Experimental validation study of an analytical model of discrete frequency sound propagation in closed-test-section wind tunnels

The principal objective is to assess the adequacy of linear acoustic theory with an impedence wall boundary condition to model the detailed sound field of an acoustic source in a duct. Measurements and calculations are compared of a simple acoustic source in a rectangular concrete duct lined with foam on the walls and anechoic end terminations. Measurement of acoustic pressure for twelve wave numbers provides variation in frequency and absorption characteristics of the duct walls. Close to the source, where the interference of wall reflections is minimal, correlation is very good. Away from the source, correlation degrades, especially for the lower frequencies. Sensitivity studies show little effect on the predicted results for changes in impedance boundary condition values, source location, measurement location, temperature, and source model for variations spanning the expected measurement error

Design and Development of a Deep Acoustic Lining for the 40-by 80-Foot Wind Tunnel Test Section

The work described in this report has made effective use of design teams to build a state-of-the-art anechoic wind-tunnel facility. Many potential design solutions were evaluated using engineering analysis, and computational tools. Design alternatives were then evaluated using specially developed testing techniques, Large-scale coupon testing was then performed to develop confidence that the preferred design would meet the acoustic, aerodynamic, and structural objectives of the project. Finally, designs were frozen and the final product was installed in the wind tunnel. The result of this technically ambitious project has been the creation of a unique acoustic wind tunnel. Its large test section (39 ft x 79 ft x SO ft), potentially near-anechoic environment, and medium subsonic speed capability (M = 0.45) will support a full range of aeroacoustic testing-from rotorcraft and other vertical takeoff and landing aircraft to the take-off/landing configurations of both subsonic and supersonic transports

Factors underlying metastatic breast cancer patients' perceptions of symptom importance: a qualitative analysis

The symptom literature in cancer has primarily examined symptom severity, frequency and distress. Assessing cancer patients' perceptions of symptom importance-how important it is for them to see improvement in a symptom following an intervention-and factors influencing these judgments would also inform patient-centred care, but this analysis has not been undertaken. This qualitative study aimed to identify factors underlying perceptions of symptom importance among 25 symptomatic metastatic breast cancer (MBC) patients. Participants were recruited from a cancer centre in the Midwestern USA. Semi-structured interviews focused on patients' rationale for considering common symptoms (i.e., anxiety, sadness, sleep problems, pain or fatigue) to be important. Thematic analyses revealed five interrelated factors underlying MBC patients' perceptions of symptom importance: activity restriction, concentration difficulties, exacerbation of other physical symptoms, symptom-related long-term health concerns and negative impact on their relationships with others. Patients most frequently stated that a physical or psychological symptom was important because of the resulting activity restriction. Additionally, some patients considered pain to be important because it signalled potential long-term health concerns, such as worsening metastatic disease. Findings suggest that clinicians should take into account MBC patients' perceptions of symptom importance and factors underlying these judgments when making shared treatment decisions

Symptom experiences in metastatic breast cancer patients: relationships to activity engagement, value-based living, and psychological inflexibility

OBJECTIVE: This study examined symptom-based subgroups of metastatic breast cancer (MBC) patients and the extent to which they differed across key constructs of acceptance and commitment therapy (ACT). METHODS: Eighty women with MBC completed self-report surveys assessing 10 common symptoms and several ACT variables (ie, activity engagement, psychological inflexibility, value obstruction, and value progress) during a single time point. RESULTS: A cluster analysis yielded 3 patient subgroups: low symptoms, low-moderate symptoms, and moderate-high symptoms. Relative to the subgroup with low symptoms, the other subgroups reported less activity engagement. In addition, compared with patients with low symptoms, the subgroup with moderate-high symptoms reported greater psychological inflexibility (ie, avoidance of unwanted internal experiences) and greater difficulty living consistently with their values. CONCLUSIONS: Women with MBC show heterogeneity in their symptom profiles, and those with higher symptom burden are more likely to disengage from valued activities and avoid unwanted experiences (eg, thoughts, feelings, and bodily sensations). Findings are largely consistent with the ACT model and provide strong justification for testing ACT to address symptom interference in MBC patients

Metastatic breast cancer patients' expectations and priorities for symptom improvement

PURPOSE: Little research has examined cancer patients' expectations, goals, and priorities for symptom improvement. Thus, we examined these outcomes in metastatic breast cancer patients to provide patients' perspectives on clinically meaningful symptom improvement and priorities for symptom management. METHODS: Eighty women with metastatic breast cancer participated in a survey with measures of comorbidity, functional status, engagement in roles and activities, distress, quality of life, and the modified Patient-Centered Outcomes Questionnaire that focused on 10 common symptoms in cancer patients. RESULTS: On average, patients reported low to moderate severity across the 10 symptoms and expected symptom treatment to be successful. Patients indicated that a 49% reduction in fatigue, 48% reduction in thinking problems, and 43% reduction in sleep problems would represent successful symptom treatment. Cluster analysis based on ratings of the importance of symptom improvement yielded three clusters of patients: (1) those who rated thinking problems, sleep problems, and fatigue as highly important, (2) those who rated pain as moderately important, and (3) those who rated all symptoms as highly important. The first patient cluster differed from other subgroups in severity of thinking problems and education. CONCLUSIONS: Metastatic breast cancer patients report differing symptom treatment priorities and criteria for treatment success across symptoms. Considering cancer patients' perspectives on clinically meaningful symptom improvement and priorities for symptom management will ensure that treatment is consistent with their values and goals

Analysis of In-Flight Vibration Measurements from Helicopter Transmissions

In-flight vibration measurements from the transmission of an OH-58C KIOWA are analyzed. In order to understand the effect of normal flight variation on signal shape, the first gear mesh components of the planetary gear system and bevel gear are studied in detail. Systematic patterns occur in the amplitude and phase of these signal components with implications for making time synchronous averages and interpreting gear metrics in flight. The phase of the signal component increases as the torque increases; limits on the torque range included in a time synchronous average may now be selected to correspond to phase change limits on the underlying signal. For some sensors and components, an increase in phase variation and/or abrupt change in the slope of the phase dependence on torque are observed in regions of very low amplitude of the signal component. A physical mechanism for this deviation is postulated. Time synchronous averages should not be constructed in torque regions with wide phase variation