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Cui Y.,Nanyang Technological University | Shum P.P.,Nanyang Technological University | Hu D.J.J.,Agency for Science, Technology and Research Singapore | Wang G.,Chinese University of Hong Kong | And 3 more authors.
IEEE Photonics Journal | Year: 2012

In this paper, we report an optical fiber Sagnac interferometer (OFSI)-based temperature sensor constructed by a selectively filled polarization-maintaining photonic crystal fiber (PM-PCF). The transmission spectrum of the OFSI is in sinusoidal form and is sensitive to temperature. Simulation results predicted a higher sensitivity by selective filling than nonselective filling. In experiments, we used an extremely low-cost process to realize the selective filling. A sensitivity of 2.58 nm/\circC was achieved with an 11.7-cm-long PM-PCF. The sensitivity dependence on the infiltration length ratio was also investigated. © 2009-2012 IEEE.

Dinh X.-Q.,Nanyang Technological University | Dinh X.-Q.,Thales Solutions Asia Pte Ltd | Jiang M.,Nanyang Technological University | Shum P.P.,Nanyang Technological University | And 2 more authors.
2012 Photonics Global Conference, PGC 2012 | Year: 2012

We report an optical twisting alert sensor using beat frequency from a short cavity polarization-maintaining erbium-doped fiber (PM-EDF) based distributed Bragg reflector (DBR) laser. A DBR fiber laser with an effective cavity length of ∼ 1 cm formed by a pair of fiber Bragg gratings (FBGs) inscribed on a portion of PM-EDF was developed for demonstrated. This fiber laser exhibited stable operation in dual-polarization single-longitudinal-mode. The amplitude of the beat frequency generated by two orthogonal polarizations of the cavity is twist dependence. It is shown that the beat frequency signal can be completely 'turned off' at ∼ 180° twist angle. This type of single mode DBR fiber laser can be used as optical twisting alert sensors for remotely interrogated systems and multi-parameter monitoring systems. © 2012 IEEE.

Zhang H.,Nanyang Technological University | Wu Z.,Nanyang Technological University | Shum P.P.,Nanyang Technological University | Wang R.,Huazhong University of Science and Technology | And 5 more authors.
Journal of Optics (United Kingdom) | Year: 2016

We present the fabrication of fiber Bragg gratings (FBGs) in a trench-assisted heterogeneous multicore fiber (MCF). Two obviously different Bragg reflection peaks are obtained due to the slight difference of refractive indices between the center core and the outer cores. To investigate the reflections of the two FBGs simultaneously, only a segment of multimode fiber is inserted between the lead-in single mode fiber and the MCF. The experimental results confirm that the curvature sensitivity of the FBG in the outer core is a sinusoidal function of the bending orientation angle. The maximum linear curvature sensitivity is about 0.128 nm/m-1. The cross sensitivity to temperature or externally applied axial strain can be eliminated by discriminating the different responses of FBGs inscribed in outer cores and the center core. Thus this MCF with FBGs can be utilized as a directional bending sensor. Moreover, the proposed sensor offers several advantages, such as low cost and flexibility in fabrication. © 2016 IOP Publishing Ltd.

Bachatene H.,Thales Alenia | Landry S.,Thales Solutions ASIA PTE LTD | Toh K.-H.,Thales Solutions ASIA PTE LTD | Truong A.,Thales Solutions ASIA PTE LTD
Advances in Intelligent Systems and Computing | Year: 2016

This paper describes a method for product line system architecture applied to the Maritime Safety and Security domain. This approach aims to reconcile interests and concerns from various stakeholders in this domain: (i) End-user organisations and their operational needs, taking into account evolving economic, social and political constraints; (ii) Engineering teams, building product architectures, and managing product and solution development, and (iii) Sales and Marketing Teams, collecting and managing market needs and trends. Architecture and engineering data is exploited, using a customer-centric meta-model implemented to aid decision-makers from both business and technology perspectives, allowing them to understand and predict ROI of development of new system capabilities and to synchronize operational and technical roadmaps for affordable capabilities. © Springer International Publishing Switzerland 2016.

Kerr S.J.,Institute for Infocomm Research | Rice M.D.,Institute for Infocomm Research | Teo Y.,Institute for Infocomm Research | Wan M.,Institute for Infocomm Research | And 5 more authors.
Proceedings of VRCAI 2011: ACM SIGGRAPH Conference on Virtual-Reality Continuum and its Applications to Industry | Year: 2011

Augmented Reality (AR) technologies offer the potential to aid users in a number of professional areas. However, to date, most studies have been tested in controlled laboratory conditions. This paper outlines a user experience study of a wearable mobile augmented reality system in an outdoor urban environment. We describe the use case of using a see-through monocular headmounted display (HMD) with augmented imagery for orientation, and the use of gesture input for interacting with information while on-the-move. Participants had to navigate to a target location, whilst receiving information updates, and complete a series of gesture-based tasks. Despite participants managing to complete the tasks after some assistance, it was found that more improvements to the user experience are required for it to be viable in outdoor-use. In particular, better visibility, when seethrough HMDs are used in a bright environment, and improved situation awareness. This paper further highlights the difficulties in using gesture input, and points to a number of areas requiring further research into the use of wearable mobile AR systems in the context of this work. © 2011 ACM.

Lim H.S.,Thales Solutions Asia Pte Ltd | Rameshchandra K.,Thales Solutions Asia Pte Ltd | Toh W.S.,DSO National Laboratories
OCEANS 2011 IEEE - Spain | Year: 2011

Most beamforming algorithms for vector sensor array are derived based on the assumption that the directivity pattern of all sensors are perfectly aligned. However this is not true in practice and calibration for rotational perturbations are required to avoid drastic degradation of beamforming performance. This paper presents two algorithms that are capable of estimating and compensating rotational perturbation angles. The first algorithm is based on steering vector error and the second algorithm is based on subspace criteria. Computer simulations show that performance of both algorithms approach theoretical bound, are consistent and able to restore distorted spatial spectral in the presence of single and multiple sources. © 2011 IEEE.

Jamet P.,Thales Solutions Asia Pte Ltd | Jamet P.,CNRS IPAL UMI 2955 Joint Laboratory | Chew S.C.K.,Thales Solutions Asia Pte Ltd | Fagette A.,Thales Solutions Asia Pte Ltd | And 3 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2015

This paper deal with the flow tracking topic applied to dense crowds of pedestrians. Using the estimated density, a cloud of particles is spread on the image and propagated according to the optical flow. Each particles embedding physical properties similar to those of a pedestrian, this cloud of particles is considered as statistically representative of the crowd. Therefore, the behavior of the particles can be validated with respect to the behavior expected from pedestrians and potentially optimized if needed. Three applications are derived by analysis of the cloud behavior: the detection of the entry and exit areas of the crowd in the image, the detection of dynamic occlusions and the possibility to link entry areas with exit ones according to the flow of the pedestrians. The validation is performed on synthetic data and shows promising results. © Springer International Publishing Switzerland 2015.

Fagette A.,Thales Solutions Asia Pte Ltd | Courty N.,University of Southern Brittany | Racoceanu D.,University Pierre and Marie Curie | Dufour J.-Y.,Thales Alenia
Pattern Recognition Letters | Year: 2014

This study introduces a totally unsupervised method for the detection and location of dense crowds in images without context-awareness. With the perspective of setting up fully autonomous video-surveillance systems, automatic detection and location of crowds is a crucial step that is going to point which areas of the image have to be analyzed. After retrieving multiscale texture-related feature vectors from the image, a binary classification is conducted to determine which parts of the image belong to the crowd and which to the background. The algorithm presented can be operated on images without any prior knowledge of any kind and is totally unsupervised. © 2014 Elsevier B.V. All rights reserved.

Jiang M.,Nanyang Technological University | Dinh X.Q.,Nanyang Technological University | Dinh X.Q.,Thales Solutions Asia Pte. Ltd. | Shum P.P.,Nanyang Technological University | And 4 more authors.
IEEE Photonics Journal | Year: 2012

The effects of axial strain on beating frequency from a short cavity polarization-maintaining erbium-doped fiber (PM-EDF) based distributed Bragg reflector (DBR) laser were investigated theoretically and experimentally for the first time. This type of single-mode DBR fiber laser based ultrasensitive sensor has been extensively developed for measuring kinds of measurands, but the cross-sensitivity of axial strain was usually ignored. A DBR fiber laser with an effective cavity length of ∼1 cm formed by a pair of FBGs written on a PM-EDF was fabricated for demonstration. This laser operated in dual-polarization single-longitudinal mode stably. The frequency of the beating signal generated by two orthogonal polarizations was found to be proportional to the axial strain applied on the cavity. A linear strain sensitivity of 0.640 GHz/m was obtained, with a fiber birefringence of around 8.65e-5. For the fiber with larger birefringence, the sensitivity to the axial strain will be increased. So the effects of axial strain should be considered when the structure is utilized as a high-resolution sensor, especially for a polarization-maintaining system. The single-mode DBR laser made of high birefringent fibers also has a potential application in frequency tunable microwave generation. © 2012 IEEE.

Wu Z.,Nankai University | Wu Z.,Nanyang Technological University | Liu Y.-G.,Nankai University | Wang Z.,Nankai University | And 6 more authors.
Applied Physics Letters | Year: 2012

We report a compact in-line Mach-Zehnder interferometer combining a microtaper with a long-period grating (LPG) in a section of all-solid photonic bandgap fiber. Theoretical and experimental investigations reveal that the interferometer works from the interference between the fundamental core mode and the LP 01 cladding supermodes. The mechanism underlying the mode coupling caused by the microtaper can be attributed to a bandgap-shifting as the fiber diameter is abruptly scaled down. In addition, the interferometer designed to strengthen the coupling ratio of the long-period grating has a promising practical application in the simultaneous measurement of curvature and temperature. © 2012 American Institute of Physics.

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