Sound Profile Research Articles

Crustal Structure of the Chuan‐Dian Block Revealed by Deep Seismic Sounding and its Implications for the Outward Expansion of the East Tibetan Plateau

AbstractThe Chuan‐Dian Block (CDB) is located in the southeastern margin of the Tibetan Plateau, with a complex geological structure and active regional faults. The present tectonic condition with strong crustal deformation is closely related to the ongoing collision of the India and Eurasia plates since 65 Ma. The study of the crustal structure of this area is key to revealing the evolution and deep geodynamics of the lateral collision zone of the Tibetan Plateau. Deep seismic sounding is the most efficient method with which to unravel the velocity structure of the whole crust. Since the 1980s, 19 deep seismic sounding profiles have been captured within the CDB area. In this study, we systematically integrate the research results of the 19 profiles in this area, then image the 3D crustal velocity, by sampling with a 5 km spacing and 2D/3D Kriging interpolation. The results show the following. (1) The Moho depth in the study area deepens from 30 km in the south to 66 km in the north, whereas there is no apparent variation from west to east. The Pn wave velocity is higher in stable tectonic units, such as 7.95 km/s in the Lanping‐Simao block and 7.94 km/s in the western margin of the Yangtze block, than in active or mobile tectonic units, such as 7.81 km/s in the Baoshan block, 7.72 km/s in the Tengchong block and 7.82 km/s in the Zhongdian block. (2) The crustal nature of the Tengchong block, the northern Lanping‐Simao block and the Zhongdian block reflects a type of orogenic belt, having relatively strong tectonic activities, whereas the crustal nature of the central Lanping‐Simao block and the western margin of the Yangtze block represents a type of platform. The different features of the upper‐middle crust velocity, Moho depth and Pn wave velocity to both sides of the Red River fault zone and the Xianshuihe fault zone, reflect that they are clearly ultra‐crustal. (3) Based on the distribution of the low velocity zones in the crust, the crustal material of the Tibetan Plateau is flowing in a NW–SE direction to the north of 26°N and to the west of 101°E, then diverting to flowing eastwards to the east of 101°E.

Resilient model of multi-UUVs cooperative localization for detection of sensor fault and outliers

Unmanned underwater vehicles (UUVs) cooperative localization technology has become an emerging research topic, which can extend the space-time datum of satellite navigation to seafloor, and provide high-precision location for UUVs to carry out large-area marine environment investigation, exploration and search. Nevertheless, the complex underwater environment makes it impossible to avoid the abnormal condition for sensor fault and outliers. In this contribution, a novel resilient model of multi-UUVs cooperative localization is established. The three-dimensional system model and measurement model are constructed based on the inertial navigation system, and the deviation between multi-sensors are defined and corrected. Furthermore, the resilient factor is proposed based on the normalized prediction residual, and the resilient fusion of UUVs cooperative localization is realized by three steps, i.e., (1) Dynamic resilient fusion of single UUV; (2) Static resilient fusion of single UUV; (3) Static resilient fusion of UUVs cluster. In order to verify the effectiveness of the proposed resilient model, the sound velocity profile in the Nankai trough is selected. The experimental results show that the proposed resilient model of UUVs cooperative localization can accurately detect the abnormal observations and significantly improve the reliability of UUVs cooperative localization.

Tracking Atmospheric Moisture Changes in Convective Storm Environments Using GEO ABI and LEO CrIS Data Fusion

The synergistic use of data from advanced space-borne instruments of different designs onboard different satellite platforms with different orbital tracks provides advantages in various applications over the use of individual data sets alone. For example, high vertical resolution sounding profiles from advanced sounders like CrIS (Cross-track Infrared Sounder) in a low Earth orbit (LEO) and a high horizontal plus temporal resolution radiance measurements from geostationary (GEO) imagers like ABI (Advanced Baseline Imager) can be effectively combined to benefit severe weather monitoring, prediction, and warning systems. The spatial and temporal fusion approach allows LEO products, such as atmospheric moisture, to be created with increased spatial detail at every GEO measurement time, generating a GEO hyperspectral sounder-like perspective. To demonstrate the potential benefit of a GEO and LEO (i.e., ABI and CrIS) data fusion to real-time applications, time sequences of the moisture profile fusion results are presented in two case studies, namely a tornado outbreak in Nebraska on 5 May 2021 and a severe storm occurrence in Texas on 24 May 2022. The implications of the fusion results for nowcasting and warning operations via comparisons to numerical model forecasts and weather radar reflectivity data are discussed.

The Big Unknown: Who Grows Cannabis in Albania?—a Case-based Approach to the Cannabis Farmers in Albania

This paper used publicly available data, such as the analysis of 103 court cases to make a profile of those convicted for cannabis cultivation in Albania. There are multiple reports on drugs and organized crime in Albania which provide information on the seizures of illicit substances, law enforcement operations and organized criminal groups. Reports position Albanian organized crime groups in the international drug market. However, there is little or no data on who the actual producers are. There are no household studies or crop monitoring surveys for Albania, resulting in a big data gap around drug crop cultivation. Despite the availability of public data on the prosecution of drug-related crimes, there is no sound analysis and profiling of cannabis growers, such as their educational level, employment status, income level, gender or living conditions. Where does illicit cannabis cultivation take place, indoors or outdoors, and to what extent? Is cultivation taking place in privately owned or public fields? How big is the area of land where cannabis is cultivated, and with how many plants? The purpose of this paper is to identify the cannabis hotspots of Albania and the profile of those who illicitly cultivated cannabis between 2010–2020, taking into account their age, gender, civil status, educational level, income level etc. and conditions under which they cultivate. In order to understand the drug cultivation in Albania, a historical snapshot will be presented. For this paper, all publicly available data was used, together with analyses of 103 court cases, to gain a better understanding of the profile of those who cultivate cannabis, making this research unique for Albania. This paper presents new evidence for policy makers to address the root causes of illicit cultivation of cannabis in Albania. This paper reconfirms the thesis that those involved in drug crop cultivation are driven by economic factors, lack of market access, lack of education and lack of access to social services.

Observational study of the influences of thermal and dynamic boundary layer on the vertical distribution of black carbon aerosol in ShouXian county in wintertime, 2016

Using vertical observation data of black carbon aerosol and meteorological parameters in the ShouXian area of Anhui Province from 14 December 2016 to 3 January 2017, the thermal and dynamic effects of the boundary layer on the vertical distribution structure of black carbon were studied. The results show that 1) of 82 vertical sounding profiles obtained during the observation period, there were 72 boundary layer sounding profiles dominated by heat and 10 profiles dominated by dynamics. 2) When thermal effects were dominant, the concentration of black carbon aerosol was significantly affected by diurnal changes in the boundary layer. In the unstable boundary layer, black carbon aerosol was uniformly distributed in the vertical direction; during the transition from an unstable to a stable boundary layer, the concentrations of black carbon aerosol were significantly higher in the lower layer than in the upper layer; in the stable boundary layer, the concentrations of black carbon aerosol decreased continuously with height; and during the transition from a stable to an unstable boundary layer, the black carbon aerosol concentrations exhibited high values in the upper layer, with the concentration difference reaching 4 μg m−3. 3) When the dynamic effect was dominant, the structure of the vertical distribution of black carbon aerosol was affected by wind and by diurnal changes in the boundary layer simultaneously. The high winds (>4 m/s) removed the black carbon aerosol. In the unstable boundary layer, the black carbon aerosol uniformly distributed in the vertical direction had significantly lower concentrations in the high-wind range; when stable boundary layers occurred and during transitions from stable to unstable boundary layers, the black carbon aerosol concentrations were higher in the lower layer and lower in the upper layer. The stratification was more obvious than that observed under thermal control.

In-situ emulsification synergistic self-profile control system on heavy oil reservoir development: Prescription construction and EOR mechanism investigation

Water flooding is a vital method used for developing heavy oil reservoirs. However, the fingering phenomenon is common because of the significant difference in water-oil mobility ratio, resulting in limited sweep efficiency and a low cumulative recovery factor. Viscosity reduction through emulsification and profile control using foam is of great potential to enhance oil recovery (EOR) in water flooding of general heavy oil reservoirs. The present work constructed an effective in-situ emulsification synergistic self-adjusting profile control system based on these two EOR pathways and investigated the performances of the proposed system, such as viscosity reduction via emulsification, foam plugging, and synergistic oil displacement. The results show that sodium octadecyl phenol polyoxyethylene ether sulfonate-4 (JNPM) with sound viscosity reduction, profile control, and oil displacement effects were synthesized through chlorination and sulfonation reactions. JNPM can reduce the oil-water interfacial tension and promote the emulsification of heavy oil in an effective way. It forms an unstable micron-scale oil-in-water emulsion, which is easy to induce oil-water separation of the produced fluid. The reduction in viscosity for JNPM exceeds 90%, whereas the foam produced by JNPM can adequately reduce the relative permeability of the displacement medium, and it is found that the resistance factor is higher than 25. The EOR mechanisms of JNPM include the following aspects. JNPM foam fluid has a stable plugging capability on the channeling channels of the displacement media, such as water and gas, which forcefully increases the residual oil sweep efficiency. JNPM peels off the residual oil on the pore wall through emulsification, thus the oil washing efficiency is improved. The droplets of oil formed by emulsification can block the channeling channels through the Jamin effect to further increase the conformance efficiency. In addition, when the small droplets deform and pass through the pores, they can sweep away the residual oil by dragging and entraining effects. The contributions of viscosity-reducing emulsification and foam plugging to EOR are 26.4% and 12.0% respectively during the viscosity-reducing foam flooding of JNPM.

On the application of sound radiation force for focusing of powder stream in directed energy deposition

One of the challenges in directed energy deposition via powder feeding (DED-PF) is the powder stream divergence that results in low catchment efficiency (i.e., the fraction of particles added to the melt pool). This article introduces a new ultrasound-based powder focusing method referred to as ultrasound particle lensing (UPL), tailored for powder used in DED-PF. The method uses an ultrasound phased array to produce a small volume of high-intensity ultrasound with the required period averaged sound intensity profile. UPL was used to acoustically focus streams of Ti64 and SS 316L particles with an average size of 89μm and a particle speed of 0.6 m/s, exiting from a DED-PF nozzle analog. The e−1 powder stream widths downstream of the resulting force fields for both materials were reduced by 30%. The experimental results closely match Lagrangian and Eulerian simulations of the process. This novel setup offers the possibility of fast control of the powder stream divergence angle and effective diameter in the process zone during the DED-PF process. This will in turn improve the feature resolution and catchment efficiency of the process.

Investigation on beamforming solution for multi-receiver synthetic aperture sonar using CW pulse with sound velocity profiles in Vietnam’s sea

This paper proposes a novel beamforming solution for multi-receiver synthetic aperture sonar (SAS), which uses gated continuous-wave (CW) pulses, based on the average value of equivalent sound velocity (ESV) when considering the change of the sound velocity with depth. The main beam can be steered to desirable positions with the proposed solution. Besides, the computation time for the phase distribution from the proposed solution reduces compared with the conventional solution by dividing the propagation trajectory into straight lines, where the sound velocity is unchanged. The effectiveness of the proposed solution is validated and evaluated by the results of the beam pattern and the time for determining the phase distribution with the sound velocity profiles (SVPs) in Vietnam’s sea.

Impacts of Radio Occultation Data on Typhoon Forecasts as Explored by the Global MPAS-GSI System

Global Navigation Satellite System (GNSS) radio occultation (RO) provides plentiful sounding profiles over regions lacking conventional observations. The Gridpoint Statistical Interpolation (GSI) hybrid system for assimilating RO data is integrated in this study with the Model for Prediction Across Scales–Atmosphere (MPAS) to improve tropical cyclone forecasts. After the MPAS-GSI assimilation cycles, dynamical vortex initialization (DVI) that may effectively spin up the initial inner typhoon vortex through cycled model integration is implemented to improve the initial analysis fit to the best track position as well as maximum wind or pressure intensity for Typhoon Nepartak (2016) that moved northwestward toward southern Taiwan. During the cycling assimilation, assimilation with RO data improves the temperature and moisture analysis, and largely reduces the forecast errors compared to those without RO data assimilation. The two RO operators that assimilate local bending angle or refractivity produce similar analyses, but the temperature and moisture increments from bending angle assimilation are slightly larger than those from refractivity assimilation. The MPAS forecasts at 60-15 km resolution show that the typhoon track prediction is improved with RO data, especially using bending angle data. The reduction in track deviations is explained by the wavenumber-one potential vorticity budget for several forecasts associated with the track deflection near southern Taiwan. Assimilation of RO data has fewer impacts on the typhoon intensity forecast compared to the DVI that largely improves the initial and thus forecasted intensity of the typhoon but at the cost of a slightly degraded track. Use of the enhanced 3 km resolution in the typhoon path also further improved the forecasts with and without the DVI. The feasible performance of the MPAS-GSI system with the RO data impact is also illustrated for Typhoon Mitag (2019), that passed around northern Taiwan.

Sound waves in a tube: measuring sound pressure profiles using smartphones

We present an experiment designed to study standing waves in a tube with one closed end. Two smartphones are used, one to emit a sound signal with a chosen frequency and another equipped with a microphone to detect the sound pressure level inside the tube. Due to the finite diameter of the tube, the standing wave node (or antinode) appears slightly outside of its opened end so the end correction is applied. Results show a good agreement with the theory, making this proposal suitable to be applied to secondary school classes. It is a low cost experiment and has the potential to increase the understanding of this physical phenomenon by secondary students.

Molnupiravir for the treatment of COVID-19.

Molnupiravir (MK-4482, EIDD-2801) is a promising broad-spectrum experimental antiviral developed by Merck & Co. It is a nucleoside analogue prodrug that undergoes rapid conversion into nucleoside triphosphate (NTP) by intracellular metabolic processes. NTP inhibits viral polymerase by acting as an alternative substrate. Molnupiravir was initially developed to treat influenza and Venezuelan equine encephalitis virus (VEEV) infection as it exerts its antiviral activity by inhibiting RNA-dependent RNA polymerase (RdRp). Currently, it is being developed for the treatment of SARS-CoV-2 infection. Molnupiravir has demonstrated potent in vitro antiviral activity against positive-sense RNA viruses including influenza viruses, SARS-CoV, SARS-CoV-2 and MERS-CoV with low cytotoxicity and a high resistance barrier. Molnupiravir has been evaluated in phase I, II and III trials where it has demonstrated good efficacy, dose-dependent pharmacokinetics and a sound safety profile. In an interim analysis of a phase III study, treatment with molnupiravir reduced the risk of hospitalization or death by 50% in patients with COVID-19; in the final analysis, the reduction was 30%. On the basis of positive results in clinical trials, molnupiravir has been authorized for emergency use by the U.K. Medicines and Healthcare products Regulatory Agency (MHRA) and the U.S. Food and Drug Administration (FDA) in adults with mild to moderate COVID-19.

Оцінка міцності та надійності автотранспортних засобів

At present, the issue of ensuring the strength and reliability of wheeled vehicles, the creation of which requires compliance with all modern requirements, has not been fully resolved. In this regard, improving the methodology for assessing the strength and reliability of vehicles is an urgent task, the solution of which involves finding answers to the following questions: the choice of a rational version of the bearing system and economically sound profiles; selection of materials with appropriate physical and mechanical characteristics, etc. The choice of a rational variant of the load-bearing system of frame structures of vehicles requires a comparative assessment of possible options at all stages of design work. The load-bearing structures of vehicles are statically uncertain. Therefore, the process of assessing the strength and reliability of vehicles with different types of design schemes is a complex task, which today does not have a single methodological solution. In order to solve this problem, the model of the stress-strain state of the spatially loaded frame structure of the HESSTON S 125 solid fertilizer spreader is considered by a modified method of minimum potential deformation energy of structural structures using the Heaviside function. The frame is a welded load-bearing structure consisting of three longitudinal spars connected by a front beam and crossbars. Carrying out the correct and rational analysis of the stress-strain state of such a bearing system is possible only with the use of a modified method of minimum potential deformation energy. As a result of modeling, recommendations were obtained for the rational design of components and components of wheeled vehicles with increased reliability while reducing material consumption. Ultimately, this leads to an increase in their strength and reliability while reducing material consumption.

Modelling vibro–acoustic response of lightweight square aluminium panel influenced by sound source locations for active control

This paper uses numerical approach to give insight into the structural–acoustic response of a lightweight square aluminium panel. It takes into consideration different locations of a primary sound source in an acoustic medium and how these locations influence the response of the structural panel. Finite element method as well as the first-order deformation theory are employed for constructing the numerical model. Experimental measurements of the mode shapes and velocity frequency response of the vibrating panel are used to validate the results of the finite element model. Furthermore, vibro-acoustic emission indexes such as sound transmission loss, sound pressure level and far-field directivity of sound pressure are obtained numerically. The results show that different locations of the primary sound source significantly influence the response of the structural panel to reduce noise. Sound source typically positioned close to the structural panel lowers the efficiency of the vibrating panel to reduce noise. Moreover, the sound distribution profiles at the radiated end of the vibrating panel for the different locations of the sound source are investigated. The study shows that the variation of the zones of quiet, vibro-acoustic emission parameters and sound distribution profiles obtained can provide vital information about the best positioning of structural source for both active vibration and noise control.

Geophysical Implications for Prospective Prediction of Copper Polymetallic Ore Bodies: Northern Margin of Alxa Block, China

The Alxa Block is located in the middle part of the Central Asian orogenic belt, which is the coupling belt of the North China, Tarim, and Kazakhstan Plates. The east–west-trending deep faults control stratigraphic distribution and magmatic activity in the region. To detect the EW-trending ore-controlling deep structures, a 440 km NS section of magnetotelluric sounding was conducted from Minle to Ejinaqi. The phase tensor and electrical principal axis were analyzed based on the measured data to build the exploration model. The electrical structure model along the section was obtained using nonlinear conjugate gradient (NLCG) 2D inversion. Combined with the geological, geophysical, and deposit distribution characteristics in the area, the comprehensive study of magnetotelluric sounding profile shows that the resistivity presents as zoned along the profile. The Engelwusu ophiolite mélange belt is stacked in clumps with high and low resistivity, indicating that the northern margin of the Engelwusu Belt subducts below the high-resistivity zone, representing the passive continental margin. The southern end of the Engelwusu ophiolite belt is primarily the prospecting potential area for copper–gold deposits, whereas the northern end of the Engelwusu ophiolite belt corresponds to copper polymetallic deposits.

A Self-Constraint Underwater Positioning Method without the Assistance of Measured Sound Velocity Profile

Aiming at the problem that lack of the measured sound velocity profile (SVP) leads to the unreliable underwater positioning solution, this paper proposed an efficient underwater positioning method by the self-constraint conditions of water depth and sound velocity gradient. To construct the depth constraint condition, the sound propagation distance error model is deduced by acoustic ray tracing, and the sound vertical propagation error model related to the incident angle and sound velocity error is given firstly. By fitting the vertical propagation error model, the reference depth is solved, and the vertical propagation distances between the transducer and the underwater control points of all observation epochs are gotten. Then with the solved vertical distance of each epoch and the sound velocity gradient from neighbor SVPs as the constraint conditions, the SVP is retrieved by the simulated annealing (SA) algorithm. With the retrieved SVP, the underwater positioning can be performed when the measured SVP is absent. The proposed method was verified by an experiment in the 3000 m depth water area of the South China Sea. The results achieved 2.07 m/s of standard deviation of the SVP inversion, centimeter-level horizontal positioning accuracy and 0.54 m of vertical positioning accuracy under the circumstance of lack of SVP measurement.

Vertical electrical sounding data inversion using continuous ant colony optimization algorithm: A case study from Hassi R'Mel, Algeria

ABSTRACTAmong the existing geophysical methods, the vertical electrical sounding remains a fast and economical way to detect groundwater resources. However, the interpretation of the vertical electrical sounding data often suffers from non‐uniqueness due to the ill‐posed nature of the inverse problem. In recent years, metaheuristic algorithms have been successfully used for solving ill‐conditioned and ill‐posed problems. This work presents a scheme that uses the continuous ant colony optimization (ACOR) technique to invert vertical electrical sounding data. The ACOR is a global search algorithm that explores and finds the globally optimal solution over a search space by mimicking the behaviour of biological ants. The development of this algorithm was due to the requirement to interpret a set of vertical electrical sounding collected at the region of Hassi R'Mel (Algerian Sahara). The area has a particular geological/geoelectrical structure, which renders the interpretation of vertical electrical sounding challenging as standard inversion approaches tend to fail to recover a reliable resistivity model. The ACOR algorithm was initially tested with synthetic data from models simulating the geological/hydrogeological structure of the studied area. The results verified the robustness and stability of the ACOR algorithm even in the presence of a high level of noise. Furthermore, the tests indicated that the ACOR algorithm performed better when compared to other inversion techniques for this particular geoelectrical structure. Five vertical electrical sounding profiles using a Schlumberger array collected in the region of Hassi R'Mel were inverted using the ACOR algorithm. The models confirmed the presence of the two central aquifer systems and showed the geometry of the aquifer with the most favourable conditions for water accumulations.

Fast Melt Cocoa Butter Tablet: Effect of Waxes, Starch, and PEG 6000 on Physical Properties of the Preparation.

A fast melt tablet (FMT) is well regarded as an alternative delivery system that might help resolve a patient’s non-compliance issue. The main objective of this study was to develop a cocoa butter-based FMT. Additives, namely 5–15% of PEG 6000, beeswax, paraffin wax, and corn starch, were incorporated into the cocoa butter-based FMT to study the effects of these additives with the physical characteristic of a cocoa butter FMT. An optimum-based formulation was chosen according to the desired hardness and disintegration time and the taste masking property achieved with the model drug—dapoxetine. The analysis demonstrated that incorporating beeswax (15%) and paraffin wax (15%) could prolong the disintegration time by at least two-fold. On the contrary, the presence of corn starch was found to cause an increase in the hardness and reduction of the disintegration time. The disintegration mechanism might be presumed due to the synergistic effect of starch swelling and cocoa butter melting. The hardness value and in vitro disintegration time of the optimum formulation were recorded at 2.93 ± 0.22 kg and 151.67 ± 6.98 s. In terms of dissolution, 80% of dapoxetine was released within 30 min and the dissolution profile was comparable to the innovator product. The formulation was palatable and stable for at least 1 year. The exposure of the FMT formulation at 30 °C for 12 months was reported to be stable. Along with the sound palatability profile and high drug load capacity, the current formulation possesses the desired characteristics to be scaled up and marketed.

Underwater passive manoeuvring target tracking with isogradient sound speed profile

Compared with the traditional tracking problem, the underwater 3-D passive manoeuvring target tracking faces the following challenging problems: (1) Since the signal propagation delay is varying and unknown, the relationship between the two adjacent target states is hard to describe; (2) limited by the underwater environment, it is more difficult to establish a target manoeuvring motion model; (3) the propagation speed of the underwater acoustic signal varies with the depth, and the propagation path will be curved instead of straight. Various parameters including signal propagation delay, target pitch angle and receiving frequency measured by the observer cannot be calculated as usual. In this paper, we improved a 3-D constant turn (3D-CT) model to match the underwater target motion. For the problems (1) and (3), this paper proposes a novel interacting multiple model underwater Gauss-Helmert unscented Kalman filter (IMM-UGHUKF) with isogradient sound velocity profile, which analytically describes the relationship between the state to be estimated and the passive measurement. This method augments the unknown signal emission time into the state with implicit equations, and transits the state by the Gauss–Helmert model. Simulation tests have been carried out, and the results show that IMM-UGHUKF can significantly reduce the estimation error compared with other approaches.

Retrieval of sound-velocity profile in ocean by employing Brillouin scattering LiDAR.

Accurate remote sensing of the sound velocity profile of the upper-ocean mixed layers is of major important in oceanography, especially in underwater acoustic communication. However, the existing technologies cannot realize fast and real-time detection on sound velocity profile, a cost efficiency, flexibility, and real-time remote sensing technique is still highly urgent. In this paper, we propose a novel approach based on stimulated Brillouin scattering (SBS) LiDAR for retrieving the sound velocity profile. The sound velocity profiles in the upper-ocean mixed layer of South China Sea were retrieved theoretically and experimentally. We simulated the sound velocity profile of the upper-ocean mixed layer in South China Sea by using the Del Grosso algorithm and the data of temperature, salinity, depth selected from the World Ocean Atlas 2018 (WOA18). We designed a special ocean simulation system to measure the sound velocity in seawater with different temperatures, salinities, and pressures through measuring the frequency shift of SBS. Based on the measured sound velocities, we built a retrieval equation to express the sound velocity as a function of temperature, salinity, and pressure. Then, we retrieved the sound velocity profile of the upper-ocean mixed layer of South China Sea by using the retrieval equation. The results show that the retrieved sound velocity profile is good agreement with the theoretical simulation, and the difference between them is approximately 1∼2 m/s. Also, we have analyzed the differences between the theoretical simulation and experimental measurement. This work is essential to future application for remote sensing the sound velocity distribution profiles of the upper-ocean mixed layers by using the Brillouin LiDAR technique.

Enhancing Engine Order Sound Using Additive Feedforward Control for a Secondary Path with Uncertainty at Higher Frequencies

An active sound profiling (ASP) control algorithm based on the command FxLMS with an additive feedforward enhancement is suggested to overcome the limited performance to track a pre-defined target sound in a car cabin when an electronic sound generator (ESG) attached to a cowl panel of a car was adopted as a secondary actuator. As the uncertainty of the secondary path including the ESG-cowl pair was increased especially at higher frequencies, the tracking performance of a pure ASP algorithm was limited. The feedforward enhancement was added to the pure ASP algorithm to allow a robust tracking performance against a pre-defined target sound to enrich the insufficient engine sound at higher engine orders. After implementing this additive ASP approach in a test car, a real-time control experiment was carried out to demonstrate its tracking performance. A target sound was defined to cancel three engine order noises and to enhance the other three order sounds in the experiment. The experiment results showed that the proposed approach was able to provide an improved robust tracking performance at the engine orders for enhancing sound at higher frequencies compared to the pure ASP algorithm.