bluuebunny/crossref_metadata_2025 huggingface dataset:
The association between female genital fistula symptoms and gender‐based violence: A multicountry secondary analysis of household survey data
Authors: Mallick Lindsay , Tripathi Vandana
Published: November 2017

Objective

The Demographic and Health Surveys (DHS), which include standardised questions on female genital fistula symptoms, provide a unique opportunity to evaluate the epidemiology of fistula. This study sought to examine associations between self‐reported fistula symptoms and experience of gender‐based violence (GBV) among women interviewed in DHS surveys.

Methods

This study used data from thirteen DHS surveys with standardised fistula and domestic violence modules. Data from the most recent survey in each country were pooled, weighting each survey equally. Multivariable logistic regressions controlled for maternal and demographic factors.

Results

Prevalence of fistula symptoms in this sample of 95 625 women ranges from 0.3% to 1.8% by country. The majority of women reporting fistula symptoms (56%) have ever experienced physical violence, and more than one‐quarter have ever experienced sexual violence (27%), compared with 38% and 13% among women with no symptoms, respectively. Similarly, 16% of women with fistula symptoms report recently experiencing sexual violence—twice the percentage among women not reporting symptoms (8%). Women whose first experience of sexual violence was from a non‐partner have almost four times the odds of reporting fistula symptoms compared with women who never experienced sexual violence. These associations indicate a need to investigate temporal and causal relationships between violence and fistula.

Conclusions

The increased risk of physical and sexual violence among women with fistula symptoms suggests that fistula programmes should incorporate GBV into provider training and services.
Comparison of haematology and biochemistry parameters in healthy South African infants with laboratory reference intervals
Authors: Schmidt B.‐M. , Tameris M. , Geldenhuys H. , Luabeya A. , Bunyasi E. , Hawkridge T. , McClain J. B. , Mahomed H. , Scriba T. J. , McShane H. , Hatherill M.
Published: November 2017

Objective

Paediatric laboratory reference intervals used in Africa and Asia may be derived from historical intervals of predominantly Caucasian infants in Europe or North America. These intervals may therefore not be compatible with the range of normality for developing country populations. We aimed to compare haematology and biochemistry parameters in healthy South African infants with local laboratory reference intervals.

Methods

We compared the baseline haematology and biochemistry results of 634 (316 male and 318 female) HIV‐unexposed infants, aged 3–6 months, living in a rural area of the Western Cape Province, South Africa, against laboratory reference intervals supplied by the South African National Health Laboratory Services (NHLS). We calculated the percentage of observed values out of bound (in terms of lower and upper limits) compared to laboratory reference intervals.

Results

Of the 634 healthy infants screened, 316 (49.84%) were male and 318 (50.16%) female. A majority (91.05%) had platelet counts above the laboratory reference interval upper limit (350 × 109cells/l), while over half, 54.85% and 56.98% had mean corpuscular volume (MCV) and mean corpuscular haemoglobin (MCH) values below the lower limits of 77.0–105.0 fl and 26.0–34.0 pg, respectively. A small proportion were outside the reference limits for haematocrit, namely 15.71% below and 7.14% above the normal limits of 0.31–0.38 l/l. For male and female infants, 33.65% and 18.04% of alkaline phosphatase (ALP) values and 7.01% and 14.56% of alanine transaminase (ALT) values were above the upper limits, respectively. For male infants, 10.83% of gamma‐glutamyl transferase (GGT) values, and for female infants, 31.11% of GGT values were below the lower limits of 12 U/l for males and 15 U/l for females. We observed no significant deviations (>10% out of bound) from NHLS reference intervals in the remaining haematology and biochemistry parameters measured.

Conclusions

Haematology and biochemistry parameters in apparently healthy South African infants deviate frequently from national laboratory reference intervals, including abnormalities consistent with subclinical hypochromic microcytic anaemia. It is important that clinical laboratory reference intervals for children are derived locally, rather than being adopted from Caucasian norms in developed countries, because clinical trials of vaccines, drugs and diagnostics are increasingly conducted in sub‐Saharan Africa.
Acción con daño: del asistencialismo a la construcción social de la víctima. Mirada a procesos de reparación e intervención psicosocial en Colombia
Authors: Villa Gomez Juan David , Barrera Machado Daniela , Arroyave Pizarro Laura , Montoya Betancur Yirley
Published: November 2017

Este artículo, producto de la investigación “Construcción de significados sobre reparación institucional y reparación desde abajo en víctimas del conflicto armado”, desarrollada desde la Universidad San Buenaventura – Medellín, utilizó el método cualitativo, con enfoque fenomenológico-hermenéutico y un muestreo no probabilístico, tipológico e intencional. En el municipio de San Carlos, se realizaron 12 grupos de discusión (SC-GF), 7 entrevistas individuales (SC-EI) y 5 entrevistas grupales (SC-EG). En Medellín desarrollamos 8 grupos de discusión (AM-GF) y 12 entrevistas individuales (AM-EI). Finalmente realizamos 32 entrevistas en profundidad (P-E) a profesionales que manifestaron desgaste intenso en su labor. En todos estos escenarios emergió la categoría “Acción con daño”, evidenciando incoherencias, problemas en proyectos de reparación psicosocial y afectaciones que profundizan el daño.
Emotional Intelligence in Colombian Primary School Children. Location and Gender Analysis
Authors: Herrera Torres Lucía , Buitrago Bonilla Rafael Enrique , Cepero Espinosa Sergio
Published: November 2017

This paper analyses Emotional Intelligence (EI) in Colombian Primary School Children depending on their location (rural or urban) and gender. The final sample consisted of 1451 students in fourth and fifth grade of three provinces in Boyacá department. Emotional Quotient Inventory: Youth Version (EQ-i: YV; Bar-On & Parker, 2000) was used for data collection. Both the reliability and validity of EQ-i: YV have been determined for this sample. The main results revealed differences in EI according to location. Overall, EI was higher in the urban than rural settings. Also, scores on the dimensions interpersonal and adaptability differed by gender. Additionally, the need for future research and development of Social and Emotional Learning programs in schools is discussed.
Revisión del Cuestionario de Emociones Positivas para adolescentes. Propiedades psicométricas de la nueva versión abreviada
Authors: Rodriguez Lucas Marcelo , Oñate María Emilia , Mesurado Belén
Published: November 2017

Las emociones positivas son aquellas experiencias emocionales en las que predomina el placer o bienestar, con una interpretación personal positiva del suceso, trayendo consigo una cascada de cambios subjetivos a nivel fisiológico, psicológico, conductual e incluso social. Las mismas amplían nuestro repertorio de pensamientos y acciones, y potencian la construcción de recursos personales de manera perdurable. El Cuestionario de Emociones Positivas (CEP) para adolescentes mide las emociones de alegría y sentido del humor, optimismo, tranquilidad, gratitud, interés-entusiasmo y satisfacción con la vida. El propósito del estudio fue, en el Estudio 1, evaluar la validez factorial del Cuestionario de Emociones Positivas Cuestionario de Schmidt (2008) y obtener una versión breve del mismo; el propósito del Estudio 2 es probar mediante análisis factorial confirmatorio la estructura factorial de versión breve y evaluar la validez de criterio con el comportamiento prosocial. Los resultados muestran una buena validez factorial para el modelo original de 65 elementos con 6 dimensiones. El modelo de 65 artículos se redujo en una versión abreviada de 31 ítems, obteniendo un buen ajuste del modelo (χ2 / gl = 1.87 CFI = 0.92 GFI = 0.91). En cuanto a la validez de criterio de la versión breve, se encontró que el comportamiento prosocial estuvo asociado con la alegría y el humor (0.34), la gratitud (0.32) y el interés entusiasmo (0.39) dimensiones que componen el Cuestionario de Emociones Positivas. Los resultados se discuten a la luz de las teorías actuales.
Reconciliación Social como estrategia para la transformación de los conflictos socio-políticos, variables asociadas e instrumentos de medición
Authors: Alzate Mónica , Dono Marcos
Published: November 2017

La reconciliación social ha sido propuesta como una de las estrategias que permite la transformación de los conflictos y el restablecimiento de las relaciones intergrupales pacíficas. El objetivo de este trabajo es hacer una revisión sistemática de la reconciliación, las variables con las que se asocia y los instrumentos para medirla. La búsqueda se hizo en Psycinfo y en la Web of Science, los resultados indican que el mayor porcentaje de artículos surge en los años 90, las publicaciones abordan conflictos que se desarrollan a lo largo de todo el planeta: América, Europa, Oriente medio y África. Las variables con las cuales se relaciona estadística y teóricamente a la reconciliación se agrupan en cinco categorias de variables: recuperación psicosocial, acercamiento de las partes confrontadas, resignificación endo y exogrupal, emociones y gestión del conflicto. Se registran 12 instrumentos con una fiabilidad adecuada para evaluar la reconciliación. Se concluye que con las cinco categorías de variables se podrían diseñar modelos explicativos y de diagnóstico que contribuyan a la promoción de los procesos de reconciliación social temprana, particularmente para aquellos paises que requieren transformar las dinámicas de confrontación violenta.
Experimental and Numerical Investigation on Windage Power Losses in High Speed Gears
Authors: Massini Daniele , Fondelli Tommaso , Andreini Antonio , Facchini Bruno , Tarchi Lorenzo , Leonardi F.
Published: November 2017

Enhancing the efficiency of gearing systems is an important topic for the development of future aero-engines with low specific fuel consumption. An evaluation of its structure and performance is mandatory in order to optimize the design as well as maximize its efficiency. Mechanical power losses are usually distinguished into two main categories: load-dependent and load-independent losses. The former are all those associated with the transmission of torque, while the latter are tied to the fluid dynamics of the environment, which surrounds the gears. The relative magnitude of these phenomena is dependent on the operative conditions of the transmission: load-dependent losses are predominant at slow speeds and high torque conditions, load-independent mechanisms become prevailing in high speed applications, like in turbomachinery. A new test rig was designed for investigating windage power losses resulting by a single spur gear rotating in a free oil environment. The test rig allows the gear to rotate at high speed within a box where pressure and temperature conditions can be set and monitored. An electric spindle, which drives the system, is connected to the gear through a high accuracy torque meter, equipped with a speedometer providing the rotating velocity. The test box is fitted with optical accesses in order to perform particle image velocimetry (PIV) measurements for investigating the flow field surrounding the rotating gear. The experiment has been computationally replicated, performing Reynolds-averaged Navier–Stokes (RANS) simulations in the context of conventional eddy viscosity models, achieving good agreement for all of the speed of rotations.
Static Load Performance of a Water-Lubricated Hydrostatic Thrust Bearing
Authors: Rohmer Michael , San Andrés Luis , Wilkinson Scott
Published: November 2017

In rotating equipment, thrust bearings aid to balance axial loads and control shaft position. In turbomachinery, axial loads depend on shaft speed and pressure rise/drop on the impellers. This paper details a water-lubricated test rig for measurement of the performance of hydrostatic thrust bearings (HTBs). The rig contains two water-lubricated HTBs (105 mm outer diameter (OD)), one is the test bearing and the other a slave bearing. Both bearings face the outer side of thrust collars of a rotor. The paper shows measurements of HTB axial clearance, flow rate, and recess pressure for operation with increasing static load (max. 1.4 bar) and supply pressure (max. 4.14 bar) at a rotor speed of 3 krpm (12 m/s OD speed). Severe angular misalignment, static and dynamic, of the bearing surface against its collar persisted and affected all measurements. The HTB axial clearance increases as the supply pressure increases and decreases quickly as the applied load increases. The reduction in clearance increases the flow resistance across the film lands, thus reducing the through flow rate with an increase in recess pressure. In addition, an estimated bearing axial stiffness increases as the operating clearance decreases and as the supply pressure increases. Predictions from a bulk flow model qualitatively agree with the measurements. Alas they are not accurate enough. The differences likely stem from the inordinate tilts (static and dynamic) as well as the flow condition. The test HTB operates in a flow regime that spans from laminar to incipient turbulent. Quantification of misalignment at all operating conditions is presently a routine practice during operation of the test rig.
Using reciprocity to derive the far field displacements due to buried sources and scatterers
Authors: Rose L. R. Francis , Chiu W. K. , Nadarajah N. , Vien B. S.
Published: November 2017

It is shown that elastodynamic reciprocity provides a simpler approach for deriving the far-field displacements due to buried (sub-surface) sources in a half-space, compared with integral transform techniques. The auxiliary fields employed in this approach are the fields associated with the reflection of plane waves of the three possible polarisations, and the required far field can be expressed in terms of these well-known auxiliary fields. The crucial step in this approach is to evaluate a surface integral involving cross-work terms between an outgoing spherical wavefront and the auxiliary fields consisting of incident and reflected plane waves. This integral can be evaluated by the stationary phase approximation for the two-dimensional case, or by a generalisation of this approximation for the three-dimensional case. Although this evaluation involves several distinct contributions, the final result is shown to be very simple, and it can be interpreted as a generalisation of a known result for the one-dimensional case, whereby the net contribution arises only from counter-propagating waves of the same mode. The results derived for a buried force are extended to the case of buried cracks by exploiting the body force equivalents for displacement discontinuities across a surface.
Challenges of entertainment sound in communities
Authors: Siebein Gary W. , Siebein Gary , Paek Hyun , Roa Marylin , Miller Jennifer R. , Siebein Keely
Published: November 2017

There are three basic challenges of entertainment sound in communities. First is how to measure the sound. People often clearly hear individual notes of music being played, individual beats from drums, and other lower frequency percussive instruments and sounds of words sung by performers at locations away from the facility. Equivalent sound levels taken over varying periods of time, LA Fast, LA slow, and other experimental metrics will be compared with the audibility of the sounds by people at remote listening locations. Second, it is often necessary to correct the measurements for the effects of background noise when equivalent sound levels are measured because the short term transient sounds that contain the musical information have been “averaged away” and the resulting sound levels are in the vicinity of the background sounds even though the words and music are plainly audible. Third is that methods to effectively contain the sounds from outdoor amplified entertainment facilities including operational controls, infrastructure controls, and administrative controls should be considered. All three challenges must be addressed to optimize the compatibility of the facility with the community.
Interpreting conflicting noise ordinances imposed upon Merriweather Post Pavilion
Authors: Curley Josh , Harvey Scott
Published: November 2017

Merriweather Post Pavilion in Columbia, Maryland, has been host to numerous concerts and music festivals each year since it opened in 1967. Over the years, noise complaints regarding Merriweather have not been uncommon during musical acts. In 2013, a noise ordinance was placed on the venue that allows concert events to generate a noise level up to 95 dBA at a ¼-mile radius from the main stage between the hours of 9:00 AM and 11:00 PM, and 72.5 dBA at residential property lines. Between 11:00 PM and 11:30 PM, main stage noise levels must not exceed 55 dBA as measured both within the ¼-mile radius and at residential property lines. Currently, the residence closest to the main stage is approximately 1,400 feet away, just outside of the ¼-mile 95 dBA allowance; however, residential construction is planned in the next few years as close as 750 feet behind the main stage. Once these residential buildings are occupied, how will the noise ordinance be applied if main stage noise is greater than the 72.5 dBA allowance at residential buildings yet below the 95 dBA limit within the ¼-mile radius? And, how will the likely complaints regarding audible low frequency noise inside the residences, which are not addressed by the noise ordinance, be handled?
Typical outdoor audio system designs
Authors: Miller Andrew N.
Published: November 2017

Trends in audio system designs for outdoor entertainment venues impact the sound in surrounding communities. The author explores typical audio system designs for outdoor amplified music venues and high school football stadiums in and around Austin, Texas. The consequences of particular system designs will be discussed as they relate to sound in surrounding communities. Given special consideration are characteristics of sound at the property line of venues employing loudspeaker array and point-source systems.
Benefits of managing source sound levels in amplified indoor entertainment venues
Authors: Woolworth David S.
Published: November 2017

This paper investigates sound levels on stage and in the audience from field measurements and the literature for small and midsize amplified venues for various entertainment types. The effect of sound levels are also briefly examined in regard to hearing and comfort of patrons and employees. Furthermore, reduction in sound level internally is examined as a community noise control measure relative to soundproofing.
Entertainment sounds, the soundscape, and resources
Authors: Schulte-Fortkamp Brigitte
Published: November 2017

Assessing the impact of entertainment sounds in communities will need a multifaceted analysis. An evaluation process has to be considered that will cover the different facets with regard to people’s understanding about an acoustic environment where the impact of entertainment sound will occur. The “meeting of music and environment” discussed by R. M. Schafer opens the mind in many directions to learn about the different aspects and related impacts in such a soundscape that is relying on given activities in an area that will lead to a harmonized or an acoustically unbalanced situation. Understanding human auditory scene analysis and the important role of auditory attention forces to outline soundscape assessment methods and to come to enhanced methodologies for inventing action parameters with regard to a sounding community. This paper will introduce regulations to harmonize the different interests regarding interventions through entertainment sounds in communities but also introduce the soundscape approach to offer new features with regard to a balanced and harmonic soundscape addressing entertainment sounds as a resource.
Case study of an outdoor music festival in a rural community
Authors: Lilkendey Robert M.
Published: November 2017

A case study will be presented of the author’s involvement in assisting Okeechobee County, Florida, with the development of acoustical criteria and monitoring of live music events associated with a four-day outdoor music festival that takes place annually in a rural part of the county. The presentation will include the results of these efforts, as well as a discussion of the collaborative process that continues to take place between the promoter, promoter’s acoustical consultant, the county planning and zoning department, residents, elected county officials, law enforcement, and the author to work toward a solution for future festivals that balances the monetary benefits for the entire county with the needs of the relatively small percentage of county residents adversely affected by the noise.
Tidal influence on underwater soundscape characteristics in a shallow-water environment off Taiwan
Authors: Guan Shane , Chen Chi-Fang , Wu Chih-Hao , Liu Dai-Hua , Vignola Joseph F.
Published: November 2017

Passive acoustic monitoring has been conducted in shallow-water environment off the coast of west Taiwan using bottom-mounted hydrophones to obtain baseline soundscape information prior to large scale wind farm constructions. Analyses of long-term acoustic datasets were conducted in three distinctive one-octave bands: 150-300 Hz, 1,200-2,400 Hz, and 3,000-6,000 Hz. Initial study was able to link the 150-300 Hz band to passages of cargo vessels. However, further research using time-frequency analysis showed an approximate 6-hour cycle of strong occurrence of this noise band, which corresponds particularly well with the local semidiurnal tidal cycle. The results suggest that at least part of the high noise levels between the high- and low-water periods in the 150-300 Hz octave band was due to flow noise from tidal movements. The results underlines the importance to consider oceanographic processes such as tidal and wave movements when studying the contribution of specific acoustic sources to the underwater soundscape.
Long-term measurements of the ice-free underwater noise field directionality in the shallow Beaufort Sea
Authors: Thode Aaron , Blackwell Susanna B. , Conrad Alexander , Kim Katherine H.
Published: November 2017

Between 2007 and 2014, over 35 Directional Autonomous Seafloor Acoustic Recorders (DASARs) were deployed over a 280 km swath of the Beaufort Sea continental shelf (20-55 m depth) during the open-water season, in order to monitor the westward bowhead whale migration. DASARs have one omnidirectional pressure sensor and two orthogonal particle velocity sensors that permit instantaneous measurement of the azimuths of both transient signals and continuous noise between 20 and 500 Hz, including diffuse wind-driven ocean noise. The lack of significant shipping or industrial noise in this region provides a rare opportunity to directly measure the properties of wind-driven noise in expanding ice-free regions. Here, we map the azimuthal directionality of the diffuse Beaufort ambient noise field as a function of frequency and location across all seven seasons. The dominant directionality of the diffuse ambient noise field varies strongly with frequency and is highly correlated with the received power spectral density. Certain directional features of the ambient noise field remained stable over seven deployment seasons, suggesting that judicious processing of the ambient noise soundscape could provide underwater navigational information in arctic waters. [Work sponsored by ONR.]
Experimental studies of ice cracking tests in an anechoic chamber
Authors: Ahlrichs Matthew V. , Zhao Chenhui , Prasad Marehalli , Matthews James , Opet Steven , Lyon James , Hinds Trevor , Rogers Khiana
Published: November 2017

As the Northwest passage becomes more frequently traveled by commercial and business interests, it is becoming important to increase existing methods for safety at sea in harsh Arctic conditions. In order to identify ice-floe movements in the Arctic, acoustical signatures for ice behaviors need to be identified and analyzed. Being able to identify the acoustic signature of ice cracking in real-time will help vessels navigate the arctic by identifying moving ice-floes and monitoring present ice conditions. This study identifies a novel method for detecting thermal cracking in ice, ice fracturing, and ice shearing events in an anechoic chamber. Comparing the power spectra and identified peak frequencies against empirically collected data from previous studies, this methodology aims to recreate the arctic environment in a lab without travel to the region for baseline data collection. Furthermore, based on a literature review, little power spectra data exist. The data collected from this study will add to the creation of a baseline identification for future ice fracture studies. Observations are made on the collected data which can be used to improve navigational methods for safety at sea.
Partitioning wind and ship generated sound using vertical noise coherence
Authors: Shajahan Najeem , Barclay David R.
Published: November 2017

Continuous ambient noise data were recorded during April and May 2016, using a four-element vertical array deployed near the continental shelf break south of Martha’s Vineyard. A technique for classifying and partitioning ambient noise using the vertical noise coherence function is proposed. Time series analysis of the noise power spectrum reveals the presence wind, distant shipping, and near-field individual ship noise in the region. The noise coherence (directionality) due to wind, distant shipping, and individual ships is analytically modeled using environmental inputs such as the time varying sound speed profile and sediment properties from the measurement site, and compared with the observation. The impact of noise due to ship traffic in the region is estimated by subtracting the best-fit theoretical coherence for wind-generated noise from the measurement. Since the wind generated vertical coherence is stable and independent of source spectrum level, it can be used to quantify the relative contributions of distant shipping and wind noise to the marine environment. Additionally, the time varying vertical coherence from near-field individual ships can be used for estimating their range and speed. [Research supported by ONR.]
Progress toward acoustic volume attenuation tomography
Authors: Verlinden Christopher M. , Tippmann Jeffery D. , Kuperman William A. , Hodgkiss William S.
Published: November 2017

Experiments were carried out in the eastern Pacific and north Atlantic Oceans with the purpose of estimating volume attenuation coefficients in seawater by measuring acoustic amplitude along eigenray paths in the mid-frequency regime (3-9 kHz). A quantitative comparison of the measured attenuation coefficients in three experiment sites is presented here along with a comprehensive examination of historical measurements in these areas. The ability to make precise measurements of acoustic volume attenuation coefficients has applications in detection theory, acoustic communications, and ocean sensing. A method of inverting for properties such as temperature, salinity, and pH, which influence the attenuation of sound in seawater, is discussed.
Three-dimensional noise modeling
Authors: Barclay David R. , Lin Ying-Tsong
Published: November 2017

The ambient sound field due to wind generated surface noise and distant ship generated noise may be highly axially non-symmetric in regions with rapidly changing bathymetry. Some of this asymmetry is due to bathymetric shadowing, while in other cases horizontal refraction contributes significantly. These propagation effects can alter the omnidirectional power spectral levels, as well as the horizontal and vertical noise coherence (directionality). The special case of an idealized Gaussian submarine canyon can be described using the method of normal mode decomposition applied to a three-dimensional longitudinally invariant wave-guide. The modal decomposition is carried out in the vertical and across-canyon horizontal directions and gives a semi-analytical solution describing the three-dimensional bathymetric effects on the noise field. Reciprocal three-dimensional cylindrical co-ordinates parabolic equation (PE) and Nx2D PE sound propagation models can be used to compute the noise field in arbitrary domains. Inter-comparison of these models highlights the effect of the three-dimensional topography on the vertical coherence and mean-noise level as a function of arrival direction relative to the canyon’s axis. These effects include the focusing of noise along the canyon axis and the frequency perturbation of vertical coherence minima. [Research supported by ONR.]
Legendre polynomial method for linear array beam pattern synthesis
Authors: Huang Dehua
Published: November 2017

The detailed design tools for acoustic array sidelobe suppression and beamwidth control by Legendre polynomials technique for equally spaced point source linear acoustic array synthesis are studied and introduced. The method is compared with results obtained by conventional classical Dolph-Chebyshev synthesis technique. Numerical examples were demonstrated by a group of Legendre polynomials of different degrees of N with z0 controlling parameters. Fourier series cosine expansion is applied to calculate element weight coefficient for great advantage when the number of sensor count in an array goes large. Naturally taped sidelobe levels within a beam pattern, and better beam efficiency, a measure of the energy percentage to the mainlobe, were both obtained by Legendre polynomial array synthesis method.
Acoustic beam pattern for a fringe free laser interferometric sound sensor
Authors: McBeth Michael S.
Published: November 2017

A fringe free laser interferometric sound sensor uses parallel, non-intersecting, modulated laser beams in a sound-filled fluid. Therefore, no interference fringes are produced or required in the fluid. Light from each laser beam is collected and combined in an envelope detector where the sound pressure signal appears as angle modulated sidebands. Since the laser beams do not intersect in the sound-filled fluid, we can use a beam separation distance that maximizes the optical path difference between the laser beams to increase sound detection sensitivity. We derive an equation that relates the optical path difference between a pair of laser beams and the peak change in the index of refraction of the fluid due a sound wave. We derive a three dimensional beam pattern and function for this sensor and compare it to that of a conventional line array.
Acoustic field approximation with sparse arrays through optimization
Authors: Miller Lane P. , Thompson Stephen C. , Dittberner Andrew
Published: November 2017

In a previous work, the objective of approximating the acoustic field from an arbitrary continuous aperture with constrained sparse transducer arrays was established. Results from this showed limited accuracy due to the constraints and called for further consideration. The aim of this research is to extend the analysis and increase the accuracy of the field approximation through multi-variable optimization. System parameters such as transducer excitation level and location within the aperture space are varied. The acoustic coupling between transducers is also taken into account. Results from the optimizations will provide the system parameters that minimize error between compared radiation patterns.
Guidelines and principles for noise and vibration performance in an autonomous vehicle
Authors: Mahapatra Arun
Published: November 2017

The field of autonomous vehicles (AVs) has grown substantially in recent years, both in public interest and engineering efforts. This presents a unique challenge in the world of automotive engineering—many processes and principles are based on the presence of an engaged driver or operator, while a passenger in an AV is assumed to have a much lower level of engagement. Additionally, AVs are an entirely new, quickly evolving market that has no historical data to use as a basis for engineering decisions, including those related to the noise, vibration, and harshness (NVH) experienced by a passenger. This paper reviews previous studies focusing on the NVH experiences of automobiles, other forms of transportation (trains, planes), and recent psychoacoustic findings to generate a set of principles and guidelines for NVH development of an AV. While there is minimal real-world information available on a consumer’s experience with an AV, a remarkable amount of information from other industries and environments can be applied to ensure an optimal NVH environment for a passenger of a self-driving vehicle.
Toward acoustic particle velocity sensors in air using entrained balloons: Measurements and modeling
Authors: Williams Randall , Kim Donghwan , Gleason Kristofer L. , Hall Neal A.
Published: November 2017

Acoustic particle velocity sensors for underwater applications typically work by measuring the motion of a small, neutrally buoyant body entrained in the acoustic field. Motivated by this, we have investigated the use of balloons for acoustic particle velocity measurements in air by exploring the behavior of an elastic balloon vibrating in response to an incident acoustic wave. In this presentation, we will present the results of experiments performed in an anechoic chamber, in which a pair of laser Doppler vibrometers simultaneously captured the velocities of the front and back surfaces of a Mylar balloon in an acoustic field. From phase measurements, the motion is described in terms of contributions from odd-order vibration modes (including bulk translation) and even-order vibration modes. The measured entrainment factors for the balloon at low frequencies are seen to be in good agreement with a physical model based on the scattering from an entrained, rigid sphere. This demonstrates the feasibility of using balloons for direct measurement of acoustic particle velocity in air.
An experimental investigation of the nonlinear acoustic response of acoustic sense-ports
Authors: Teasley Thomas W. , Scarborough David
Published: November 2017

Combustion instabilities continue to hinder the development of rocket engines and high-efficiency, low NOx combustion technology used in gas turbine engines. Experimental pressure measurements remain the best method to assess combustion instabilities. However, the harsh, high-temperature environment requires remotely mounting pressure sensors using sense-ports, which cause large discrepancies in measured thrust chamber acoustic pressure amplitudes. For this study, a multi-microphone impedance tube was used to investigate the nonlinear response of an acoustic sense-port. Measurements were performed for frequencies and driving amplitudes ranging from 100 Hz to 1500 Hz and 120 dB to 175 dB, respectively. Measurements were made using four different sense-port area-contraction ratios and for different extension tube lengths. The sense-port and extension tube acoustic responses were measured separately to enable the determination of the abrupt area contraction acoustic response. Measured sense-port area contraction length corrections were found to be in close agreement with the literature. The rigidly terminated sense-port extension tube exhibited linear acoustic damping. Measurements of the abrupt area contraction acoustic response revealed highly nonlinear damping even at low acoustic pressure amplitudes due to flow separation at the abrupt area contraction caused by the local acoustic velocity.
On the acoustic near field of a solid propellant rocket
Authors: Tam Christopher
Published: November 2017

Recently, Horne et al. presented NASA Ames measurements of the acoustic near field of a solid propellant rocket. The experiment consists of two phases: the high-burn and the low-burn phase. The main objective of this investigation is to use this set of data for the determination of the dominant components of near field rocket noise. The data consist of spectral measurements of an array of 14 near field microphones and a single far field microphone. By itself, the data are insufficient to accomplish the stated objective. We supplement the data with information provided by the two-noise source model of hot supersonic laboratory jets. The two-noise source model is supported by the existence of two similarity spectra. By applying the similarity spectra to the data of Horne et al. at low-burn, we are able to show that the dominant components of near field solid propellant rocket noise are the same as those found in the far field of supersonic jets. Further, the data allow the development of a model for the spatial distribution of the dominant noise components. On applying the model to the high-burn phase of the experiment, excellent agreements are found.
Experimental study of the aeroacoustic interaction between two supersonic hot jets
Authors: Lambaré Hadrien
Published: November 2017

The first stage of space launchers often use multiple engines. The supersonic jet noise at lift-off is a major source of vibrations for the launcher’s equipments and payloads. In parallel with the development of the Ariane 6 launcher and its launch pad ELA4, the CNES MARTEL test bench have been improved in order to study experimentally the aeroacoustic interaction between two hot supersonic jets (mach 3, 2000K). In collaboration with the PPRIME laboratory of the University of Poitiers, acoustic and PIV measurements have been made in the free jets configurations. Further test campaigns will study the interaction of jets inside the flame duct, and their impingement on the launch table.
Experimental study of plate-angle effects on acoustic phenomena from a supersonic jet impinging on an inclined flat plate
Authors: Akamine Masahito , Okamoto Koji , Teramoto Susumu , Tsutsumi Seiji
Published: November 2017

Acoustic waves from a rocket exhaust jet cause the intense acoustic loading. Because the exhaust jet impinges on a flame deflector at liftoff of a launch vehicle, an adequate understanding of the acoustic phenomena from a supersonic impinging jet is required for prediction and reduction of the level of the acoustic loading. The previous numerical studies on a supersonic jet impinging on an inclined flat plate [e.g., Tsutsumi et al. AIAA 2014-0882; Nonomura et al. AIAA J. 54(3), 816-827 (2016)] suggested that the plate angle has a large impact on the characteristics of the acoustic waves from the impingement region. In the present study, experiments were carried out to discuss the effect of the plate angle on this acoustic phenomenon. By applying the acoustic-triggered conditional sampling to the schlieren visualization movies, which was proposed by the authors [AIAA 2016-2930], the phenomena around the impingement region were observed in detail. The results revealed that the plate-angle variation leads to the change in the characteristics of the acoustic waves from the impingement region, such as the source locations.
Large eddy simulations of launcher lift-off noise and comparisons to experiments on model flame trenches
Authors: Troyes Julien , Vuillot Francois , Langenais Adrien , Lambaré Hadrien , Noir Pascal
Published: November 2017

During the lift-off phase of a space launcher, rocket motors generate harsh acoustic environment that is a concern for the payload and surrounding structures. Hot supersonic jets contribute to the emitted noise from both their own noise production mechanisms and their interactions with launch pad components, such as the launch table and flame trenches. The present work describes the results of computations performed by ONERA to predict the lift-off noise from reduced scale models of a flame trench. The results include both unsteady flow solution inside the flame trench and the computed noise on near and far field microphone arrays. Numerical computations involve two in-house codes: the flow solver CEDRE, used in LES mode to accurately predict the noise sources, and the acoustic code KIM to reconstruct the far field noise, thanks to an integral Ffowcs Williams and Hawkings porous surface approach. The computational model exactly reproduces the flame trench configurations used in a test campaign carried out by CNES at the MARTEL facility. Results are discussed and compared with experimental acoustic measurements on 48 microphones. Overall, the numerical results reproduce the acoustic measurements within 3 dB. To further improve these results, work is ongoing on acoustic nonlinear effects.
Refinements in RANS-based noise prediction methodology for complex high-speed jets
Authors: Papamoschou Dimitri , Adam Andres
Published: November 2017

Recent efforts on RANS-based modeling of the noise reduction from multi-stream, high-speed jets have underscored the importance of flow properties on the outer surface of peak Reynolds stress (OSPS). In a time-averaged sense, the OSPS is expected to represent the locus of the most energetic eddies in contact with the ambient fluid. The acoustic Mach number on the OSPS is a proxy for the convective Mach number of those eddies, thus has strong impact on the modeling of the noise source and its suppression when the jet plume is distorted into an asymmetric shape. Therefore, accurate detection of the OSPS is a critical ingredient in the modeling. This is complicated by the fact that, in asymmetric jets, the Reynolds stress distribution can be highly irregular and detection of its maximum along a radial line can become problematic. The talk will present advanced algorithms for the detection of the OSPS and resulting improvements in the prediction of noise reduction.
Jet noise prediction via coupling large eddy simulation and stochastic modeling
Authors: Blake Joshua D. , SASSANIS VASILEIOS , Thompson David , Sescu Adrian , Hattori Yuji
Published: November 2017

A novel method for efficient and accurate jet noise prediction is developed and tested in the framework of coupled LES and stochastic noise modeling. In the proposed method, the low frequency range of the acoustic spectrum, which corresponds to large turbulent structures, is resolved with an implicit LES model by employing higher-order spatial and temporal discretizations. The high frequency range, which corresponds to the fine-scale turbulence, is modeled via a stochastic broadband noise generation model. The inputs to the stochastic model are represented by statistics from an axisymmetric RANS jet simulation. The smaller synthetic scales are convected by larger scales, accounting for the effects of sweeping from the larger LES-resolved turbulent scales. The farfield acoustic data is obtained using either the Linearized Euler Equations, or an acoustic analogy based on the Ffowcs-Williams Hawkings method. The method is evaluated on cold and heated jets at different Reynolds numbers.
Validation of a hybrid nonlinear approach for jet noise prediction and characterization
Authors: Sassanis Vasileios , Blake Joshua , Sescu Adrian , Collins Eric M. , Harris Robert E. , Luke Edward A.
Published: November 2017

In this study, a hybrid approach for non-linear jet noise predictions in complex environments is presented and validated. The method differs from traditional approaches in that interactions of the jet with the surrounding structures as well as non-linear disturbances propagating over large distances are taken into consideration in order to quantify their effects on sound generation and propagation. The noise sources founded in the jet plume and the near-field are first computed using the full Navier-Stokes equations. The variables of interest are then interpolated into a second domain. After penalized, they are used as source terms in the non-linear Euler equations to calculate the sound propagation. The interpolation and penalization steps are performed using a buffer region designed by the principles of sponge layers. The effective one-way communication between the two domains and the capabilities of the buffer region to transfer the data from the NS to the Euler domain without any loss of detail is demonstrated. Results from two- and three-dimensional jets both in free space and interacting with solid obstacles are presented. Comparisons with DNC and experimental data in terms of sound pressure level spectra are in good agreement with the ones calculated by our method.
Acoustical Society of America Standards in Mechanical Shock and Vibration
Authors: Gaumond Charles F. , Stremmel Neil B.
Published: November 2017

The Acoustical Society of America maintains standards in several areas. We present the areas covered by ANSI/ASA S2: mechanical shock and vibration and ISO TC 108: mechanical shock, vibration, and condition monitoring. A brief description of each standard is given, with the overlap between ANSI and ISO standards. The work in each area is handled by committees and working groups that represent a diversity of opinions, which is crucial to creating a standard based on consensus of all interested parties. We also present the requirements for official participation in standards, that includes the rights to propose new standards, review and modify old standards, and vote. We present the reasonable fee structures for various types of organizations. Contact information for each committee and working group as well as the location of the information on the ASA Standards website are presented.
Considerations for the evaluation of impact sound from heavy impact sources in adjacent spaces
Authors: Eaton William C. , Stewart Noral D.
Published: November 2017

The ability to limit a sound heard by a neighboring tenant in a mixed-use facility can be achieved by understanding how to control the source of the sound or affect its path. It is also important to evaluate or measure the sound in a way that considers what a tenant might hear. These aspects will be considered when studying impact sound resulting from the drop of heavy impact sources in adjacent spaces.
Method for evaluating and predicting noise from hard, heavy impact sources
Authors: LoVerde John , Dong David W. , Silva Richard , Bevilacqua Antonella
Published: November 2017

Noise and vibration from activity in fitness facilities, in particular, drops of hard heavy weights, is a common source of disturbance and complaint in residential, commercial, and mixed-use building types. Mitigating systems exist, including specially designed rubber flooring tiles and products for architectural vibration isolation systems, but in the United States, there is no standardized method for evaluating the reduction in noise or vibration provided by these products and systems. Quantitative and comparable data of the effectiveness of these products are therefore lacking. The authors previously reported (Internoise 2015, Noise-Con 2016, ASA Boston 2017) a preliminary test method to evaluate athletic tile flooring with heavy weight drops, based on the reduction in floor vibration (delta-LV) achieved due to the insertion of the products. Preliminary results indicated that the delta-LV measurement adequately described the impact reduction due to athletic tile, over a certain frequency range, reasonably independent of structure. This paper continues the research and further refines the measurement method, verifies its use for designing fitness facilities, and examines additional parameters that may affect measuring and evaluating hard, heavy weight impacts.