Source Descriptors Research Articles

Uncertainty of structure-borne sound source quantities and the installed power from interlaboratory test results according to EN 15657

Structure-borne sound sources affect the acoustic quality inside buildings. Based on many years of research, methods have been standardised to characterise structure-borne sound sources in the laboratory (EN 15657) and to predict the sound transmission from these sources when installed in buildings (EN 12354-5). This contribution is about the uncertainty of the source descriptors used in EN 15657 and the predicted installed sound power which is the input quantity for EN 12354-5. Recently an interlaboratory test with 7 participating laboratories has been performed. The task was to measure the blocked force, free velocity and mobility of an artificial source and the blocked force of the ISO tapping machine. From the evaluation of the measurement results estimates for the uncertainties of the source quantities and the installed power could be deduced.

Structure-borne sound sources in buildings – Estimating the uncertainty of source properties and installed power from interlaboratory test results

A low immission due to structure-borne sound sources is a major component of the acoustic quality inside buildings. After many years of research, methods have been standardised to characterise such sources (EN 15657) and to predict their impact in buildings (EN 12354-5). This contribution is dedicated to the question what the uncertainty of the source descriptors and the predicted installed sound power is. To answer this question, an interlaboratory test with an artificial source was performed. Altogether seven laboratories participated, and estimates for the uncertainties of the source quantities could be deduced from the measurement results. Additionally, measurements were performed with a standardised structure-borne sound source, the ISO tapping machine, by all participating laboratories. The measured source quantity for this source turned out to be in good agreement with the theoretically predicted values thereby validating this theoretical prediction.

Human Olfaction at the Intersection of Language, Culture, and Biology

The human sense of smell can accomplish astonishing feats, yet there remains a prevailing belief that olfactory language is deficient. Numerous studies with English speakers support this view: there are few terms for odors, odor talk is infrequent, and naming odors is difficult. However, this is not true across the world. Many languages have sizeable smell lexicons - smell is even grammaticalized. In addition, for some cultures smell talk is more frequent and odor naming easier. This linguistic variation is as yet unexplained but could be the result of ecological, cultural, or genetic factors or a combination thereof. Different ways of talking about smells may shape aspects of olfactory cognition too. Critically, this variation sheds new light on this important sensory modality.

Probabilistic hazard maps for operational use: the case of SO2 air pollution during the Holuhraun eruption (Bárðarbunga, Iceland) in 2014–2015

The Holuhraun fissure eruption (Iceland) in 2014–2015, which originated from the Barðarbunga volcanic system, was exceptional in several respects. It lasted 6 months and, throughout its duration, it released up to 9.6 Mt of SO2 in the atmosphere. The main recorded hazard affecting the entire country over the 6 months was the constant presence of a low-level gas cloud that led to recurrent air pollution episodes. The Icelandic Meteorological Office responded to this human health hazard by (1) setting up a forecasting system to anticipate the distribution of SO2 over Iceland and (2) preparing probabilistic hazard maps to support the decisions taken by the Icelandic Civil Protection in demarcating the accessible area around the eruption site. This paper introduces some technical aspects of the application of the CALPUFF numerical model to this eruption like the SO2 dispersal forecasting setup, the volcanic source numerical description, and the Monte Carlo procedure adopted for the creation of the probabilistic hazard maps. CALPUFF-based maps were created in January 2015, when the eruption was still ongoing, with the assumption that the eruption would be continuing with the same intensity. Maps for the entire country and for a smaller domain were produced, the latter showing the likelihood to exceeding an hourly concentration of 2600 μg/m3 (1 ppm) of SO2 for the spring season, a level chosen by the Icelandic Civil Protection for the delineation of the area of restricted access around the eruption site. As during the eruption there was no time for a rigorous evaluation of the model accuracy, we then undertook a retrospective analysis of CALPUFF model performance comparing the forecasted hourly SO2 concentration with real-time measurements at key-sites. The model did reproduce the hourly observations (the maximum within a 24-running window) with a level of agreement of 50.6% in Mývatn (85 km from the eruption site) and 50.4% in Reykjavik (258 km), when instances of null pairs have been removed. In Mývatn, the model overestimated the concentration more than 22% of the time. In Hofn (104 km), the model accuracy is 81.7% and occurrences of underestimation are higher than 11% of the time. In Reyðarfjorður (at 124 km), the model accuracy is assessed to be 82.7% and the model overestimates occurring 15.1% of the time. Possible explanations for the observed mismatch between model results and measurements include the spatial resolution of meteorological data field, the capability into reproducing chemical reactions of SO2 in atmosphere, and the reduced extension of the numerical domain. In addition, the model performance is strongly dependent on the source descriptors (e.g., strength of the SO2 flux and injection height) that, in this contribution, have been kept constant over long periods—neglecting, in this way, the natural variability of a dynamic emission of SO2. This consideration points toward the need of frequent and high-quality observation data for the initialization of dispersal numerical model. In light of this retrospective analysis, the probabilistic hazard maps possibly over-estimated the area exposed to high level of SO2 concentration. All the same, this paper reports on how quantitative probabilistic hazard mapping can be used for mitigating the health risk of volcanic SO2 emissions during a volcanic crisis to the benefit of operational hazard monitoring in support an effective crisis response.

Semantic vs. Empirical Issues in the Bear Diversionary Baiting Controversy

Conventional North American management of human-bear conflicts assumes that bears become more dangerous and destructive of human property if the bears have become food conditioned. Bears perceived as dangerous or destructive are usually killed. Conflict management to protect both people and bears focuses on minimizing bear access to anthropogenic foods. That can work where bears have access to sufficient wild foods. During famines of profitable wild foods, however, the key to minimizing conflicts can be providing food to bears – so-called diversionary baiting. Wild food supply is only one of numerous factors determining why provisioning bears intensifies conflicts in some situations, but minimizes conflicts in other situations. Identifying and quantifying the role of each factor is best done through formation of a more comprehensive conceptual model, followed by hypothesis derivation and testing. Literature synthesis and paradigmatic reconceptualization have thus far been hampered by terminological ambiguity. To overcome this constraint, we propose systematically integrated definitions for key terms: (a) conflict zones and sites, conflict foods, provisioning, incursionary feeding, baiting for diversion and other purposes; (b) numerous sorts of food conditionning: respondant, instrumental, opportunistic, transient, compensatory, agonistically induced, preferential, location- specific, person- specific, direct, indirect. (c) Food source descriptors: presence, abundance, density, accessibility, harvestability, availability, attractiveness, palatability, profitability, preference, reliability (predictability), and microhabitat suitability.

The skeleton-functional model of the cause-effect regularities of the managed behavior of technical systems

Are stated shareable systematic requirements produced to the simulators of operation to and the principles of driving by the conditions of technical systems (TS). Are detected the typed features of source descriptors TS impeding the construction of their simulators. Is proposed the structural- functional simulator of the processes of the control behavior of TS in the form of the IDEF0 chart allowing pictorial to present and analyze the regularities of their cause-effect relations from general system attitudes. The detail of the attributes of this simulator lets to ground and to develop the shareable systematic methods of the formalization of the verbal descriptors of the principles of driving and operation TS.

Indoor noise exposure at home: a field study in the family of urban schoolchildren

This article aims at evaluating indoor noise levels at home and investigating the factors that may influence their variability. An 8-day noise measurement campaign was conducted in the homes of 44 schoolchildren attending the public primary schools of Besançon (France). The presence of the inhabitants in the dwelling and the noisy events occurring indoors and outdoors was daily collected using a time-location-activity diary (TLAD); 902 time periods were analyzed. The indoor noise level increased significantly with the outdoor noise level, along with the duration of the presence or level of activity of the inhabitants at home. However, this effect may vary according to the period of day and the day of the week. Moreover, a significant part of the day and evening indoor noise level variability was explained when considering the TLAD variables: 46% and 45% in the bedroom, 54% and 39% in the main room, respectively. Our results highlight the complexity of the indoor environment in the dwellings of children living in an urban area. Combining the inhabitant presence and indoor noise source descriptors with outdoor noise levels and other dwelling or inhabitant characteristics could improve large-scale epidemiological studies. However, additional efforts are still needed, particularly during the night period.

PROTOCOL: Psychosocial Interventions for School Refusal Behavior With Elementary and Secondary School Students

PROTOCOL: Psychosocial Interventions for School Refusal Behavior With Elementary and Secondary School Students

Using Open Source Computational Tools for Predicting Human Metabolic Stability and Additional Absorption, Distribution, Metabolism, Excretion, and Toxicity Properties

Ligand-based computational models could be more readily shared between researchers and organizations if they were generated with open source molecular descriptors [e.g., chemistry development kit (CDK)] and modeling algorithms, because this would negate the requirement for proprietary commercial software. We initially evaluated open source descriptors and model building algorithms using a training set of approximately 50,000 molecules and a test set of approximately 25,000 molecules with human liver microsomal metabolic stability data. A C5.0 decision tree model demonstrated that CDK descriptors together with a set of Smiles Arbitrary Target Specification (SMARTS) keys had good statistics [κ = 0.43, sensitivity = 0.57, specificity = 0.91, and positive predicted value (PPV) = 0.64], equivalent to those of models built with commercial Molecular Operating Environment 2D (MOE2D) and the same set of SMARTS keys (κ = 0.43, sensitivity = 0.58, specificity = 0.91, and PPV = 0.63). Extending the dataset to ∼193,000 molecules and generating a continuous model using Cubist with a combination of CDK and SMARTS keys or MOE2D and SMARTS keys confirmed this observation. When the continuous predictions and actual values were binned to get a categorical score we observed a similar κ statistic (0.42). The same combination of descriptor set and modeling method was applied to passive permeability and P-glycoprotein efflux data with similar model testing statistics. In summary, open source tools demonstrated predictive results comparable to those of commercial software with attendant cost savings. We discuss the advantages and disadvantages of open source descriptors and the opportunity for their use as a tool for organizations to share data precompetitively, avoiding repetition and assisting drug discovery.

The influence of cross-order terms in interface mobilities for structure-borne sound source characterization

For the characterization of structure-borne sound sources with multi-point or continuous interfaces, substantial simplifications and physical insight can be obtained by incorporating the concept of interface mobilities. The applicability of interface mobilities, however, relies upon the admissibility of neglecting the so-called cross-order terms. Hence, the objective of the present paper is to clarify the importance and significance of cross-order terms for the characterization of vibrational sources. From previous studies, four conditions have been identified for which the cross-order terms can become more influential. Such are non-circular interface geometries, structures with distinctively differing transfer paths as well as a suppression of the zero-order motion and cases where the contact forces are either in phase or out of phase. In a theoretical study, the former four conditions are investigated regarding the frequency range and magnitude of a possible strengthening of the cross-order terms. For an experimental analysis, two source–receiver installations are selected, suitably designed to obtain strong cross-order terms. The transmitted power and the source descriptors are predicted by the approximations of the interface mobility approach and compared with the complete calculations. Neglecting the cross-order terms can result in large misinterpretations at certain frequencies. On average, however, the cross-order terms are found to be insignificant and can be neglected with good approximation. The general applicability of interface mobilities for structure-borne sound source characterization and the description of the transmission process thereby is confirmed.

Laser Doppler vibrometry and near-field acoustic holography: Different approaches for surface velocity distribution measurements

Nowadays there are several direct or indirect measurement methods for the determination of the surface velocity in vibrating structures, but two of them seem to be the most promising and interesting, in particular for vibro-acoustic problems: laser Doppler vibrometry (LDV) and near-field acoustic holography (NAH). While LDV is a direct laser-based vibration measurement technique, NAH allows the determination of the particle surface velocity starting from simultaneous microphone measurements performed on a plane array positioned near the vibrating object, although with some limitations. In this work the two structural and acoustic techniques are compared on a simple laboratory case, specifically a plate, in order to carefully and quantitatively assess the measurement uncertainty in the indirect NAH method used to estimate the vibration velocity. Advantages and disadvantages of the two methods are discussed briefly. This study was conducted within the European Growth Project “ACES” (Optimal Acoustic Equivalent Source Descriptors for Automotive Noise Problems) GRD1-1999-11202.

Towards a structure-borne sound source characterization

Characterization of mechanical sources is complicated since up to six forces and moments contribute at a contact and the response at one contact is the result of forces and moments at all contacts. For the transmission process, the quantity of prime interest is the complex power, and, therefore, a proper source characterization should relate to it. The source descriptor does so and offers a consistent base for studies of source characterization. Theoretical and experimental progress on the source descriptor is reviewed. From inspection of the source descriptors and the mobilities from which they are composed, it is observed that the uncoupled component source descriptors can establish the bandwidth and dominant components of excitation. The ‘signatures’ of the point mobilities required allows contacts to be classified as mass-, stiffness- or resonance-controlled component, establishing simplifications with respect to source characterization.

Remarks on acoustical descriptors for explosions in air

Currently, ISO/TC43/SC1/WG51 is collecting ‘‘experiences’’ with measuring and predicting shooting noise. One goal of this working group is to write a guideline for the measurement of source data of shooting noise, taking into account the special characteristics of these high energy, impulsive blasts. There are three special aspects with shooting noise: First, there are nonlinear effects close to the source. Second, the strong directivity of blast sources plays a very important role. Third, in contrast to most of the continuous noise sources, blasts are single events which involve coherence effects during source and receiver measurements. Therefore, a dedicated set of emission data has to be introduced to describe a blast source with respect to sound propagation models. The presentation will discuss the definition of a set of appropriate source descriptors for muzzle blasts. The source will be treated as a linear spherical source with directivity. Its intensity will be defined in the far field and its directivity pattern will describe the acoustical strength. The radius of this artificial source depends on the blast energy and is an important parameter when determining the appropriate measurement distance for source measurements.

Displacements and stresses induced by a point source across a plane interface separating two elastic semi‐infinite spaces: An analytical solution

The problem of computing the static deformations and stresses produced by a point source in a homogeneous infinite medium was solved by Volterra [1907] in a closed analytical form at the beginning of this century. The similar problem of computing fields generated by point sources in a homogeneous half‐space bounded by a free surface was later studied by Steketee [1958a,b] and several others [see Okada, 1985, 1992], who focused on point as well as on rectangular fault sources of interest in seismology. Here the model taken into account consists of two elastic half‐spaces characterized by different elastic properties (rigidity modulus μ and Poisson coefficient v ) and separated by a planar interface: assuming that a point source is active in one half‐space, static deformations and stresses generated by the source in the whole space are computed. The similar problem of two half‐spaces welded together was solved by Heaton and Heaton [1989], but they imposed the simplifying constraint that both materials are Poissonian ( i.e., both have the same Poisson coefficient v=0.25). The present approach, which is based on the Galerkin vector method, is general and applicable to an arbitrary point source. In this paper the computations have been carried out explicitly only for the special case of a dislocation source having the form of a strike‐slip double couple. The solution is provided in a closed analytical form by means of expressions involving the source descriptors (position and intensity) as well as the elastic parameters of the heterogeneous medium. The solutions have been illustrated and discussed with special attention given to the dependence of the displacement and stress components on the elastic parameters of the model. One interesting finding concerns the limiting case when the rigidity modulus of the half‐space not containing the point source is equalized to zero. Although the solution in this half‐space no longer makes sense, the solution in the other reduces exactly to the one computed for a half‐space with a free surface, that is, to the solutions computed by Steketee [1958a] and Okada [1985] following an alternative approach.

Use Of The Source Descriptor Concept In Studies Of Multi-Point And Multi-Directional Vibrational Sources

A study of the influence of multi-point and multi-component coupling on structure-borne sound source characterization has been carried out. In particular, the effects of cross-coupling between different components of excitation and motion at a contact point have been examined. Theoretical results are supported by results of experiments on real machines, a family of fan units. The significance of the various components of excitation and motion is interpreted in terms of the source descriptor, a quantity defined on a power basis. It is shown that measured source descriptors associated with force and moment can be equally important and, accordingly, none can be excluded a priori. It is also shown that multi-point and multi-component coupling can have a profound influence. The ability of the source to impart vibrational power at global anti-resonances of the source structure is demonstrated. In addition, this ability is spectrally transposed to a higher frequency range than that predicted from a single point, single component analysis.

Performance prediction of tangentially fired utility furnaces by computer model

The design and performance guarantee of fossil fuel fired utilities require that furnace performance be predicted within fairly narrow limits. Acceptability of a calculational model requires that it be at least as accurateas the empirically based design standards it is intended to supplant. This is achieved by a simple model which views the furnace as an equivalent rectangular parallellipiped divided, usually, into 20 to 30 horizontal slices. These are further differentiated as “firing” heat released by combustion of fuel and air input) and “non-firing” slices. In the program this results in the specification of three empirically based “source descriptors”: (1) the extent of the combustion xone (RZH). (2) the combustion xone position relative to the furnace (RZC), and (3) the emissivity of the radiating components in the furnace as specified by the “FE operator”. It has been found that restricting radiative emissivity to CO2 and H2O components in furnances of large dimension on the order of 40×40×80 ft) is inadequate. The development of the “FE operator” followed as a consequence. Its value has been established in the range 1.18 to 1.22 for gas firing and 1.40 to 1.55 for oil firing.