Kyle Myers

Systems Thinking Tools as Applied to Community-Based Participatory Research A Case Study

Community-based participatory research (CBPR) is being used increasingly to address health disparities and complex health issues. The authors propose that CBPR can benefit from a systems science framework to represent the complex and dynamic characteristics of a community and identify intervention points and potential “tipping points.” Systems science refers to a field of study that posits a holistic framework that is focused on component parts of a system in the context of relationships with each other and with other systems. Systems thinking tools can assist in intervention planning by allowing all CBPR stakeholders to visualize how community factors are interrelated and by potentially identifying the most salient intervention points. To demonstrate the potential utility of systems science tools in CBPR, the authors show the use of causal loop diagrams by a community coalition engaged in CBPR activities regarding youth drinking reduction and prevention.

Impact of adding artificially generated alert sound to hybrid electric vehicles on their detectability by pedestrians who are blind

A repeated-measures design with block randomization was used for the study, in which 14 adults with visual impairments attempted to detect three different vehicles: a hybrid electric vehicle (HEV) with an artificially generated sound (Vehicle Sound for Pedestrians [VSP]), an HEV without the VSP, and a comparable internal combustion engine (ICE) vehicle. The VSP vehicle (mean +/- standard deviation [SD] = 38.3 +/- 14.8 m) was detected at a significantly farther distance than the HEV (mean +/- SD = 27.5 +/- 11.5 m), t = 4.823, p < 0.001, but no significant difference existed between the VSP and ICE vehicles (mean +/- SD = 34.5 +/- 14.3 m), t = 1.787, p = 0.10. Despite the overall sound level difference between the two test sites (parking lot = 48.7 dBA, roadway = 55.1 dBA), no significant difference in detection distance between the test sites was observed, F(1, 13) = 0.025, p = 0.88. No significant interaction was found between the vehicle type and test site, F(1.31, 16.98) = 0.272, p = 0.67. The findings of the study may help us understand how adding an artificially generated sound to an HEV could affect some of the orientation and mobility tasks performed by blind pedestrians.

Vehicle surge detection and pathway discrimination by pedestrians who are blind: Effect of adding an alert sound to hybrid electric vehicles on performance

This study examined the effect of adding an artificially generated alert sound to a quiet vehicle on its detectability and localizability with 15 visually impaired adults. When starting from a stationary position, the hybrid electric vehicle with an alert sound was significantly more quickly and reliably detected than either the identical vehicle without such added sound or the comparable internal combustion engine vehicle. However, no significant difference was found between the vehicles in respect to how accurately the participants could discriminate the path of a given vehicle (straight vs. right turn). These results suggest that adding an artificial sound to a hybrid electric vehicle may help reduce delay in street crossing initiation by a blind pedestrian, but the benefit of such alert sound may not be obvious in determining whether the vehicle in his near parallel lane proceeds straight through the intersection or turns right in front of him.

Uncovering Spatial Variation in Acoustic Environments Using Sound Mapping.

Animals select and use habitats based on environmental features relevant to their ecology and behavior. For animals that use acoustic communication, the sound environment itself may be a critical feature, yet acoustic characteristics are not commonly measured when describing habitats and as a result, how habitats vary acoustically over space and time is poorly known. Such considerations are timely, given worldwide increases in anthropogenic noise combined with rapidly accumulating evidence that noise hampers the ability of animals to detect and interpret natural sounds. Here, we used microphone arrays to record the sound environment in three terrestrial habitats (forest, prairie, and urban) under ambient conditions and during experimental noise introductions. We mapped sound pressure levels (SPLs) over spatial scales relevant to diverse taxa to explore spatial variation in acoustic habitats and to evaluate the number of microphones needed within arrays to capture this variation under both ambient and noisy conditions. Even at small spatial scales and over relatively short time spans, SPLs varied considerably, especially in forest and urban habitats, suggesting that quantifying and mapping acoustic features could improve habitat descriptions. Subset maps based on input from 4, 8, 12 and 16 microphones differed slightly (< 2 dBA/pixel) from those based on full arrays of 24 microphones under ambient conditions across habitats. Map differences were more pronounced with noise introductions, particularly in forests; maps made from only 4-microphones differed more (> 4 dBA/pixel) from full maps than the remaining subset maps, but maps with input from eight microphones resulted in smaller differences. Thus, acoustic environments varied over small spatial scales and variation could be mapped with input from 4–8 microphones. Mapping sound in different environments will improve understanding of acoustic environments and allow us to explore the influence of spatial variation in sound on animal ecology and behavior.

Blind pedestrians and quieter vehicles: How adding artificial sounds impacts travel decisions

This research examined the influence “quiet” (e.g., hybrid and electric) vehicles may have on the ability of blind pedestrians to perform common orientation and mobility tasks under low vehicle speed conditions. The research involved blind participants detecting forward approaching vehicles and approaching backing vehicles, deciding whether a vehicle coming from behind or from the front but across an intersection would continue to go straight or turn across the intended path of travel of a pedestrian seeking to cross a street (i.e., a pathway discrimination task), and taking parallel and perpendicular alignment from passing traffic. Participants included some with normal hearing and some with impaired hearing.Testing was conducted on a public roadway and a parking lot in Kalamazoo, Michigan under ambient sound conditions consistent with a typical urban travel environment. Conditions involved evaluating internal combustion engine (ICE) Chevrolet Malibu and a set of hybrid Chevrolet Volts capable of operating in a “quiet” mode (referred to as Electric Mode or EM) or operating in EM but augmented with one of five different artificially-generated sounds emanating out of a front-bumper mounted speaker.All of the artificial sounds generally performed better against the baseline the Chevrolet Volt EM than the Chevrolet Malibu. This suggests that, to some extent, putting any one of these artificial sounds on a hybrid or electric vehicle may improve pedestrian performance on the measures examined relative to not adding any sound at all. One sound (sound 5) did not outperform against the Chevrolet Malibu in any measure and had the fewest instances of outperforming the Chevrolet Volt EM. Of the remaining 4 sounds, two sounds outperformed both the Chevrolet Malibu and the Chevrolet Volt EM on several measures. Against the Chevrolet Malibu, sound 2 was slightly better in detection distance and crossing margin while sound 4 was better in the path discrimination tasks. The two sounds were equivalent on the alignment tasks.The pathway discrimination task reflects one of the more potentially threatening situations in which a blind pedestrian might encounter a quiet vehicle (e.g., turning to cross the pedestrian’s path). Sound 4 performed much better than sound 2 on this measure, making it the most effective of all the artificial sounds examined. While these two sounds were equitable in the right-straight task, sound 4 showed almost half as many missed vehicle surges (i.e., forward movement from a stop) and 1/4 the rate of missed paths and incorrect judgments. Vehicle sound condition did not impact participants’ alignment. Normal hearing participants performed significantly better than hearing impaired participants on this task, but not as well as would be expected based on previous data [1].These results support the potential for artificially-generated sounds to improve the ability of blind pedestrians to detect approaching vehicles relative to what is being achieved with ICE vehicles. Regression analysis of the detection data supports previous results that sound energy in the 500 to 1000 Hz range is important for detection. However, the analysis indicates it is not that energy in this region that makes the signal more noticeable, but that energy in this region in the ambient environment hinders detection. Previous findings in low ambient conditions showing a predictive value for the amplitude modulation of an artificial sound were not supported in these data.Copyright

Design of an anechoic termination for automotive applications.

In various automotive applications, the acoustic performance of tuning devices is assessed by measuring the transmission loss (TL) using the decomposition method [as described by Tao and Seybert (2003)]. The decomposition method, which “decomposes” the pressure wave into its incident and transmitted components, assumes an anechoic termination. However, the reliability of measurements using the decomposition method is compromised in the absence of a good anechoic termination. Thus, there is a need to accurately predict the performance of anechoic terminations. This paper constructs a finite element model in ANSYS of a typical anechoic termination consisting of a horn terminating into a pipe filled with absorbing material in order to predict the reflection coefficient across a broad range of frequencies. The model is compared to analytical predictions and experimental measurements of a prototype with similar geometry. This study could lead to further work towards optimization of horn geometry and the bodies...

Design of in-plane functionally graded material plates for improved vibration characteristics

A method for improving the vibration characteristics of plate structures is proposed. This method uses functionally graded material (FGM) instead of isotropic material to construct the plates. The volume fraction of each material constituent is defined in the plane of the plate by a 2D trigonometric law, while the material properties through the thickness are assumed constant. The finite element method is used for modal and harmonic analysis, and a genetic algorithm is utilized for optimization of the chosen objective function. The efficacy of the method is demonstrated by two design problems. In the first design problem, FGM is used to maximize the fundamental frequencies of plates with different boundary conditions. In the second design problem, the kinetic energy of a vibrating FGM plate is minimized at a specific excitation frequency. These example design problems show that material tailoring of plate structures using FGM can result in substantial improvements of their vibration characteristics. The r...

Design of in-plane functionally graded material plates for optimal vibration performance

A method for improving the vibration characteristics of plate structures is proposed. This method uses functionally graded material (FGM) instead of isotropic material in constructing the plates. The distribution of volume fractions of the FGM constituent is defined in the in-plane directions by a trigonometric law. The finite element method is used for the modal and harmonic analysis of plates, and a genetic algorithm is utilized for optimization of the chosen objective function. The efficacy of the method is demonstrated by two design problems. In the first design problem, FGM is used to maximize the fundamental frequencies of plates with different boundary conditions. In the second design problem, the kinetic energy of a vibrating FGM plate is minimized at a specific excitation frequency. These example design problems show that material tailoring of plate structures using FGM can result in substantial improvements of their vibration characteristics. The results can be used to guide the practical design of FGM plates to enhance their dynamic properties.

Wavenumber analysis of vibrating dimpled beams

A structure’s noise and vibration characteristics can be changed by introducing dimples onto the surface. These structural modifications are an attractive form of noise control since they are simple to manufacture and do not add mass to the structure. In order to gain a better understanding of the effect of dimples, beams with different number of dimples are considered in this study. The natural frequencies and mode shapes of beams with any number of dimples are computed using a boundary value model derived from Hamilton’s Principle. The results of this model are compared to the finite element method and to previous literature. Then, the effect of the dimples on the radiation properties of beams is investigated by examination of their wavenumber spectra. By shifting the wavenumber content of the beam between supersonic and subsonic regions, dimples are able to change the amount of radiation emitted. For some boundary conditions, the wavenumber spectrum is time-dependent as the beam vibrates through a comp...

Analysis of the forced response and radiation of a single-dimpled beam with different boundary conditions

Beading and dimpling via the stamping process has been used for decades to stiffen structures (e.g., beams, plates, and shells) against static loads and buckling. Recently, this structural modification technique has been used as a means to shift a structures natural frequencies and to reduce its radiated sound power. Most studies to date have modeled dimpled beams and dimpled/beaded plates using the finite element method. In this research, an analytical model is developed for a beam with any number of dimples using Hamiltons Principle. First, the natural frequencies and mode shapes are predicted for a dimpled beam in free transverse vibration. A comparison with those obtained using the finite element method shows excellent agreement. Second, the forced response of a dimpled beam is calculated for a given input force. Mode shapes properly scaled from the forced response are used in order to calculate the beam strain energy, thus demonstrating the effect of dimpling on beam natural frequencies. Finally, s...