Intensity Probe Research Articles

Active acoustic intensity errors due to contaminating noise

Bias errors for both one and two-dimensional intensity probes have been previously calculated for both the traditional cross-spectral and the Phase and Amplitude Gradient Estimator (PAGE) methods [E. B. Whiting et al., J. Acoust. Soc. Am.142, 2208–2218 (2017); E. B. Whiting, M. S. Thesis (2016)]. Here, these calculations are expanded to include errors due to the source angle relative to the probe and due to contaminating noise. The noise can either be uncorrelated at each microphone or self-correlated, which is modeled as a plane wave with a varying angle of incidence. The errors in both intensity magnitude and direction are dependent on the signal-to-noise ratio (SNR), frequency, source properties, incidence angles, probe configuration, and processing method. The PAGE method is generally found to give more accurate results, though uncorrelated noise with a low SNR can yield large errors. For broadband signals, the PAGE method can be used beyond the spatial Nyquist frequency. [Work supported by NSF.]

Ultracompact Broadband Plasmonic Polarimeter

AbstractPolarization is one of the fundamental properties of light, which is inherited from the vectorial nature of electromagnetic waves. Measuring states of polarizations (SOPs) is widely used for remote sensing applications. A number of ultracompact polarimeters that analyze SOPs at a single detection without splitting of incident beams have been demonstrated recently. However, the development of a broadband polarimeter remains challenging due to the resonant feature of their building blocks. Here, an ultracompact polarimeter that retrieves the SOP of incident light with broad operation bandwidth at near‐infrared wavelengths is proposed. Surface plasmon polaritons (SPPs) excited by X‐shaped aperture arrays are utilized as intensity probes. Full‐Stokes parameters are retrieved by detecting the SPP intensities. The proposed polarimeter is demonstrated experimentally and can measure SOPs at wavelengths from 750 nm to 1050 nm. This work can help to develop more compact polarization‐sensitive optical systems, such as polarimetry, ellipsometry, and optical routers.

Experimental study of breakout noise characteristics of flexible rectangular duct

Abstract Breakout noise is prominent at low frequencies in a rectangular shaped duct due to strong structural–acoustic coupling and is characterized in terms of transverse transmission loss (TTL). The main objective of the present investigation is, to implement intensity based experimental techniques for measuring breakout noise and validate “equivalent unfolded plate” analytical model available in the literature. An experimental test setup is developed to measure input and radiated sound power along with vibration displacement and particle velocity. Using the obtained input and radiated sound power, transverse transmission loss (TTL) and radiation efficiency are calculated. Input sound power is calculated by using an autospectrum of a progressive pressure wave. Radiated sound power is measured using two different methods, namely- intensity probe method (P-P method) and Microflown technique (P-U method). In this present study, numerical model is also developed to predict transverse transmission loss (TTL), radiation efficiency and these results have been corroborated with experimental and analytical results.

High Frequency Antenna Design Challenges for Underwater Communication - An Intensive Probe

High Frequency Antenna Design Challenges for Underwater Communication - An Intensive Probe

Transient-absorption phases with strong probe and pump pulses

The quantum dynamics of a system of Rb atoms, modeled by a V-type three-level system interacting with intense probe and pump pulses, are studied. The time-delay-dependent transient-absorption spectrum of an intense probe pulse is thus predicted, simulating pump-probe experiments in which this is preceded or followed by a strong pump pulse. Numerical results are interpreted in terms of an analytical model based on interaction operators, which quantify the transformation undergone by the system under the action of an intense pulse. The oscillating features of the resulting transient-absorption spectra, due to the coupling of several excited states, are thus interpreted in terms of the atomic population and phase changes imposed by the pump and probe pulses. Strong-field-induced phases and their influence on the resulting transient-absorption spectra are thereby investigated for different values of pump and probe intensities and frequencies, focusing on the atomic properties which are encoded in the absorption line shapes for positive and negative time delays.

Finite element analysis on squeal-noise in railway applications

In this paper, we present the results of an experimental investigation on squeal noise emitted by a disc brake for railway applications. The measurement, that show in an evident manner the onset of instability forms during the braking phase were made on a test-rig in real scale on which we measured by means of a sound intensity probe the noise emitted by the disc brake. By using a Fast Fourier Transform (FFT) we identified the strongest detected frequencies. The aim of this paper is to analyse such phenomena by conducting a Finite Element Analysis (FEA) of the 3D CAD model of the disk modelled in Ansys Workbench FEM software, in order to, better understand the path that leads a stable system to unstable behaviour. The system analysed is composed of a steel disk and four pads made of an array of cylinders made of frictional material. Such pad system has been designed in order to simplify the simulation, assuming that it acts on the disk surface just in some points. The numerical results agree with the experimental ones.

Creativity and the Burden of Thoughts

Abstract The art of creative expression is a mentally tasking endeavour which requires intense probing of the creator’s inward states. Since writers create in solitude and and engage in dialogic strategies in shaping their imagery, they manifest ‘normal’ neurotic episodes, which are privileged as markers of artistic genius. Despair has thus been acknowledged as a significant feature of the creative imagination. Many writers script out their distressed moods, a paradoxical catharsis, in artistic mentation, that has become a major issue in contemporary studies of scriptotherapy, especially in Europe and North America. Studies of psychotherapy have revealed that the art of re-creating agonizing experiences brings mental restoration to the writer. Due to the emotional commitment and spontaneity required, poetry is clearly a convenient literary genre for the exploration of despondency and melancholic depression. However, this subject of poetry therapy has not been given adequate attention in Nigerian literary scholarship. The present study attempts an exemplary ‘poetic-diagnosis’ of melancholia in Wumi Raji’s Rolling Dreams. The article relies on psychoanalysis, a theory of the mind, deployed for the analysis of the abject imagery of the poems, and on deconstructionist theory, for autonomous and polysemous investigation of the melancholic poetic canvas of the collection.

Sound intensity probe for ultrasonic field in water using light-emitting diodes and piezoelectric elements

The sound intensity vector provides useful information on the state of an ultrasonic field in water, since sound intensity is a vector quantity expressing the direction and magnitude of the sound field. In the previous studies on sound intensity measurement in water, conventional piezoelectric sensors and metal cables were used, and the transmission distance was limited. A new configuration of a sound intensity probe suitable for ultrasonic measurement in water is proposed and constructed for trial in this study. The probe consists of light-emitting diodes and piezoelectric elements, and the output signals are transmitted through fiber optic cables as intensity-modulated light. Sound intensity measurements of a 26 kHz ultrasonic field in water are demonstrated. The difference in the intensity vector state between the water tank with and without sound-absorbing material on its walls was successfully observed.

Pavement noise measurements in Poland

The objective of this study is to investigate the feasibility of the On-Board Sound Intensity (OBSI) system to measure tire-pavement noise in Poland. In general, sources of noise emitted by the modern vehicles are the propulsion noise, aerodynamic resistance and noise generated at the tire-pavement interface. In order to capture tire-pavement noise, the OBSI system uses a noise intensity probe installed in the close proximity of that interface. In this study, OBSI measurements were performed at different types of pavement surfaces such as stone mastic asphalt (SMA), regular asphalt concrete (HMA) as well as Portland cement concrete (PCC). The influence of several necessary OBSI measurement conditions were recognized as: testing speed, air temperature, tire pressure and tire type. The results of this study demonstrate that the OBSI system is a viable and robust tool that can be used for the quality evaluation of newly built asphalt pavements in Poland. It can be also applied to generate reliable input parameters for the noise propagation models that are used to assess the environmental impact of new and existing highway corridors.

Gold nanoparticle labeling with tyramide signal amplification for highly sensitive detection of alpha fetoprotein in human serum by ICP-MS

In this work, we developed an immunoassay based on tyramide signal amplification (TSA) and gold nanoparticles (Au NPs) labeling for highly sensitive detection of alpha fetoprotein (AFP) by inductively coupled plasma mass spectrometry (ICP-MS). AFP was captured by anti-AFP1 coating on the 96-well plate and labeled by anti-AFP2-horseradish peroxidase (HRP), in which the HRP can catalyze the deposition of biotinylated tyramine on the nearby protein. Then the streptavidin (SA)-Au NPs was labeled on the deposited biotinylated tyramine as the intensive signal probe for ICP-MS measurement. Under the optimal experimental conditions, the limit of detection of the developed method for AFP was 1.85pg/mL and the linear range was 0.005–2ng/mL. The relative standard deviation for seven replicate detections of 0.01ng/mL AFP was 5.2%. The proposed method was successfully applied to the detection of AFP in human serum with good recoveries. This strategy is highly sensitive and easy to operate, and can be extended to the sensitive detection of other biomolecules in human serum.

Shigaraki UAV-Radar Experiment (ShUREX): overview of the campaign with some preliminary results

The Shigaraki unmanned aerial vehicle (UAV)-Radar Experiment (ShUREX) is an international (USA-Japan-France) observational campaign, whose overarching goal is to demonstrate the utility of small, lightweight, inexpensive, autonomous UAVs in probing and monitoring the lower troposphere and to promote synergistic use of UAVs and very high frequency (VHF) radars. The 2-week campaign lasting from June 1 to June 14, 2015, was carried out at the Middle and Upper Atmosphere (MU) Observatory in Shigaraki, Japan. During the campaign, the DataHawk UAV, developed at the University of Colorado, Boulder, and equipped with high-frequency response cold wire and pitot tube sensors (as well as an iMET radiosonde), was flown near and over the VHF-band MU radar. Measurements in the atmospheric column in the immediate vicinity of the radar were obtained. Simultaneous and continuous operation of the radar in range imaging mode enabled fine-scale structures in the atmosphere to be visualized by the radar. It also permitted the UAV to be commanded to sample interesting structures, guided in near real time by the radar images. This overview provides a description of the ShUREX campaign and some interesting but preliminary results of the very first simultaneous and intensive probing of turbulent structures by UAVs and the MU radar. The campaign demonstrated the validity and utility of the radar range imaging technique in obtaining very high vertical resolution (~20 m) images of echo power in the atmospheric column, which display evolving fine-scale atmospheric structures in unprecedented detail. The campaign also permitted for the very first time the evaluation of the consistency of turbulent kinetic energy dissipation rates in turbulent structures inferred from the spectral broadening of the backscattered radar signal and direct, in situ measurements by the high-frequency response velocity sensor on the UAV. The data also enabled other turbulence parameters such as the temperature structure function parameter {C}_T^2 and refractive index structure function parameter {C}_n^2 to be measured by sensors on the UAV, along with radar-inferred refractive index structure function parameter {C}_{n,mathrm{radar}}^2 . The comprehensive dataset collected during the campaign (from the radar, the UAV, the boundary layer lidar, the ceilometer, and radiosondes) is expected to help obtain a better understanding of turbulent atmospheric structures, as well as arrive at a better interpretation of the radar data.

Upconverting luminescence based dual-modal temperature sensing for Yb3+/Er3+/Tm3+: YF3 nanocrystals embedded glass ceramic

Yb3+/Er3+/Tm3+ doped transparent glass ceramic containing orthorhombic YF3 nanoparticles was successfully synthesized by a melt-quenching method. After glass crystallization, tremendously enhanced (about 5000 times) upconversion luminescence, obvious Start-splitting of emission bands as well as long upconversion lifetimes of Er3+/Tm3+ confirmed the incorporation of lanthanide activators into precipitated YF3 crystalline environment with low phonon energy. Furthermore, temperature-dependent upconversion luminescence behaviors of glass ceramic were systematically investigated to explore its possible application as optical thermometric medium. Impressively, both fluorescence intensity ratio of Er3+: 2H11/2→4I15/2 transition to Er3+: 4S3/2→4I15/2 one and fluorescence intensity ratio of Tm3+: 3F2,3→3H6 transition to the combined Tm3+: 1G4→3F4/Er3+: 4F9/2→4I15/2 ones were demonstrated to be applicable as temperature probes, enabling dual-modal temperature sensing. Finally, the thermal effect induced by the irradiation of 980nm laser was found to be negligible in the glass ceramic sample, being beneficial to gain intense and precise probing signal and detect temperature accurately.

Experimental vibro-acoustic analysis of the gear rattle induced by multi-harmonic excitation

The paper reports a wide vibro-acoustic experimental investigation of the gear rattle phenomenon induced by multi-harmonic excitation. The analysis is performed by using different measurement techniques which allow some of the significant parameters in this type of investigation to be acquired on a specific test rig: the angular rotations of the gears by using encoders; the accelerations obtained from a triaxial accelerometer; the sound pressure level determined by employing both acoustic microphones; the correct evaluation of the acoustic sources by utilizing a p–v sound intensity probe. Performance indices were adopted to compare the dynamic behaviours of the system with respect to some parameters, such as the speed of the pinion, the fluctuations in the speed of the pinion and the lubrication conditions. The results of the comparative analysis show very good agreement between the vibro-acoustic measurements and the results from the encoder-based method; this has helped us to interpret the physical behaviour of the gear pair with respect to the impacts occurring between the teeth during the different phases of the phenomenon. Moreover, the study indicates interesting aspects of the effects of multi-harmonic excitation on the rattle phenomenon, with particular attention to the influence of lubrication on the reduction in the rattle noise.

Source localization with three-dimensional sound intensity probe with high precision

When an array module measuring three-dimensional sound intensity is employed for detecting the sound source, a compact space usage and small number of sensors are advantageous than the other source localization methods. However, because of severe bias errors, it has not been popular. We analyze the major sources of bias estimation error and seek for the compensation method. Spectral bias error is due to the reflected signal from the environment, which is proportional to the difference of distance between direct and reflective paths. Spatial bias error is due to the inhomogeneous directivity of the intensity module stemming from discrete arrangement of sensors on the hypothetical sphere surrounding sensors. Simulation with changing the source direction by 1 deg. in spherical angle can generate an error map for all incidence angles. A measurement is conducted using a tetrahedral intensity module with 30 mm spacing for the compensation of errors. Low pass filtering of the cross spectral density function is used for the spectral bias error, and spherical error map is used for the directional bias error. By compensating such bias errors, it is shown that the localization errors of all bearing angles are less than 1° in an anechoic chamber when kd<1.1.

Bias error comparison for plane-wave acoustic intensity using cross-spectral and phase-and-amplitude-gradient-estimator methods

Acoustic vector intensity relies on the product of the acoustic pressure and particle velocity. The particle velocity is typically approximated via Euler’s equation using the gradient of the complex pressure across closely spaced microphones, which is traditionally found using the cross-spectral density. In contrast, the phase-and-amplitude-gradient-estimator (PAGE) method [Thomas et al., J. Acoust. Soc. Am., 137, 3366-3376 (2015)] relies on gradients of pressure magnitude and phase. For a broadband source this allows for the phase to be unwrapped, which extends the usable bandwidth of the intensity calculation well above the spatial Nyquist frequency. The benefits of the PAGE method are evident in plane wave tube measurements in which microphones spaced 90 cm apart yield accurate intensity values at frequencies at least ten times the spatial Nyquist frequency. This represents an increase in bandwidth of 30 times over the traditional method. The bias errors for the traditional method for calculating acoustic intensity are reviewed and compared with the bias errors for the PAGE method for the case of both two and three microphone intensity probes in a plane-wave tube environment. [Work supported by the National Science Foundation.]

Sesquiterpenes evaluation on Schistosoma mansoni: Survival, excretory system and membrane integrity

The main challenge in schistosomiasis control has been the emergence of drug-resistant parasites. Since the 1970 tm)s, praziquantel (PZQ) is the single drug for treatment. This fact highlights the importance to research news chemotherapeutic agents. In the last years, S. mansoni excretory system and tegument have been major targets for drug development. The purpose of this study was to evaluate the effect of sesquiterpenes, alpha-humulene and trans-caryophyllene on S. mansoni survival, excretory system and membrane integrity, after in vitro exposure. The in vitro studies, showed that sesquiterpenes reduced egg production and motor activity of worms at sublethal concentrations, and caused death in a concentration-dependent manner (100 and 200α/4g/mL). Tegumental analysis by Scanning Electron Microscopy (SEM), showed tegument damage. Additionally, it was possible to observe lesions, evidenced by intense marking trough Hoechst probe, in the tegument and suckers of worms exposed to 200α/4g/mL. In this study, we also showed that resorufin is only capable of identifying the interaction of sesquiterpenes in males excretory system, Pgp expression and inferring that females are more tolerant to treatments. Thus, the present study results contribute to an understanding of alpha-humulene and trans-caryophyllene effect over these targets, contributing for the development of schistosomicidal drugs.

Numerically analyzed spectral and temporal management of all-optical switching based on chalcogenide bistable fiber Bragg gratings

All-optical switching in nonlinear chalcogenide fiber Bragg gratings (FBG) can be achieved thanks to the third-order nonlinear optical parameters of chalcogenide glasses. Spectral and temporal characteristics of these gratings are shown. Two principal nonlinear effects with similar power requirements can result in the bistable transmission/reflection of an input optical pulse. In the self-phase modulation (SPM) regime switching is achieved by the intense probe pulse itself. Using cross-phase modulation (XPM) a strong pump alters the FBG refractive index experienced by a weak probe pulse. As a result of this the detuning of the probe pulse from the center of the photonic band gap occurs. This paper is devoted to the comparison of SPM and XPM switching simulated using the time-domain transfer matrix method. Further we present the results of numerical investigation of the effect of modulation instability formed in nonlinear FBGs. The modulation instability occurs if the grating response time is lower than the transit time of the pulse through the grating. Possibilities of the successful elimination of the output pulse degradation via the modulation instability under different conditions implemented into numerical experiments are discussed.

A Comprehensive Study of Photorefractive Properties in Poly(ethylene glycol) Dimethacrylate- Ionic Liquid Composites.

A detailed investigation of the recording, as well as the readout of transmission gratings in composites of poly(ethylene glycol) dimethacrylate (PEGDMA) and ionic liquids is presented. Gratings with a period of about 5.8 micrometers were recorded using a two-wave mixing technique with a coherent laser beam of a 355-nm wavelength. A series of samples with grating thicknesses micrometers, each for two different exposure times, was prepared. The recording kinetics, as well as the post-exposure properties of the gratings were monitored by diffracting a low intensity probe beam at a wavelength of 633 nm for Bragg incidence. To obtain a complete characterization, two-beam coupling experiments were conducted to clarify the type and the strength of the recorded gratings. Finally, the diffraction efficiency was measured as a function of the readout angle at different post-exposure times. We found that, depending on the parameters, different grating types (pure phase and/or mixed) are generated, and at elevated thicknesses, strong light-induced scattering develops. The measured angular dependence of the diffraction efficiency can be fitted using a five-wave coupling theory assuming an attenuation of the gratings along the thickness. For grating thicknesses larger than 85 microns, light-induced scattering becomes increasingly important. The latter is an obstacle for recording thicker holograms, as it destroys the recording interference pattern with increasing sample depth. The obtained results are valuable in particular when considering PEGDMA-ionic liquid composites in the synthesis of advanced polymer composites for applications, such as biomaterials, conductive polymers and holographic storage materials.

3D Acoustic Field Intensity Probe Design and Measurements

Abstract The aim of this paper is two-fold. First, some basic notions on acoustic field intensity and its measurement are shortly recalled. Then, the equipment and the measurement procedure used in the sound intensity in the performed research study are described. The second goal is to present details of the design of the engineered 3D intensity probe, as well as the algorithms developed and applied for that purpose. Results of the intensity probe measurements along with the calibration procedure are then contained and discussed. Comparison between the engineered and the reference commercial probe confirms that the designed construction is applicable to the sound field intensity measurements with a sufficient effectiveness.

Proposal and proof-of-principle demonstration of non-destructive detection of photonic qubits using a Tm:LiNbO3 waveguide.

Non-destructive detection of photonic qubits is an enabling technology for quantum information processing and quantum communication. For practical applications, such as quantum repeaters and networks, it is desirable to implement such detection in a way that allows some form of multiplexing as well as easy integration with other components such as solid-state quantum memories. Here, we propose an approach to non-destructive photonic qubit detection that promises to have all the mentioned features. Mediated by an impurity-doped crystal, a signal photon in an arbitrary time-bin qubit state modulates the phase of an intense probe pulse that is stored during the interaction. Using a thulium-doped waveguide in LiNbO3, we perform a proof-of-principle experiment with macroscopic signal pulses, demonstrating the expected cross-phase modulation as well as the ability to preserve the coherence between temporal modes. Our findings open the path to a new key component of quantum photonics based on rare-earth-ion-doped crystals.