Instantaneous Detection Research Articles

Instant detection and identification of concealed explosive-related compounds: Induced Stokes Raman versus infrared

The instant detection of explosives and explosive-related compounds has become an urgent priority in recent years for homeland security and counter-terrorism applications. Modern techniques should offer enhancement in selectivity, sensitivity, and standoff distances. Miniaturisation, portability, and field-ruggedisation are crucial requirements. This study reports on instant and standoff identification of concealed explosive-related compounds using customized Raman technique. Stokes Raman spectra of common explosive-related compounds were generated and spectrally resolved to create characteristic finger print spectra. The scattered Raman emissions over the band 400:2000cm−1 were compared to infrared absorption using FTIR. It has been demonstrated that the two vibrational spectroscopic techniques were opposite and completing each other. Molecular vibrations with strong absorption in infrared (those involve strong change in dipole moments) induced weak signals in Raman and vice versa. The tailored Raman offered instant detection, high sensitivity, and standoff detection capabilities. Raman demonstrated characteristic fingerprint spectra with stable baseline and sharp intense peaks. Complete correlations of absorption/scattered signals to certain molecular vibrations were conducted to generate an entire spectroscopic profile of explosive-related compounds. This manuscript shades the light on Raman as one of the prevailing technologies for instantaneous detection of explosive-related compounds.

VELOCITY VARIATIONS IN THE PHOENIX–HERMUS STAR STREAM

ABSTRACT Measurements of velocity and density perturbations along stellar streams in the Milky Way provide a time-integrated measure of dark matter substructure at larger galactic radius than the complementary instantaneous inner-halo strong lensing detection of dark matter sub-halos in distant galaxies. An interesting case to consider is the proposed Phoenix–Hermus star stream, which is long, thin, and on a nearly circular orbit, making it a particular good target to study for velocity variations along its length. In the presence of dark matter sub-halos, the stream velocities are significantly perturbed in a manner that is readily understood with the impulse approximation. A set of simulations shows that only sub-halos above a few 107 M ⊙ lead to reasonably long-lived observationally detectable velocity variations of amplitude of order 1 km s−1, with an average of about one visible hit per (two-armed) stream over a 3 Gyr interval. An implication is that globular clusters themselves will not have a visible impact on the stream. Radial velocities have the benefit of being completely insensitive to distance errors. Distance errors scatter individual star velocities perpendicular and tangential to the mean orbit, but their mean values remain unbiased. Calculations like these help build the quantitative case to acquire large, fairly deep, precision velocity samples of stream stars.

Instantaneous detection of melamine by interference biosynthesis of silver nanoparticles

Instantaneous detection of melamine, a potential milk adulterant has been demonstrated at room temperature by means of interference biosynthesis of silver nanoparticles. The sensing mechanism is based on the colorimetric change observed during the synthesis of silver nanoparticles due to the presence of melamine added during the biosynthesis. Presence and absence of melamine led to either inhibition of nanoparticle formation or enable partial synthesis of nanoparticles which is detected spectrally. A limit of detection (LOD) of 0.1ppm in water and 0.5ppm in raw milk was detected by the proposed technique at room temperature. UV–vis spectroscopy and High Resolution Transmission Electron Microscopy (HR-TEM) have been used to detect the spectral Surface Plasmon Resonance (SPR) and morphological changes of synthesized silver nanoparticle with and without the presence of the analyte melamine. Further, interference synthesis based sensing of melamine was done with caffeic acid as a reducing agent which confirms the role of caffeic acid a major constituent of Parthenium leaf extract for interference biosynthesis based sensing. Melamine is detected from raw milk by interference biosynthesis based sensing after a facile milk pre-processing step. Thus the method can be converted into a workable handheld prototype for detection of melamine for in-situ field applications.

Reference-Free Damage Identification in Plate-Like Structures Using Lamb-Wave Propagation with Embedded Piezoelectric Sensors

AbstractStructural health monitoring (SHM) has been adopted in the aircraft and civil industries over the last two decades. The ultrasonic guided wave propagation technique is a promising damage detection approach in airplane thin wall structures because of their long distance traveling ability and low attenuation. In fact, by efficiently designing the pattern of sensors one can effectively pick up the changes that happen in propagated signals due to presence of any kind of structural damage. This detection approach could be effectively assisted by numerical simulation techniques like finite-element modeling. To obtain a damage detection algorithm based on instantaneous baseline data, the finite-element technique is employed for simulation of wave propagation in thin wall structures. Also, the influence of artificial crack (cut-damage) on propagated Lamb waves is investigated. An instantaneous baseline damage detection based on cross-correlation (CC) analysis is carried out to detect the damage, and the r...

A highly selective 7-hydroxy-3-methyl-benzoxazinone based fluorescent probe for instant detection of thiophenols in environmental samples

A new 7-hydroxy-3-methyl-benzoxazinone based fluorescent probe for thiophenols has been designed and synthesized. The probe displays highly selective and sensitive detection to thiophenols over other common analytes with instant response and remarkable large Stokes shift. It’s noteworthy that biothiols, aliphatic thiols, and reducing anions do not perturb the sensing of thiophenols. The limit of detection of the probe was calculated as low as 24nM for thiophenols. Finally, the utility of probe was illustrated by the detection of thiophenol in real environmental water samples.

An easy prepared dual-channel chemosensor for selective and instant detection of fluoride based on double Schiff-base

A colorimetric and fluorescent dual-channel fluoride chemosensor N,N′-bis (4-diethylaminosalicylidene) hydrazine (sensor S) bearing two imine groups has been designed and synthesized. This structurally simple probe displays rapid response and high selectivity for fluoride over other common anions (Cl−, Br−, I−, AcO−, H2PO4−, HSO4−, ClO4−, CN− and SCN−) in a highly polar aqueous DMSO solution. Mechanism studies suggested that the sensor firstly combined with F− through hydrogen bonds and then experienced the deprotonation process at higher concentrations of F− anion to the two Ar-OH groups. The detection limit was 5.78×10−7M of F−, which points to the high detection sensitivity. Test strips based on sensor S were fabricated, which could act as a convenient and efficient F− test kit to detect F− for “in-the-field” measurement.

Topic Model Based New Event Detection Within Topics

Traditional new event detection is first proposed by Topic Detection and Tracking and it is actually first event detection. However, one topic usually consists of many events. The automatic instant detection of each event in one topic, not only the first event but also the second, the third and so on, is very useful for users to correctly understand the main development trend of the topic. In this paper, we address the problem of new event detection in one single topic and propose a novel topic model to detect new events along with the topic evolution. Our topic model treats new event detection as novel semantic aspect identification in one topic, rather than measuring the analog degrees between content items by lexical congruence. Besides, it can automatically determine the appropriate number of aspects needed and can naturally adapt dynamic change in the vocabulary along with the topic evolution. We use a sequential Gibbs sampling algorithm for posterior inference, which well realizes the online new event detection. Experiments are presented to show the performance of our proposed technique. It is found that our proposed technique outperforms the comparable techniques in previous work.

Application of Heterogeneous Robotic System for Underwater Oil Spill Scenario

The tragic Deepwater Horizon accident in the Gulf of Mexico in 2010 as well as the increase in deepwater offshore activity have increased public interest in counter-measures available for subsurface releases of hydrocarbons. To arrive at proper contingency planning, response managers urge for a system for instant detection and characterization of accidental releases. Along these lines, this paper describes the application of a heterogeneous robotic system of unmanned vehicles: autonomous underwater vehicle (AUV), unmanned surface vehicle (USV) and unmanned aerial vehicle (UAV) extended with the oil spill numerical modeling, visualisation and decision support capabilities. A first set of field experiments simulating oil spill scenarios with Rhodamine WT was held in Croatia during the early autumn 2014. and the second set of experiments were held in Spain during the summer 2015. The objectives of this experiment were to test: effectiveness of the system for underwater detection of hydrocarbons, heterogeneous multi-vehicle collaborative navigation and communication as well as decision support system, visualisation of the system components and detected spill.

Rapid Detection of Live Versus Dead Bacteria

This paper presents a rapid method of detecting live versus dead pathogenic bacteria. The method combines phage-coated magnetoelastic (ME) biosensors and a wireless planar coil detector, enabling real-time monitoring of the growth and viability of specific bacteria in a nutrient broth. The ME biosensor used in this investigation is composed of a strip-shaped ME resonator (1 mm x 0.2 mm x 30 um) upon which a landscape phage is coated to capture specific bacteria. E2 phage with high binding affinity for Salmonella Typhimurium was used as a model study. The specificity of E2 phage has been reported to be 200 in 108 background bacteria. When the binding of Salmonella occurs, the mass of the biosensor increases, which simultaneously results in a decrease in the biosensor's resonant frequency. Monitoring of this mass-induced resonant frequency change allows for the instantaneous detection and quantification of Salmonella. ME biosensors with a pre-determined resonant frequency were first exposed to a low-concentration Salmonella suspension to capture a small but detectable amount of the bacteria on the sensor surface. The wireless coil detector was then used to measure the resonant frequency changes of the biosensors as a function of time in a nutrient broth. Live cells can grow, while dead ones can't, which leads to distinct differences in the resonant frequency changes over time. Hence, this methodology offers direct, real-time detection, quantification, and viability determination of specific bacteria.

Primordial Black Holes: Observational characteristics of the final evaporation

Many early universe theories predict the creation of Primordial Black Holes (PBHs). PBHs could have masses ranging from the Planck mass to 105 solar masses or higher depending on the size of the universe at formation. A Black Hole (BH) has a Hawking temperature which is inversely proportional to its mass. Hence a sufficiently small BH will quasi-thermally radiate particles at an ever-increasing rate as emission lowers its mass and raises its temperature. The final moments of this evaporation phase should be explosive and its description is dependent on the particle physics model. In this work we investigate the final few seconds of BH evaporation, using the Standard Model and incorporating the most recent Large Hadron Collider (LHC) results, and provide a new parameterization for the instantaneous emission spectrum. We calculate for the first time energy-dependent PBH burst light curves in the GeV/TeV energy range. Moreover, we explore PBH burst search methods and potential observational PBH burst signatures. We have found a unique signature in the PBH burst light curves that may be detectable by GeV/TeV gamma-ray observatories such as the High Altitude Water Cerenkov (HAWC) observatory. The implications of beyond the Standard Model theories on the PBH burst observational characteristics are also discussed, including potential sensitivity of the instantaneous photon detection rate to a squark threshold in the 5–10 TeV range.

The d-Radar: a bistatic system based on conformal arrays

Multifunction radars based on active phased arrays are well known and widely studied systems. The concepts of bistatic architecture, conformal array and digital beam forming (DBF) are combined in this paper to define a novel multifunction radar for point defense. The conical shape of the antenna overcomes the significant limitations in the azimuth coverage of 360° of fixed-faces phased arrays due to the beam scanning up to 45°. The usage of separate transmit/receive arrays and the DBF technique adds the operational flexibility and the possibility of multiple simultaneous functions, with an optimal time-energy resources exploitation. After a short description of its technological demonstrator, some significant design trade-off, and operating aspects of the proposed architecture, called d-Radar, are described, showing the main differences with respect to the classical, four faces, and phased-array multifunction radar architecture. It is described how the operating modes can be made more and more similar to a “staring” or “ubiquitous” radar permitting an instantaneous detection and location of short-range, low-elevation targets for sea and ground operations. Finally, some remarks about the resources management and scheduling are shown with the results from a case of study.

Software Design of Instantaneous Heart Rate Detection Based on Phase Demodulator for Smart Phones

Software Design of Instantaneous Heart Rate Detection Based on Phase Demodulator for Smart Phones

Novel design of non-enzymatic sensor for rapid monitoring of hydrogen peroxide in water matrix

A simple and reliable design of the non-enzymatic sensor capable of instant detection of broad range of hydrogen peroxide (H2O2) concentrations in various water-based matrixes has been presented. Manufacturing of the sensor was based on the manganese dioxide (MnO2)-non-functionalized single walled carbon nanotubes (SWCNTs) - Nafion nanocomposite modified glassy carbon electrode (MnO2/SWCNTs-Nf/GCE). The electrochemical behavior of hydrogen peroxide at this sensitive platform was verified by the cyclic voltammetry and amperometry. The obtained results have demonstrated that the modified GCE exhibited an excellent electrocatalytic activity towards hydrogen peroxide. The parameters related to this sensor, such as amount of MnO2, applied potential and pH value were optimized to attain a broad working linear range 5.0×10−6 to 3.0×10−3M, with detection limit of 0.52×10−6M (17.7ppb) of detection H2O2. Developed electrode was tested for stability and accuracy measurements in environmental/biological conditions, such as pH and interference of common ions, namely calcium, magnesium, nickel, copper, bicarbonate and citrate, showing an excellent stability and repeatability in tested ranges.

Towards a Real-time Measurement Platform for Microgrids in Isolated Communities

This paper describes a platform for obtaining and analyzing real-time measurements in Microgrids. A key building block in this platform is the Empirical Mode Decomposition (EMD) used to analyze the electrical voltage and current waveforms to identify the instantaneous frequency and amplitude of the monocomponents of the original signal. The method was used to analyse the frequency fluctuation and obtain information about the linearity of electrical current and voltage waveforms measured in the field. Comparison between grid-connected and stand-alone microgrid voltage and currents’ monocomponents were conducted. Fluctuations in the grid frequency occurred in both the grid-connected and stand-alone microgrid, but the degree of the observed fluctuations were different, revealing more apparent nonlinear distortions in the latter. The observed instantaneous frequency from the collected data indicates potential nonstationary electrical signals when compared to synthetic data containing periodic signals coming from nonlinear loads. This observation leads us to expect the next generation of real-time measuring devices for the micro power grids to be designed on the principle of instantaneous frequency detection. Further efforts will be directed to a more rigorous characterization of the nonstationary nature of the signals by analyzing more and longer set of data.

A red emitting fluorescent probe for instantaneous sensing of thiophenol in both aqueous medium and living cells with a large Stokes shift

A novel red emitting fluorescent probe for the instantaneous detection of thiophenol has been developed with a large Stokes shift. The successful application of this new probe for thiophenol detection in real water samples and living cells has been demonstrated.

Optimal pinging frequencies in the search for an immobile beacon

ABSTRACTWe consider a search for an immobile object that can only be detected if the searcher is within a given range of the object during one of a finite number of instantaneous detection opportunities; i.e., “pings.” More specifically, motivated by naval searches for battery-powered flight data recorders of missing aircraft, we consider the trade-off between the frequency of pings for an underwater locator beacon and the duration of the search. First, assuming that the search speed is known, we formulate a mathematical model to determine the pinging period that maximizes the probability that the searcher detects the beacon before it stops pinging. Next, we consider generalizations to discrete search speed distributions under a uniform beacon location distribution. Lastly, we present a case study based on the search for Malaysia Airlines Flight 370 that suggests that the industry-standard beacon pinging period—roughly 1 second between pings—is too short.

A Paper‐based Mitochondrial Electrochemical Biosensor for Pesticide Detection

AbstractIn this article, we detail a paper‐based three‐electrode electrochemical biosensor using a mitochondria modified Toray carbon paper working electrode. Cyclic voltammetry performed on the paper‐based biosensor and similar electrodes in a common laboratory setup (not in an integrated paper‐based device) compare favorably. In addition, instant detection of malathion with a detection limit of 20 nM by cyclic voltammetry is demonstrated, showing the device can potentially be used as a portable platform for pesticides detection.

Robust glottal closure instant detection by jointly exploiting stationary wavelet transform and harmonic superposition

This study jointly utilizes stationary wavelet transform (SWT) and harmonic superposition (HS) techniques to locate zero-crossings closely related to glottal closure instants (GCI). The entire process is performed directly on voiced speech signals without referring to the linear prediction residual or voiced source signal derived by inverse filtering. Subsequent to the multi-scale SWT decomposition, a linear phase FIR filter is introduced to translate positive zero-crossings into pulse-like features. While the product across the approximation coefficients in various SWT levels sharpens impulse features, the HS is employed to sieve out the main pulses corresponding GCIs. The advantages of using the proposed SWT---HS scheme for GCI detection are examined using the PTDB-TUG database. Compared with the other two advanced methods, namely the SEDREAMS and ZFR, without the assistance of any refining process the proposed SWT---HS not only renders better accuracy in GCI positioning but exhibits superior robustness against additive noise.

Automated data analysis to rapidly derive and communicate ecological insights from satellite-tag data: a case study of reintroduced red kites.

Analysis of satellite-telemetry data mostly occurs long after it has been collected, due to the time and effort needed to collate and interpret such material. Delayed reporting reduces the usefulness of such data for nature conservation where timely information about animal movements is required. To counter this problem, we present a novel approach which combines automated analysis of satellite-telemetry data with rapid communication of insights derived from such data. A relatively simple algorithm (based on radial and angular velocity calculated from fixes) allowed instantaneous detection of excursions away from settlement areas and automated calculation of home ranges on the remaining data. Automating the detection of both excursions and home-range calculations enabled us to disseminate ecological insights from satellite-tag data instantaneously through a dedicated web portal. The automated analysis, interpretation, and communication of satellite-tag and other ecological data offer clear benefits to nature conservation research and practice.Electronic supplementary materialThe online version of this article (doi:10.1007/s13280-015-0711-3) contains supplementary material, which is available to authorized users.

Dynamic Doppler Frequency Shift Errors: Measurement, Characterization, and Compensation

Positioning calibration under dynamic conditions is becoming increasingly of interest for high precision fields, such as additive manufacturing and semiconductor lithography. Heterodyne interferometry is often used to calibrate a stage’s position because interferometry has a high dynamic range and direct traceability to the meter. When using heterodyne interferometry, filtering is routinely performed to process and determine the measured phase change, which is proportional to the displacement from one target location to another. The filtering in the signal processing introduces a phase delay dependent on the detection frequency, which leads to displacement errors when target velocity is non-constant as is the case in dynamic calibrations. This paper presents a phase delay compensation method by measuring instantaneous detection frequency and solving for the corresponding phase delay in a field-programmable gate array (FPGA) in real time. The FPGA hardware-in-the-loop simulation shows that this method can significantly decrease the displacement error from ±100’s nm to ±3 nm in dynamic cases and it will still keep subnanometer resolution for quasi-static calibrations.