges facing cryptographers is the mechanism used
for key exchange. When secret data is transmitted, the chances are that there
may be an attacker who will try to intercept and decrypt the message. Having
done so, he/she might just gain advantage over the information obtained, or
attempt to tamper with the message, and thus, misguiding the recipient.
Both cases are equally fatal and may cause great harm as a consequence.
In cryptography, there are two commonly used methods of exchanging secret
keys between parties. In the first method, symmetric cryptography, the key is
sent in advance, over some secure channel, which only the intended recipient
can read. The second method of key sharing is by using a public key exchange
method, where each party has a private and public key, a public key is shared
and a private key is kept locally. In both cases, keys are exchanged between
two parties.
In this thesis, we propose a method whereby the risk of exchanging keys
is minimised. The key is embedded in the encrypted text using a process
that we call `chirp coding', and recovered by the recipient using a process
that is based on correlation. The `chirp coding parameters' are exchanged
between users by employing a USB flash memory retained by each user. If the
keys are compromised they are still not usable because an attacker can only
have access to part of the key. Alternatively, the software can be configured
to operate in a one time parameter mode, in this mode, the parameters
are agreed upon in advance. There is no parameter exchange during file
transmission, except, of course, the key embedded in ciphertext.
The thesis also introduces a method of encryption which utilises dynamic blocks, where the block size is different for each block. Prime numbers are
used to drive two random number generators: a Linear Congruential Generator
(LCG) which takes in the seed and initialises the system and a Blum-Blum
Shum (BBS) generator which is used to generate random streams to encrypt
messages, images or video clips for example. In each case, the key created is
text dependent and therefore will change as each message is sent.
The scheme presented in this research is composed of five basic modules. The
first module is the key generation module, where the key to be generated is
message dependent. The second module, encryption module, performs data
encryption. The third module, key exchange module, embeds the key into
the encrypted text. Once this is done, the message is transmitted and the
recipient uses the key extraction module to retrieve the key and finally the
decryption module is executed to decrypt the message and authenticate it.
In addition, the message may be compressed before encryption and decompressed
by the recipient after decryption using standard compression tools
Synchronization of Chaotic Optoelectronic Oscillators: Adaptive Techniques and the Design of Optimal Networks
Synchronization in networks of chaotic systems is an interesting phenomenon with potential applications to sensing, parameter estimation and communications. Synchronization of chaos, in addition to being influenced by the dynamical nature of the constituent network units, is critically dependent upon the maintenance of a proper coupling between the systems. In practical situations, however, synchronization in chaotic networks is negatively affected by perturbations in the coupling channels. Here, using a fiber-optic network of chaotic optoelectronic oscillators, we experimentally demonstrate an adaptive algorithm that maintains global network synchrony even when the coupling strengths are unknown and time-varying. Our adaptive algorithm operates by generating real-time estimates of the coupling perturbations which are subsequently used to suitably adjust internal node parameters in order to compensate for external disturbances. In our work, we also examine the influence of network configuration on synchronization. Through measurements of the convergence rate to synchronization in networks of optoelectronic systems, we show that having more network links does not necessarily imply faster or better synchronization as is generally thought. We find that the convergence rate is maximized for certain network configurations, called optimal networks, which are identified based on the eigenvalues of the coupling matrix. Further, based on an analysis of the eigenvectors of the coupling matrix, we introduce a classification system that categorizes networks according to their sensitivity to coupling perturbations as sensitive and nonsensitive configurations. Though our experiments are performed on networks consisting of specific nonlinear optoelectronic oscillators, the theoretical basis of our studies is general and consequently many of our results are applicable to networks of arbitrary dynamical oscillators
Double-Stream Differential Chaos Shift Keying Communications Exploiting Chaotic Shape Forming Filter and Sequence Mapping
ACKNOWLEDGMENT This research have been supported in part by the Scientific and Technological Innovation Leading Talents Program of Shaanxi Province, China Postdoctoral Science Foundation Funded Project (2020M673349), Open Research Fund from Shaanxi Key Laboratory of Complex System Control and Intelligent Information Processing (2020CP02)Peer reviewedPostprin
EPSRC IMPACT Exhibition
This exhibition was conceived by Dunne (PI) and comprised 16 mixed-media speculative design research projects. It marked the culmination of an EPSRC-funded initiative also partly supported by NESTA. Dunne supervised and then curated the projects by staff, graduates and students of the RCA Design Interactions programme. Each was conducted in collaboration with an external research partner organisation already supported by the EPSRC.
The topics covered ranged from renewable energy devices and security technologies to the emerging fields of synthetic biology and quantum computing. Dunne and an advisory panel from EPSRC and NESTA selected themes on the basis of diversity of topic, design opportunities, intellectual and creative challenges, and public relevance. Dunne invited the designers to take a radical, interrogative approach, exploring the social, ethical and political implications of the research. Each designer visited the relevant science lab, consulted with the scientists throughout the project, and participated in a one-day workshop hosted by NESTA between scientists and designers on such forms of collaboration. Designers carried out literature, journal, and project surveys before developing their projects through iterative prototypes.
The exhibition, held at the RCA in 2010, was considered by EPSRC to offer a powerful insight into how today’s research might transform our experience of the world. It was reviewed in the Guardian (2010), Wired (2010) and Design Week (2010).
Dunne presented ‘IMPACT!’ in conferences including the IDA Congress, ‘Design at the Edges’, Taipei (2011) and at the Wellcome Trust, London (2011). He gave a related lecture to researchers at Microsoft Research Asia, Beijing (2011). Individual exhibits from the project featured in exhibitions: Museum of Modern Art (2011), National Museum of China (2011); Z33 (2010–11); Wellcome Trust (2010–11); Saint-Étienne International Design Biennial (2010); Ars Electronica (2010); The Times Cheltenham Science Festival (2010); and V2_, Institute for the Unstable Media (2010)
- …