1,721,077 research outputs found
Nile red-dye based analysis of synthetic fibres for forensic applications.
Full text linkForensic evaluation of crime scenes normally involves examination of textile fibers, to find out the association between an individual and a crime scene, or between a suspect and a victim. The forensic samples normally include a mix of various types, sizes (micro to nano - scale) and shapes of natural and synthetic fibers, which are very difficult to differentiate/identify. Various sophisticated analytical instruments are being used to carry out the examination of these fibers. They involve various microscopy and spectroscopy based techniques, most of which are very complex and highly sensitive. Further, they may require a series of sample preparation steps to get high selectivity and are highly time consuming. Here we report a fluorescence microscopy based synthetic (plastic) fiber detection method using Nile Red (NR) dye, which provides high selectivity for synthetic fibers. The methodology involves the use of NR dye which selectively stains the fibers collected on filter papers following separation from samples/soils and water. The selectivity of NR towards the fibers is due to their non-polar property. Binding with NR makes the fibers fluoresce when viewed under a fluorescence microscope. This selectivity of NR for fibers makes the identification of fibers lot easier and less timeconsuming in forensic samples when compared to the more commonly used optical microscopy (where the presence of naturally-occurring substances of similar size can result in more errors). The paper will discuss optimisation of various parameters and method validation for detection of synthetic fibers and microplastics from soil samples. As an example, our method has shown to provide distinct clarity for the analysis of microfibers. The potential for the application of the method for faster forensics analysis will be discussed
Investigations of hollow-core photonic crystal fibres (HC-PCF) for trace explosive vapour detection.
Get PDFTrace detection and identification of hazardous volatile explosives has been a key challenge to the scientific community past many decades. Commercially available various analytical and spectroscopic techniques suffer from low sensitivity, swabbing of surfaces and low detection limit. Triacetone Triperoxide (TATP), used in improvised explosive devices IEDs vaporizes readily at room temperature and has a vapour signature. However, explosive trace detectors (ETDs) are incompetent to detect TATP due to absence of chromophoric groups. We have investigated the novel hollow core photonic crystal fibres (HC-PCFs) based Raman sensor for real time monitoring of such volatile explosives in airport security. Raman scattering, a powerful, non-destructive tool provides molecular fingerprinting and is a potential candidate for detection of trace explosives but suffer from weak signal strength. Simultaneous confinement of pumped light and gas in HCFs allows greater light gas interaction providing an excellent optical sensing platform. These sensors can be easily incorporated at the security terminals or baggage counters with the existing metal detection systems. This paper reports investigations carried out on the HC-PCF designed using COMSOL Multiphysics software. The Raman signal being dependent on its intensity and mode area, simulations were conducted to analyse PCF parameters like confinement losses and mode field diameter/ effective mode area and its associated wavelength dependency. Theoretical study carried out on the HC-PCF also revealed that mode field confinements within the hollow core can be modified to suit specific laser wavelengths and confinement losses can be reduced to achieve Raman signal enhancement by optimizing their geometrical parameters like air-hole size and pitch/ hole-to-hole distance
A simulation into the physical and network layers of optical communication network for the subsea video surveillance of illicit activity.
Full text linkCriminal activity is increasingly entering the ocean subsurface with acts such as illegal fishing and narco-submarining becoming points of contention. This among other illicit acts taking place in this domain imply a need for surveillance to render these activities apparent. However, subsurface Underwater Sensor Networking which is central to the surveillance is still generations behind terrestrial networking, therefore it is still challenging to monitor for subsurface activities. This is since the current signal transmission standard, acoustic communication, is limited in practical bandwidth and thus channel data-rate, this is, however, caveated with omni-directional propagation and supreme range rendering it reliable but incapable of carrying video or other data intensive sensor information. There is, however, an emerging technology based on optical (visible light) communication that can accommodate surveillance applications with superior data rates and energy savings. This investigation demonstrates how theoretically it is possible to achieve a network of underwater channels capable of sustaining a multimedia feed for monitoring subsurface activity using modern optical communication when in compared to an acoustic network. In addition, a simple topology was investigated that shows how the range limitations of this signaling can be extended by adding floating relay nodes. Through simulations in Network Simulator 3 (NS-3)/Aquasim-NG software it is shown that Visible Light wireless communication in visible light networks have a channel capacity high enough to carry out monitoring in strategic areas, referencing, optical modems that are available in the market. This implies that data-rates of 10 Mb/s are possible for the real-time video surveillance
Waveguide-based machine readable fluorescence security feature for border control and security applications.
Full text linkBorder security challenges and immigration issues are increasing considerably in recent years. Counterfeiting and fraudulent use of identity and other travel documents are posing serious threats and safety concerns worldwide, ever since the advancement of computers, photocopiers, printers and scanners. Considering the current scenario of illegal migration and terrorism across the world, advanced technologies and improved security features are essential to enhance border security and to enable smooth transits. In this paper, we present a novel dual waveguide based invisible fluorescence security feature and a simple validation system to elevate and strengthen the security at border controls. The validation system consists of an LED (light emitting diode) as excitation source and an array photodetector which helps in the simultaneous detection of multiple features from the fluorescence waveguides. The fluorescence waveguides can be embedded into the identity document as micro-threads or tags which are invisible to the naked eye and are only machine readable. In order to improve the sensitivity, rare earth fluorescence materials are used which absorb only specific ultraviolet (UV) or visible (VIS) wavelengths to create corresponding fluorescent emission lines in the visible or infrared wavelengths. Herein, we present the preliminary results based on the fluorescence spectroscopic studies carried out on the fabricated rare earth doped waveguides. The effect of different rare earth concentrations and excitation wavelengths on the fluorescence intensity were investigated
Fluorescence lifetime assisted enhanced security feature in travel documents for border control and security applications.
Full text linkBorder management and security challenges are increasing considerably in recent years. One of the major concerns is counterfeiting and fraudulent use of identity and other travel documents for crossing border controls. This poses serious threats and safety concerns worldwide, considering the scenario of terrorism and illegal migration across the world. Hence, advanced technologies with improved security features becomes essential to strengthen border security and to enable smooth transits. In this paper, we present a novel dual waveguide based invisible fluorescence security feature with lifetime discrimination and a simple validation system. Molecular fluorescence and lifetimes from the rare earth doped waveguides can be used as additional security features in the identity documents. The validation system consists of a modulated excitation source and fast photo-diodes which helps in the simultaneous detection of multiple security features from the fluorescence waveguides. The rare earth doped fluorescence waveguides are embedded into the identity document as micro-threads or tags which are invisible to the naked eye and are only machine readable. Rare earth fluorescence materials have higher sensitivity and selectivity as they absorb only specific ultraviolet (UV) or visible (VIS) wavelengths to create corresponding fluorescent emissions in the visible or infrared wavelengths. Herein, we present the results based on the fluorescence and fluorescence lifetime spectroscopic studies carried out on the terbium (Tb) and dysprosium (Dy) doped waveguides. The different emission wavelengths and lifetimes of these rare earth elements is a key differentiating feature, providing selectivity and security to the detector systems
Adaptive path-planning for AUVs in dynamic underwater environments using sonar data.
Full text linkThis paper presents an innovative approach to path-planning for Autonomous Underwater Vehicles (AUVs) in complex underwater environments, leveraging single-beam sonar data. Recognizing the limitations of traditional sonar systems in providing detailed environmental data, we introduce a method to effectively utilize Ping360 sonar scans for obstacle detection and avoidance. Our research addresses the challenges posed by dynamic underwater currents and obstacle unpredictability, incorporating environmental factors such as water temperature, depth, and salinity to adapt the sonar’s range detection capabilities. We propose a novel algorithm that extends beyond the capabilities of the A* algorithm, considering the underwater currents’ impact on AUV navigation. Our method demonstrates significant improvements in navigational efficiency and safety, offering a robust solution for AUVs operating in uncertain and changing underwater conditions. The paper outlines our experimental setup, algorithmic innovations, and the results of comprehensive simulations conducted in a controlled tank environment, showcasing the potential of our approach in enhancing AUV operational capabilities for defense and security applications
Feasibility analysis of unique ID (UID) generation for personal authentication of valuable documents using dorsal hand vein pattern.
Full text linkReliable personal authentication is a critical and vital obligation to the security in all the real-world applications. Nevertheless, biometric features are effectively used for the personal authentication, in some cases the criminal impersonation is an easy task. The reproducible attack in fingerprint system and cost prohibitive nature of iris and facial based system limit the vast implementation of the same for personal authentication. Hence, considering the cases of increasing identity theft, there is more reason than ever to ensure the reliable and cost-effective personal authentication. The vein biometric identification system has been gaining increased attention in recent years. Anatomically, the shape of the vein pattern at the dorsal hand is unique for each even for identical twins and remains stable for a period. The objective of this work is to conduct a feasibility analysis of unique ID generation using dorsal hand vein pattern as the biometric authentication system for preventing identity theft of the valuable documents. Images of the vein pattern from the dorsal side of the hand are tried to capture using a regular type Smartphone camera. Vein pattern thus captured is used to extract the unique features. Numerical values generated from such unique feature are encrypted and used to create a unique ID. This paper discusses about the method for the dorsal hand vein pattern capturing, its feature extraction, conversion to the unique ID and its feasibility to integrate to the valuable documents
Speckle pattern analysis of security holograms and related foils for quality assessment and authentication.
Full text linkA speckle pattern is produced by the mutual interference of a set of coherent wavefronts. Speckle patterns typically occur in diffuse reflections of monochromatic light such a laser light. When a rough surface is illuminated by a coherent light is imaged, a speckle pattern is observed in the image plane. This study involves the quality assessment and authentication of security holograms and its related foils by analyzing the speckle pattern generated from the specimen itself. Speckle pattern from various type of security holograms and foils are taken. By processing the image of the speckle pattern, the size of the speckles is analyzed using MATLAB software. By evaluating the size of the speckle generated, the feasibility of analyzing the quality and authenticity of the security hologram is assessed. The paper discusses about the experimental setup, image capturing, and processing method and the result obtained in detail
Fuzzy logic, edge enabled underwater video surveillance through partially wireless optical communication.
Full text linkUnderwater surveillance is inherently tricky to achieve. Even in the clearest waters, the visibility tends to be in the range of tens of meters. Normally, tethered Remotely Operated Vehicles (ROVs) with underwater cameras are used for underwater imaging at closer ranges. Currently, detailed visible light imaging can be achieved utilising green laser technology, and this is limited to close ranges due to the inherent properties of light attenuation in water. The alternative is to utilise sonar based imaging which is capable of visualising distances, however, this technique is vulnerable to noise that interferes with the operating frequency, rendering the applications somewhat limited. The emergence of high data-rate, wireless, optical communication could allow for dense placement of short-range imaging equipment to monitor areas of strategic interest to extend the range, however, there needs to be a reliable method of wirelessly communicating this data to the sea surface regardless of the localised environmental conditions that may interfere with a visible light transmission. This paper proposes a fuzzy logic, edge computing enabled routing algorithm for optical networks that utilises a wired connection among source nodes to "pass" video data around among themselves to decide which seafloor node is best placed to transmit the data according to relative local turbidity, light intensity and sea-life activity, the main factors that hamper a well-considered wireless optical network. From there, a selected node can theoretically transmit the data from the source to the sea-surface through the wireless optical relay network implemented above. This mechanism shows promise in improving link reliability and throughput compared to alternative systems
AI-enhanced imaging and multimodal detection of rare-earth fluorescence-based security features for document authentication and border control.
No full textAdvanced document forgeries using color-matched inks and counterfeit ultraviolet pigments pose significant challenges for border security, evading conventional optical scanners. This study introduces an AI-enhanced imaging framework for authenticating documents via rare-earth-based fluorescence security features, such as invisible waveguides, which are robust against replication. Our approach leverages deep learning to eliminate the need for specialized optics, enabling reliable detection with standard cameras. We developed a dataset of co-registered white-light and fluorescence image pairs, trained a Conditional Generative Adversarial Network (CGAN) to generate synthetic fluorescence from white-light inputs, and implemented a YOLO-v8-based detector for real-time identification of embedded security features. This pipeline achieves a signal-to-noise ratio gain of +8.5 dB and 97% detection accuracy, offering a scalable, cost-effective solution for border checkpoints. By integrating the physical resilience of rare-earth luminescence with AI adaptability, our framework enhances document authentication, strengthens anti-counterfeiting measures, and facilitates efficient passenger processing
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