Prediction of airblast-overpressure induced by blasting using a hybrid artificial neural network and particle swarm optimization

Blasting is an inseparable part of the rock fragmentation process in hard rock mining. As an adverse and undesirable effect of blasting on surrounding areas, airblast-overpressure (AOp) is constantly considered by blast designers. AOp may impact the human and structures in adjacent to blasting area. Consequently, many attempts have been made to establish empirical correlations to predict and subsequently control the AOp. However, current correlations only investigate a few influential parameters, whereas there are many parameters in producing AOp. As a powerful function approximations, artificial neural networks (ANNs) can be utilized to simulate AOp. This paper presents a new approach based on hybrid ANN and particle swarm optimization (PSO) algorithm to predict AOp in quarry blasting. For this purpose, AOp and influential parameters were recorded from 62 blast operations in four granite quarry sites in Malaysia. Several models were trained and tested using collected data to determine the optimum model in which each model involved nine inputs, including the most influential parameters on AOp. In addition, two series of site factors were obtained using the power regression analyses. Findings show that presented PSO-based ANN model performs well in predicting the AOp. Hence, to compare the prediction performance of the PSO-based ANN model, the AOp was predicted using the current and proposed formulas. The training correlation coefficient equals to 0.94 suggests that the PSO-based ANN model outperforms the other predictive models.     

Human reaction to vibrations from blasting activity – Norwegian exposure–effect relationships

Rock blasting may cause disturbances, fear, and annoyance in residential and community areas affected by such activities. These community reactions can be quite strong, even when the blasting activities and the resulting vibrations are unlikely to cause physical damage to building foundations or buildings. A socio-vibrational survey was undertaken to assess residential reactions to blasting activities. Vibration velocities were obtained for 520 respondent dwellings located in seven study areas, and compared to the residents’ assessments of environment quality. Even at low vibration values, many people report annoyance. Exposure–effect relationships with acceptable statistical error bands were obtained. The level of annoyance from long-term blasting activities (quarry blasting) was not higher than from finite periods of more intense blasting activities (road and rail tunnels). Providing information in advance of the blasting activities, can reduce community reactions. Self-reported sensitivity to vibrations was associated with significantly increased annoyance. Sensitivity to vibrations was uncorrelated with exposure to vibrations. Sensitivity to noise and sensitivity to vibration were moderately correlated.     

Indoor human response to blast sounds that generate rattles

The two major noise sources that cause environmental problems for the U. S. Army are helicopters and large weapons such as artillery, tanks, and demolition. These large weapons produce blast sounds that contain little energy above 200 Hz and that are particularly troublesome to deal with because they excite rattles in structures. The purpose of this study was to systematically test subjective response to the presence or absence of rattles in otherwise similar blast sound environments. A second purpose of the study was to test if there were structural changes that could reduce annoyance within the indoor blast sound environment. This study was done using a specially constructed test house and highly repeatable shake table to generate the blast sounds. The data clearly show that no commonly used environmental noise measure adequately describes the indoor environment when the blast excites rattles. Although the indoor blast ASEL changes by only about a decibel or so (and the indoor blast CSEL changes by even less), the subjective response changes by up to 13 dB. At low blast levels, the increase in human annoyance response is largest, and this annoyance response offset decreases to about 6 dB when the outside, flat-weighted peak sound-pressure level of the blast increases from 112 to 122 dB.     

Verification of an empirical prediction method for railway induced vibrations by means of numerical simulations

Vibrations induced by the passage of trains are a major environmental concern in urban areas. In practice, vibrations are often predicted using empirical methods such as the detailed vibration assessment procedure of the Federal Railroad Administration (FRA) of the U.S. Department of Transportation. This procedure allows predicting ground surface vibrations and re-radiated noise in buildings. Ground vibrations are calculated based on force densities, measured when a vehicle is running over a track, and line source transfer mobilities, measured on site to account for the effect of the local geology on wave propagation. Compared to parametric models, the advantage of this approach is that it inherently takes into account all important parameters. It can only be used, however, when an appropriate estimation of the force density is available. In this paper, analytical expressions are derived for the force density and the line source transfer mobility of the FRA procedure. The derivation of these expressions is verified using a coupled finite element-boundary element method.     

Community response to blasting

Annoyance due to chronic exposure to blast noise and vibration was assessed in residential areas near two surface mines and a quarry. It was found possible to base useful prediction of the prevalence of high annoyance on a metric of outdoor ground vibration related to high centiles of the long term distribution of exposure levels.     

Vibrations’ influence on Dieselness perception

Up to now, different studies dealing with vibrations’ influence on acoustics have been, in most cases, realized on global annoyance. In our case, the present study examines the vibrations’ influence on the auditory perception of Diesel character (called Dieselness in this article) of a vehicle. In addition, cultural experience is evaluated by testing two groups of Diesel owners from two European countries (respectively France and Germany). During the experiment, each population was exposed to sound only, and sound and vibrations simultaneously. This perceptual test was realized on a vibration bench (driver seat and steering wheel) with headphones. Three kinds of vehicules and six different driving situations have been tested. Results reveal no differences between French and German. Nevertheless, the adding of vibrations influences the Dieselness evaluation. The participants give slightly higher scores (more Diesel) or equal (as Diesel) with vibrations than without. However, this vibration effect is slightly dependent on the type of vehicles and on the driving situations and it appears less important for German people. In addition, for each group of participants, the other factors vehicle and driving situation have an effect on Dieselness assessment. The effect of vehicle allows to show that 3 cylinders car is significantly different from 4 cylinders and 6 cylinders cars. Finally, the interaction between driving situation and vehicle shows the strongest effect on Dieselness evaluation, among all interactions tested. The vehicle effect is dependent on the driving situation. All results and conclusions have to be taken with care in order not to generalize for all similar classification cars.     

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.     

Vibration in dwellings from road and rail traffic — Part III: towards a common methodology for socio-vibrational surveys

While a range of international standards defining noise, vibration and other physical environmental measures have been established, common methodologies for measuring people's reactions to these same environmental effects are still in their infancy. This reduces the comparability of prevalence statistics and exposure-effect relationships developed by different researchers. The public authorities are served incompatible or seemingly conflicting information from different surveys when deciding on appropriate guidelines and limits. Drawing on experiences with the 1998 Norwegian Socio-vibrational Survey and a Swedish socio-acoustic survey supplemented with vibration measures, a new Nordtest Method: NT ACOU 106 Acoustics—Assessment of annoyance by vibrations in dwellings from road and rail traffic has been defined. The method describes sampling requirements, and proposes a mandatory verbal 5-point categorical annoyance scale and an optional 11-point numerical annoyance scale, both with lower anchoring point “Do not notice”. A survey data output format is specified to allow researchers to pool data from different surveys.     

Rod Vibrations Caused by Axial Impact

The axial impact by an elastic body on an elastic-rod end with a fixed opposite end is considered. The propagation of elastic waves in the rod and the local deformations in the contact zone are taken into account. After recoil of the body, the rod performs free longitudinal vibrations, which can under certain conditions cause parametric transverse vibrations having the character of beats. Depending on the parameters of the problem, the collision time, the shock-pulse shape, and the greatest amplitude of the transverse vibrations under parametric resonance are determined.     

The response of box-like structures to weak explosions

The finite element displacement method is used to predict the vibrations of box-like buildings induced by weak blast waves. The theory is the first to incorporate experimental data to describe comprehensively the complex distortions of the blast waves by flexible structures. Numerical computations performed for three typical medium-low buildings indicate that the effects on the structure of aerodynamic variations become more important as the blast's strength increases. Wave distortions should not be neglected for nuclear blasts, although earlier work implies that this normally would be acceptable for the lower intensities associated with sonic booms from commercial supersonic aircraft. Other critical factors which govern the response are shown to be the orientation and dimensions of the building, whilst the influence of structural coupling is seen to vary appreciably with relative dimensions, edge constraints and load differentials of components.     

Particle sizing using passive ultrasonic measurement of particle–wall impact vibrations

In continuously stirred reactor vessels the non-invasive recovery of the particle size could be used to monitor the reaction process. Experimental and numerical investigations have shown empirically that the frequency of the peak vibration response arising from the particle–wall impact is inversely proportional to the particle size. The passive monitoring of these impact vibrations using an ultrasonic transducer has the potential therefore of non-invasively recovering the particle size. However, the vessel geometry, fluid loading, variable impact position and velocity, stirrer and transducer effects, and noise levels make this problem very complex. There are a large number of system parameters and this makes empirical derivations of cause and effects extremely difficult. The first objective of this paper is to derive an analytical expression for the vibrations arising from a spherical particle impacting a circular plate. Using a series expansion in terms of the plate loss parameter, an expression for the frequency of the peak pressure in terms of the system parameters is derived. In particular, its explicit dependency on the impacting particle size and the impact velocity is found. The inverse problem of recovering the particle size from the experimental data is then investigated. A set of experiments are described where the impact vibrations are recorded using an ultrasonic transducer attached to the rear of a thin plate. The results show that it is possible to recover the particle size using this approach. Data from a second set of experiments, involving multi-particle impacts with a vessel wall in a continuously stirred reactor, are then used. The inverse problem of recovering the particle size from the vibration spectrum was then investigated with encouraging results.     

Bound formula for determining the fundamental frequency

The extent of interference with various activities was studied among populations in areas exposed to noise from aircraft, road traffic, trains and tramways. When areas with differences in the extent of general annoyance were compared, similar differences in the extent of the various activity interferences were found, except for those due to vibrations. As an example of the differences in the activity interference pattern, it was found that road traffic noise interfered significantly less with speech than train noise, whereas both noise types caused roughly the same interference with rest/sleep. The results suggest that uniform weighted annoyance scores incorporating various kinds of activity interference are not valid for all types of environmental noises. Interference due to vibrations probably has to be treated separately from that due to noise.     

Inquiry on noise causing complaints in residential areas near chemical plants

Industrial noise may lead to noise annoyance in residential areas, in particular when such areas are located close to industrial plants. Specific reduction of noise requires detailed knowledge of the complaints from the residential neighbourhood and their relation to the noise source.The membership companies of the German Federation of Chemical Industry have recorded 230 noise complaints from 1977 to 1979. In relation to these complaints, parameters, e.g. nature of noise source, noise character, time of noise occurrence, meteorological conditions, were investigated and statistically evaluated.Fifty complaints out of the 230 were quantitatively evaluated with respect to the background and noise level at the location of complaint. It resulted, that only 16% of the complaints are based on broad band noise, whereas 84% on impulse noise and single tones. Broad band noise causes complaints beginning at 65 dB(A), impulse noise at 56 dB(A) and single tones at 50 dB(A).     

炸药混凝土中爆炸能量释放规律的研究

 通过对炸药在混凝土中爆炸的并行计算,分析其数值计算结果,并对爆炸力学基础理论进行研究后认为：炸药在土岩介质中爆炸,炸药能量将通过爆炸空腔中爆炸产物内冲击波的多次往复反射的方式进行释放,同时破坏并推动土岩介质移动,土岩介质与爆炸气体的界面在爆腔内稀疏波的作用下进行持续减速扩张运动。     

Noise annoyance from stationary sources: relationships with exposure metric day-evening-night level (DENL) and their confidence intervals

Relationships between exposure to noise [metric: day-evening-night levels (DENL)] from stationary sources (shunting yards, a seasonal industry, and other industries) and annoyance are presented. Curves are presented for expected annoyance score, the percentage "highly annoyed" (%HA, cutoff at 72 on a scale from 0 to 100), the percentage "annoyed" (%A, cutoff at 50 on a scale from 0 to 100), and the percentage "(at least) a little annoyed" (%LA, cutoff at 28 on a scale from 0 to 100). The estimates of the parameters of the relations are based on the data from a field study (N=1875) at 11 locations (2 shunting yards, 1 seasonal industry, 8 other industries) in the Netherlands. With the same (yearly) DENL, the seasonal industry causes less annoyance than the other industries, while the other industries cause less annoyance than the shunting yards. It appears that annoyance caused by vibrations from shunting yards and annoyance caused by noise from through trains are (partly) responsible for the relatively high annoyance from shunting yards. The relatively low annoyance from the seasonal industry presumably is related to the presence of a relatively quiet period. Results for the two shunting yards and the seasonal industry are based on fewer data than the other industrial sources, and are indicative. The same patterns of influence of age and noise sensitivity that are generally found are also found in this study. For comparison, results regarding transportation sources are also given, including previously unpublished results for expected annoyance.     

A- and C-weighted sound levels as predictors of the annoyance caused by shooting sounds,for various façade attenuation types

In a previous study on the annoyance caused by a great variety of shooting sounds [J. Acoust. Soc. Am. 109, 244-253 (2001)], it was shown that the annoyance, as rated indoors with the windows closed, could be adequately predicted from the outdoor A-weighted and C-weighted sound-exposure levels [ASEL (L(AE)) and CSEL (L(CE))] of the impulse sounds. The explained variance in the mean ratings by (outdoor) ASEL was significantly increased by adding the product (L(CE) - L(AE))(L(AE)) as a second variable. In the present study it was investigated to which extent the additional contribution of the second predictor is also relevant for fa?ade attenuation types with lower and higher degrees of sound isolation than applied previously. Twenty subjects rated the indoor annoyance caused by 11 different impulse types produced by firearms ranging in caliber from 7.62 to 155 mm, at various levels and for five fa?ade attenuation conditions. The effect of fa?ade attenuation on the ratings was large and consistent. In all conditions, an optimal prediction of the annoyance was obtained with outdoor ASEL as the first, and (L(CE) - L(AE))(L(AE)) as the second predictor. The benefit of the second predictor, expressed as the increase in the explained variance, ranged from 2.5 to 55 percent points, and strongly increased with the degree of fa?ade attenuation. It was concluded that for the determination of the rating sound level, the acoustic parameters ASEL and CSEL are very powerful. In addition, the results showed that for the whole set of impulses included, the annoyance could also be predicted very well by the weighted sum of indoor ASEL and the product (L(CE) - L(AE))(L(AE)).     

Subjective evaluation of work environment with special reference to noise

The presence of subjective noise annoyance was investigated among workers in a machine factory and a textile mill by using a questionnaire. The relation between annoyance due to noise and annoyance caused by other factors in the work environment was also investigated. The results show that annoyance due to noise exposure was common in both factories. Apart from the relation to the noise level, other acoustical characteristics, such as frequency spectrum and intensity, as well as differences between background and peak levels seem to determine the extent of annoyance. In the machine factory, the general satisfaction at work was significantly less among workers who had reported annoyance from noise, insufficient natural and artificial daylight and dust. In the textile mill noise and dust as well as monotonous work and fast working pace were of importance for the general satisfaction at work. Headache and tiredness were more common in the textile mill. The techniques used in the study could be applied to obtain further information on other industrial noise exposure criteria than hearing damage to serve as a basis for standards for annoyance.     

A fuzzy rule based framework for noise annoyance modeling

Predicting the effect of noise on individual people and small groups is an extremely difficult task due to the influence of a multitude of factors that vary from person to person and from context to context. Moreover, noise annoyance is inherently a vague concept. That is why, in this paper, it is argued that noise annoyance models should identify a fuzzy set of possible effects rather than seek a very accurate crisp prediction. Fuzzy rule based models seem ideal candidates for this task. This paper provides the theoretical background for building these models. Existing empirical knowledge is used to extract a few typical rules that allow making the model more specific for small groups of individuals. The resulting model is tested on two large-scale social surveys augmented with exposure simulations. The testing demonstrates how this new way of thinking about noise effect modeling can be used in practice both in management support as a "noise annoyance adviser" and in social science for testing hypotheses such as the effect of noise sensitivity or the degree of urbanization.     

Improvement of Zwicker’s psychoacoustic annoyance model aiming at tonal noises

According to 4 acoustical parameters of noise samples (i.e., loudness, sharpness, fluctuation strength and roughness), Zwicker’s psychoacoustic annoyance model can be used to estimate the relative degree of noise annoyance. However, this model cannot be well applied to compare the annoyance degrees of tonal noises and atonal noises. In order to improve its estimation effect on tonal noises, 3 groups of noise samples were selected randomly, i.e., 27 low-frequency tonal noise samples induced by a 1000 kV transformer with A-weighted equivalent sound pressure levels ranging from 41.2 dBA to 73.0 dBA; 30 low-, mid- or high-frequency tonal/atonal noise samples with loudness levels ranging from 60 phon to 80 phon; and 60 other noise samples with A-weighted equivalent sound pressure levels ranging from 40.7 dBA to 75.0 dBA. Laboratory listening tests were conducted on the above 3 sample groups respectively via an 11-point numerical scale. The Zwicker’s psychoacoustic annoyance model was improved by taking tonality into account, and introducing the evaluation result of the first noise sample group (1000 kV transformer noise samples) to determine the coefficients in the model. The applicability of the improved model was examined by the evaluation results of the other two groups as well as the data in a previous research on annoyance of 220 kV/500 kV transformer noises. Results show that the improved model can estimate the relative annoyance degrees caused by various types of tonal/atonal noises much more accurately.     

Dominant frequencies of train-induced vibrations

This paper investigates the dynamic characteristics of ground vibrations induced by moving vehicles including the mass rapid transit system, high-speed train railway, and general railway on bridges, embankments, and in tunnels using field experiments and theoretical solutions. The results indicate that train-induced ground vibrations at the trainload dominant frequencies are significantly large for both subsonic and supersonic train speeds, and the vibrations from carriage natural frequencies and engine frequencies are minor. For trains moving on bridges, the resonant vibrations are serious when the natural frequencies of the bridge are close to the trainload dominant frequencies, but resonance does not occur when the carriage natural frequencies and trainload dominant frequencies match. The trainload dominant frequency and its influence factor can be computed using the two simple equations deducted in this paper.