POPULATION-BASED QUESTIONNAIRE SURVEY ON HEALTH EFFECTS OF AIRCRAFT NOISE ON RESIDENTS LIVING AROUND U.S. AIRFIELDS IN THE RYUKYUS—PART I: AN ANALYSIS OF 12 SCALE SCORES

A questionnaire survey was made of health effects of aircraft noise on residents living around Kadena and Futenma airfields using the Todai Health Index. Aircraft noise exposure expressed by L_dnranged from under 55 to over 70 in the surveyed area. The number of valid answers was 7095, including 848 among the control group. Twelve scale scores were converted to dichotomous variables based on scale scores of the 90 percentile value or the 10 percentile value in the control group. Multiple logistic regression analysis was done taking 12 scale scores converted into the dependent variable andL_dn , age (six levels), sex, occupation (four categories) and the interaction of age and sex as the independent variables. Significant dose-response relationships were found in the scale scores for vague complaints, respiratory, digestive, mental instability, depression and nervousness. The results suggest that the residents living around Kadena and Futenma airfields may suffer both physical and mental effects as a result of exposure to military aircraft noise and that such responses increase with the level of noise exposure (L_dn).     

EXPERIMENTAL VALIDATION OF A STRUCTURAL HEALTH MONITORING METHODOLOGY: PART III. DAMAGE LOCATION ON AN AIRCRAFT WING

This paper documents the third phase of a programme of experimental work which validates a structural health monitoring methodology based on novelty detection. In this paper, an extension of the detection method for damage location is proposed and demonstrated. The structure of interest is a Gnat aircraft wing. Although it was not possible to damage the aircraft, the method was demonstrated by determining which of a set of inspection panels had been removed.     

EXPERIMENTAL VALIDATION OF A STRUCTURAL HEALTH MONITORING METHODOLOGY: PART II. NOVELTY DETECTION ON A GNAT AIRCRAFT

This paper concerns the second phase of an experimental validation programme for a structural health monitoring methodology based on novelty detection. This phase seeks to apply one of the methods considered in the first stage of the work on a more realistic structure, namely the wing of a Gnat aircraft, as opposed to the previously investigated laboratory structure. The novelty detection algorithm used is that of outlier analysis and damage is introduced by making several copies of an inspection panel, each with a different controlled fault. All of these faults were detectable, a single feature was highlighted which proved capable of separating all the fault conditions from the unfaulted.     

COMPARISON OF COMMUNITY RESPONSE TO ROAD TRAFFIC NOISE IN JAPAN AND SWEDEN—PART II: PATH ANALYSIS

Path analysis was applied to data obtained in social surveys in Kumamoto and Sapporo, Japan, and Gothenburg, Sweden, to cross-culturally compare the causal models that describe the multiple stratum relationships between road traffic noise annoyance and endogenous and exogenous variables. Path models can estimate not only the direct effect of a variable on annoyance but also the indirect effect of the variable via other variables. The exogenous variables were selected from housing, personal and environmental factors, and the endogenous variables were selected from various activity disturbances and related effects, based on the results of correlation coefficients between variables and discrimination by factor analysis. An a priori path model was constructed at the start of the analysis and the structure equations for the endogenous variables were formulated. The standardized partial regression coefficients are called path coefficients and show the strength of the linkage between variables. A revised path model was constructed by deleting insignificant paths. The characteristics of annoyance responses were as follows: (1) annoyance caused by exhaust has the strongest relation to noise annoyance and (2) structures of noise annoyance were different between Japan and Sweden and between housing types, probably owing to differences in lifestyle.     

THE EFFECTS OF LARGE VIBRATION AMPLITUDES ON THE MODE SHAPES AND NATURAL FREQUENCIES OF THIN ELASTIC SHELLS. PART II: A NEW APPROACH FOR FREE TRANSVERSE CONSTRAINED VIBRATION OF CYLINDRICAL SHELLS

The non-linear dynamic behaviour of infinitely long circular cylindrical shells in the case of plane strains is examined and results are compared with previous studies. A theoretical model based on Hamilton's principle and spectral analysis previously developed for non-linear vibration of thin straight structures (beams and plates) is extended here to shell-type structures, reducing the large-amplitude free vibration problem to the solution of a set of non-linear algebraic equations. In the present work, the transverse displacement is assumed to be harmonic and is expanded in the form of a finite series of functions corresponding to the constrained vibrations, which exclude the axisymmetric displacements. The non-linear strain energy is expressed by taking into account the non-linear terms due to the considerable stretching of the shell middle surface induced by large deflections. It has been shown that the model presented here gives new results for infinitely long circular cylindrical shells and can lead to a good approximation for determining the fundamental longitudinal mode shape and the associated higher circumferencial mode shapes (n>3) of simply supported circular cylindrical shells of finite length. The non-linear results at small vibration amplitudes are compared with linear experimental and theoretical results obtained by several authors for simply supported shells. Numerical results (non-linear frequencies, vibration amplitudes and basic function contributions) of infinite shells associated to the first four mode shapes of free vibrations, are obtained, using a multi-mode approach and are summarized in tables. Good agreement is found with results from previous studies for both small and large amplitudes of vibration. The non-linear mode shapes are plotted and discussed for different thickness to radius ratios. The distributions of the bending stresses associated with the mode shapes are given and compared with those obtained via the linear theory.