Empirical Input Research Articles

The power of place in understanding place attachments and meanings

This contribution to a spatial theory of sense of place is an invitation to seek a better understanding of the importance of physical and concrete places in dynamic territorial attachments and meanings. The objective is to build a theoretical and methodological framework embracing a spatial approach to relations with place, and of testing it on different territories. From 130 individual interviews conducted in four rural areas, this article provides four main scientific insights: (1) a theoretical input through clarification and classification of seven concepts involved in the interactions between people and places; (2) a framework proposition in order to highlight the important role of place in defining sense of place; (3) an empirical input, with a comparative multiple case analysis; and (4) schematic representations of place attachment (based on place dependence and place identity) and place meaning (based on liked, disliked and notorious entities). Such results may be of interest to both land-use planners, in order to match facilities to affinities, and to inhabitants themselves, as tools for dialog.

An Empirical Optimization to Logistic Classification Model

Recently, the scientific community has been proposing several automatic algorithms to biomedical image segmentation procedure, being an interesting and helpful approach to assist both technicians and radiologists in this time-consuming and subjective task. One of these interesting and widely used image segmentation method could be the voxel intensity-based algorithms, e.g. image histogram threshold methods, which have been intensively improved in the past decades. Recently, an interesting approach that gained focus is the logistic classification (LC) for object detection in biomedical images. Even though the general concept behind the LC method is fairly known, the proper method’s optimization still commonly adjusted by hand which naturally adds a level of uncertainty and subjectivity in the general segmentation performance. Therefore, an empirical LC optimization is presented, offering a ITK class that performs the LC parameters optimization based on empirical input data analysis. It is worth mentioning that the LogisticContrastEnhancementImageFilter class showed here is also applied on others computational problems, being briefly explained in this document.

Performance prediction and analysis of a dead-end PEMFC stack using data-driven dynamic model

In this paper, we derive a data-driven dynamic model of a dead-end cascade-type proton exchange membrane (PEM) fuel cell. We employ an Artificial neural network (ANN) method to build the nonlinear black-box model of the PEM fuel cell stack. Both anode and cathode sides of the stack are composed of two stages which the second stages of them operate in a dead-end condition. Identification experiments are accomplished for a 400 W PEM fuel cell stack consisting of 4 cells with a 225 cm2 membrane. The empirical model inputs are time, stack current, inlet reactant gases pressures and purge interval time, and the model output is stack voltage. The ANN is trained with a set of experimental data, and the trained model is then tested and validated with an independent set of data. The results reveal good agreement between the proposed black-box model and experimental data with adequate certainty. The proposed methodology can be applied to guide the controller design and fault diagnosis of the PEM fuel cell in the near future.

¿Debe ser el terrorismo objeto de regulación constitucional? Reflexiones a partir del proceso constituyente chileno y de recientes propuestas de lege ferenda

En este artículo se trata de demostrar, con insumos empíricos, que el terrorismo no suele ser objeto de regulación constitucional, al menos en el mundo occidental. Para tal demostración, se recurre a la comparación dogmática, basada en evidencia proporcionada por comisiones de expertos, procesos participativos y el derecho comparado. De este modo, se determina que, en Occidente, el terrorismo no es una materia que se regule usualmente en las Constituciones. El valor del artículo reside en el empleo de insumos dogmáticos, conclusiones de comisiones de expertos y evidencia proveniente de procesos de participación ciudadana. Así, se llega a la conclusión de que el derecho comparado, la dogmática, los procesos de participación ciudadana y los expertos no avalan que el terrorismo sea regulado constitucionalmente.

Simulating fundamental and higher harmonic VIV of slender structures

Vortex-induced vibrations (VIV) of slender marine structures are complicated response processes, where a number of distinct frequency components might be simultaneously active. These are categorized as fundamental and higher harmonics respectively, where the latter can have a tremendous impact on the fatigue life. The present work proposes a method for time domain simulation of such multi-frequency response, by introducing a higher harmonic load term to a pre-existing semi-empirical hydrodynamic force model. Forced motion tests of a circular cylinder were simulated to experimentally and qualitatively validate the fluid-structure energy transfer. Next, the model was used to predict the response of a tension dominated riser in uniform current, for 22 velocities in the range 0.3 m/s to 2.4 m/s. The empirical input was chosen to give an average best fit with respect to the cross-flow strain measurements, which allowed dominating frequencies, fatigue damage, higher harmonics and response variability to be predicted with a high level of realism. Same set of empirical coefficients was subsequently used to predict VIV of three additional flexible pipe experiments in uniform flow, with significant differences in structural properties. The results were satisfactory for all cases, but could be improved by moderate changes to the empirical input.

Estrategias discursivas en la publicidad audiovisual de productos de bajo valor nutricional dirigidos al público infantil: felices, valientes y obesos

Los niños españoles ven una media de 9000 campañas publicitarias en televisión al año. La mayoría de ellas corresponden a alimentos de bajo valor nutricional. Dados los índices de obesidad infantil, la estrecha relación entre la publicidad dirigida a ese colectivo y el consumo de este tipo de alimentos, España aprobó en 2005 el Código de Autorregulación de la Publicidad de Alimentos Dirigida a Menores (PAOS). Este artículo tiene como objetivo analizar las estrategias discursivas utilizadas en las campañas de alimentos de bajo valor nutricional, poniéndolas en relación con el contenido del Código PAOS. Utiliza para ello una metodología mixta que integra técnicas cuantitativas para el análisis de audiencias y cualitativas para el estudio del discurso publicitario. La investigación concluye que, a diferencia de otro tipo de alimentos, la publicidad de productos de bajo valor nutricional centra su estrategia discursiva en palabras y campos semánticos vinculados a la felicidad, la acción y la diversión, entre otros. Las conclusiones apuntan asimismo a la necesidad de revisar el contenido del Código PAOS, de una mayor implicación por parte de la industria alimentaria española, de agencias y de anunciantes, con el objetivo de que la autorregulación de los contenidos publicitarios resulte realmente efectiva. La contribución original del artículo radica en la aportación teórica y empírica que toma como punto de partida la obesidad infantil en España y la interrelaciona con las estrategias discursivas de la publicidad de productos de bajo valor nutricional dirigida a los menores y el marco normativo existente.

Estimating convective heat transfer coefficients and uncertainty thereof using the general uncertainty management (GUM) framework

The rate of convective heat transfer is often required to design and optimize food engineering processes. The temperature sensor technique is the most widely used method to measure convective heat transfer coefficients (h-values). Being able to reliably determine h-values is becoming increasingly important with the advances in sophisticated food engineering modelling using it as an empirical input. This contribution uses the general uncertainty management (GUM) framework to analyze the standard uncertainty resulting in the h-value obtained with sensor experiments. It is demonstrated (using a pilot scale air blast freezer example) that the reliability in estimating h-values is often overestimated when using the methodology suggested in literature. Moreover, the uncertainty can be reduced substantially by an uncertainty-minimizing data analysis method (supplied with the study). This uncertainty analysis also provides a method for a priori determining under which conditions the temperature sensor technique will result in reliable estimations for a given food engineering application.

An Empirical Oil, Steam, and Produced-Water Forecasting Model for Steam-Assisted Gravity Drainage With Linear Steam-Chamber Geometry

Summary Presented here is a steam–assisted–gravity–drainage (SAGD) forecasting technique for oil and water production and steam injection based on linear steam–chamber geometry and an empirical form for the progression of the steam/oil interface with time. The oil forecast model generates full–cycle SAGD production profiles using three empirical inputs (the initial plateau oil rate qo,si, an exponent n, and the rising–phase–chamber angle θ) and volumetric parameters (well length, pay thickness, porosity, half–well spacing, and initial and residual oil saturation). Steam and produced–water forecasts are derived analytically using the resulting steam–chamber geometry and the heat required for the fluids, rock, and overburden. Peak rate is a direct input in this methodology, and as a result only volumetric and some thermodynamic parameters are required, but not fluid or transmissibility inputs, such as viscosity and permeability. This allows for direct use of commercial SAGD production data in the forecasting process. The model predictions are validated at a high level with field data from Devon Canada Corporation's Jackfish SAGD project and numerical simulation.

Downwind flow behaviours of cuboid-shaped obstacles: modelling and experiments

Buildings or fence-like structures are frequently modelled as cuboids in simulations of environmental assessments. Understanding flows around and downwind of typical isolated buildings, in the form of cuboids, provide insightful building disposition strategies, which are particularly useful in the field of urban planning. Fast analytical models or computational numerical models are essential for sensitivity studies of various design parameters that require validation against field/experimental data. The aim of this study is to compare in detail the robustness of analytical perturbation models and the computational fluid dynamics (CFD) k − ε turbulence models for predicting the mean wake velocity defects along the centre line downwind of the cuboids, both in the near- and far-wake regions. Depending on aspect ratios of cuboids, the decay rate of maximum velocity defect behaves differently. Moreover, the CFD code over-predicts the magnitude of maximum defect in comparison with the perturbation models, whereas it over-predicts or under-predicts when compared to actual measurements. A physical explanation has been proposed in this paper. The steady CFD models, requiring less empirical input, are shown to provide satisfactory results for approximate computations of flows in the near- and far-wake regions of cuboid buildings with appropriate settings of inflow profiles and wall function.

Running ground reaction forces across footwear conditions are predicted from the motion of two body mass components.

Although running shoes alter foot-ground reaction forces, particularly during impact, how they do so is incompletely understood. Here, we hypothesized that footwear effects on running ground reaction force-time patterns can be accurately predicted from the motion of two components of the body's mass (mb): the contacting lower-limb (m1 = 0.08mb) and the remainder (m2 = 0.92mb). Simultaneous motion and vertical ground reaction force-time data were acquired at 1,000 Hz from eight uninstructed subjects running on a force-instrumented treadmill at 4.0 and 7.0 m/s under four footwear conditions: barefoot, minimal sole, thin sole, and thick sole. Vertical ground reaction force-time patterns were generated from the two-mass model using body mass and footfall-specific measures of contact time, aerial time, and lower-limb impact deceleration. Model force-time patterns generated using the empirical inputs acquired for each footfall matched the measured patterns closely across the four footwear conditions at both protocol speeds (r2 = 0.96 ± 0.004; root mean squared error = 0.17 ± 0.01 body-weight units; n = 275 total footfalls). Foot landing angles (θF) were inversely related to footwear thickness; more positive or plantar-flexed landing angles coincided with longer-impact durations and force-time patterns lacking distinct rising-edge force peaks. Our results support three conclusions: 1) running ground reaction force-time patterns across footwear conditions can be accurately predicted using our two-mass, two-impulse model, 2) impact forces, regardless of foot strike mechanics, can be accurately quantified from lower-limb motion and a fixed anatomical mass (0.08mb), and 3) runners maintain similar loading rates (ΔFvertical/Δtime) across footwear conditions by altering foot strike angle to regulate the duration of impact. NEW & NOTEWORTHY Here, we validate a two-mass, two-impulse model of running vertical ground reaction forces across four footwear thickness conditions (barefoot, minimal, thin, thick). Our model allows the impact portion of the impulse to be extracted from measured total ground reaction force-time patterns using motion data from the ankle. The gait adjustments observed across footwear conditions revealed that runners maintained similar loading rates across footwear conditions by altering foot strike angles to regulate the duration of impact.

Estimation of the minimum fluidisation velocities in well-mixed bi-disperse fluidised beds

A method for estimating minimum fluidisation velocities in a well-mixed, bi-disperse fluidised bed of spherical particles is described where a drag model is combined with a particle packing model. The method described does not require empirical input about a specific particle mixture, and so these minimum fluidisation velocities can be estimated over wide ranges of size and density ratios. The treatment is fully non-dimensionalised. It is shown that two minimum fluidisation velocities may be defined for a well mixed bi-disperse bed: the gas speed at which fluidisation initiates determined from considering the bed as a whole, and a higher one corresponding to the balance of forces on an individual particle. The differences between bi- and mono-disperse beds are the change in particle volume fraction owing to packing, the difference in drag around individual particles compared with the average drag, and the action of the hydrostatic pressure gradient. The latter two effects tend to increase the difference between the two limits of minimum fluidisation velocity, while packing decreases it and intensifies the dependence on mass fraction of the minimum fluidisation velocities. The influence of inertia is determined from particle properties through an Archimedes number. Though the inertial effects are not large for a wide range of particles, they can start to dominate other influences on the minimum fluidisation velocities as particle diameter increases.

An efficient correlation for heat and mass transfer effectiveness in tumble-type clothes dryer drums

A heat and mass transfer effectiveness definition relevant to clothes dryers is developed in this work. A correlation is presented for determining the effectiveness of heat and mass transfer in a horizontal-axis, tumble-type clothes dryer drum with axial airflow. The correlation is a function of four measurable quantities: air mass flow rate, cloth mass, air mass in the drum, and the fall time experienced by a cloth falling the full height (i.e. diameter) of the drum. The Buckingham Pi Theorem is applied to the problem in order to derive dimensionless terms upon which the effectiveness depends. Empirical data from several dryers are used to derive an empirical correlation as a function of the dimensionless variables. Three cloth types were investigated, and a separate empirical correlation is proposed for each. Together, the drum effectiveness concept and the correlation presented provide a new, more accurate, computationally efficient, and readily implemented framework for modeling and simulating clothes dryers. It is relevant to conventional gas and electric clothes drying appliances, vapor compression heat pump dryers, and thermoelectric heat pump clothes dryers. With appropriate empirical inputs, the framework is extensible to any thermal-evaporative cloth drying systems, including radial-flow horizontal axis tumble drying drums.

The Sources of Extreme Ultraviolet and Soft X-Ray Backgrounds

Abstract Radiation in the extreme ultraviolet (EUV) and soft X-ray holds clues to the location of missing baryons, the energetics in stellar feedback processes, and the cosmic enrichment history. Additionally, EUV and soft X-ray photons help determine the ionization state of most intergalactic and circumgalactic metals, shaping the rate at which cosmic gas cools. Unfortunately, this band is extremely difficult to probe observationally due to absorption from the Galaxy. In this paper, we model the contributions of various sources to the cosmic EUV and soft X-ray backgrounds. We bracket the contribution from (1) quasars, (2) X-ray binaries, (3) hot interstellar gas, (4) circumgalactic gas, (5) virialized gas, and (6) supersoft sources, developing models that extrapolate into these bands using both empirical and theoretical inputs. While quasars are traditionally assumed to dominate these backgrounds, we discuss the substantial uncertainty in their contribution. Furthermore, we find that hot intrahalo gases likely emit an fraction of this radiation at low redshifts, and that interstellar and circumgalactic emission potentially contribute tens of percent to these backgrounds at all redshifts. We estimate that uncertainties in the angular-averaged background intensity impact the ionization corrections for common circumgalactic and intergalactic metal absorption lines by ≈0.3–1 dex, and we show that local emissions are comparable to the cosmic background only at r prox = 10–100 kpc from Milky Way–like galaxies.

Comparative analyses of flood damage models in three Asian countries: towards a regional flood risk modelling

The use of different approaches in the development of flood damage models in various countries is expected to affect flood damage modelling at a regional or global scale. Since these models are often used as tools for disaster management and decision making, it is very needful to understand the comparative similarity and differences in countries’ loss models; this can help in the overall integration for developing regional risk models and cross-country risk assessment. In this study, empirically generated generalised loss models in three Asian countries (Sri Lanka, Thailand and Japan) were compared and applied to estimate potential flood damages in two different urban river basins. For each case study, each model was normalised using cost prices and floor areas (as applied to each country) and were integrated within the Geographic Information Systems (GIS) to estimate damages for the flood events. Using the mean vulnerability index of corresponding building types for the selected countries, a single model for regional flood risk assessment was created. However, the study showed that there are variations in the vulnerability and the potential flood damage estimates of similar global building types from the three countries, despite being developed by the same approach. These are attributed to the country’s specific conditions such as building regulations and codes, GDP per capita, cost price of building materials. Our results suggest that the average vulnerability index from the countries however reduced potential errors in the estimates. Moreover, it is proposed that the average regional vulnerability model derived with empirical data inputs from all the countries for regional risk assessment and cross-country comparison. Therefore, it can predict near accurate potential flood damages, which can serve as measures for regional flood disaster risk management plans.

Simulations of Van Allen Probes Plasmaspheric Electron Density Observations

AbstractWe simulate equatorial plasmaspheric electron densities using a physics‐based model (Cold PLasma, CPL; used in the ring current‐atmosphere interactions model) of the source and loss processes of refilling and erosion driven by empirical inputs. The performance of CPL is evaluated against in situ measurements by the Van Allen Probes (Radiation Belt Storm Probes) for two events: the 31 May to 5 June and 15 to 20 January 2013 geomagnetic storms observed in the premidnight and postmidnight magnetic local time (MLT) sectors, respectively. Overall, CPL reproduces the radial extent of the plasmasphere to within a mean absolute difference of L. The model electric field responsible for E × B convection and the parameterization of geomagnetic conditions (under the Kp‐index and solar wind properties) implemented by CPL did not account for localized enhancements in the duskward electric field during increased activity. Rather, it was found to be largely dependent on the measure of the quiet time background. This property indicates that the agreement between these simulations and observations does not account for the complete set of physical processes during extreme (strong or weak) geomagnetic conditions impacting the plasmasphere. Nevertheless, at the presented resolution of the model CPL does provide good agreement in reproducing Radiation Belt Storm Probes observations of plasmaspheric density and plasmapause location.

An applied method for fatigue life assessment of engineering components using rigid-insert crack closure model

The purpose of this paper is to provide a new method for analyzing and evaluating the fatigue crack closure load and estimating the life of engineering components using RICC (Rigid-Insert Crack Closure Model), non-destructive replica technique, and a new sample. For this purpose, first, the method of solving the RICC model has been changed from linear approximation to nonlinear state and therefore, a significant improvement in the accuracy of the model results has been achieved. Then, using the model, a new formulation for the influence line in the points of sample is obtained, which has a significant accuracy. The formulation of the RICC model results in a set of equations that can help to determine the closure load and the characteristics of the load-displacement diagram using the residual crack mouth opening displacement in zero load (residual CMOD), which is the only empirical input parameter of Model. The new formulation method has been applied to a standard sample that has the same conditions as a real instance. The amount of residual crack openness in zero load (crack residual displacement) was measured using the replica technique and COD-gage simultaneously on a standard sample and were investigated using the obtained relationships and the accuracy of the outcomes. To prove the reliability, model results have been investigated through doing the experimental tests on aluminum alloys. Finally, the results obtained from the proposed relationship for the analysis and evaluation of the crack closure load and fatigue life were compared with the experimental results, which showed acceptable results.

Using ensemble Kalman filter to determine parameters for computational crowd dynamics simulations

PurposeIt is of paramount importance to ensure safe and fast evacuation routes in cities in case of natural disasters, environmental accidents or acts of terrorism. The same applies to large-scale events such as concerts, sport events and religious pilgrimages as airports and to traffic hubs such as airports and train stations. The prediction of pedestrian is notoriously difficult because it varies depending on circumstances (age group, cultural characteristics, etc.). In this study, the Ensemble Kalman Filter (EnKF) data assimilation technique, which uses the updated observation data to improve the accuracy of the simulation, was applied to improve the accuracy of numerical simulations of pedestrian flow.Design/methodology/approachThe EnKF, one of the data assimilation techniques, was applied to the in-house numerical simulation code for pedestrian flow. Two cases were studied in this study. One was the simplified one-directional experimental pedestrian flow. The other was the real pedestrian flow at the Kaaba in Mecca. First, numerical simulations were conducted using the empirical input parameter sets. Then, using the observation data, the EnKF estimated the appropriate input parameter sets. Finally, the numerical simulations using the estimated parameter sets were conducted.FindingsThe EnKF worked on the numerical simulations of pedestrian flow very effectively. In both cases: simplified experiment and real pedestrian flow, the EnKF estimated the proper input parameter sets which greatly improved the accuracy of the numerical simulation. The authors believe that the technique such as EnKF could also be used effectively in other fields of computational engineering where simulations and data have to be merged.Practical implicationsThis technique can be used to improve both design and operational implementations of pedestrian and crowd dynamics predictions. It should be of high interest to command and control centers for large crowd events such as concerts, airports, train stations and pilgrimage centers.Originality/valueTo the authors’ knowledge, the data assimilation technique has not been applied to a numerical simulation of pedestrian flow, especially to the real pedestrian flow handling millions pedestrian such as the Mataf at the Kaaba. This study validated the capability and the usefulness of the data assimilation technique to numerical simulations for pedestrian flow.

Sining Dance and Central Aceh Tourism

Sining dance is the parent of dances in Gayo. Sining dance is one of traditional dances that supports the development of tourism in Central Aceh. The purpose of this research is to analyze the Sining dance and its role of tourism in Central Aceh. The research method was qualitative descriptive and used ethnographic approach.The data collection was used techniques of observation, deep interview, and document study. Data validation was done with data triangulation, source triangulation, and method triangulation while the the analysis used data reduction, data presentation, and verification/conclusion drawing. The results show that the performance of Sining dance plyas a role as cultural attraction, Sining dance also becomes one of tourism attraction through documenter video, Sining dance in one of presentation in a show, and Sining dance is a means of entertainment. The occurence of Sining dance in tourism influences the economic benefit of Central Aceh community and automatically it can preserved Sining dance itself. This research is useful as a vehicle for developing studies on traditional art problems, and is useful as an empirical input for relevant government agencies.

Empirical sensitivity of two-dimensional nonlinear wake–cylinder oscillators in cross-flow/in-line vortex-induced vibrations

Phenomenological wake–cylinder oscillators have been extensively implemented for vortex-induced vibration (VIV) predictions. Although such models capture fundamental VIV phenomena, the maximum response estimations and comparisons with different experimental data reveal some quantitative discrepancies due to the model empiricism embedding some uncertainties through system variables. This vital issue has not been well addressed in the literature of VIV modelling. This paper presents a new comprehensive investigation into the sensitivity to empirical input variables of nonlinear wake–cylinder oscillators simulating the two-dimensionally coupled cross-flow/in-line VIV and amplified mean displacements of a flexibly mounted circular cylinder in uniform flows. The fluid–structure coupling terms are advanced by accounting for the higher-order nonlinear effects of fluctuating lift–drag forces and steady-drag dynamic magnifications, depending on the relative flow-cylinder velocities. A random sampling and variance-based sensitivity studies are carried out using Monte Carlo simulations which are computationally efficient based on the reduced-order model. This enables a large series of parametric examinations. Individual contribution, relative importance, coupling and interdependence of multiple input variables affecting output uncertainties are qualitatively and quantitatively evaluated. The Reynolds number dependence is also captured by correlating the wake and hydrodynamic coefficients with experimental data. Parametric studies highlight greater variations in the predicted amplitudes and mean displacements of the cylinder two-degree-of-freedom VIV with a lower mass ratio. Numerical findings allow for the identification of a few most influential variables to be treated as the empirically tuned coefficients. The improved understanding of model versatility and sensitivity enhances the calibration confidence and the response predictability with a reduced computational effort.

Testing the Impact of a Planning Policy Based on New Urbanist Planning Principles on Residents’ Sense of Community and Mental Health in Perth, Western Australia

There is growing concern that the built forms resulting from conventional suburban design may be adversely affecting the social well-being, sense of community, and psychological health of its residents. This study tested the premise that suburban neighborhood developments ( n = 36) designed in accordance with a New Urbanist inspired planning policy in Perth, Western Australia, improved residents’ ( n = 644) sense of community and mental health. Findings revealed that with each 10% increase in policy compliance, residents odds of experiencing high sense of community increased by 21% ( OR = 1.21, 95% CI = [1.04, 1.41]) and low psychological distress increased by 14% ( OR = 1.14, 95% CI = [1.01, 1.28]). These results add empirical input to the debate surrounding the rhetoric and purported social goals and benefits of the New Urbanism, indicating that implementation of its neo-traditionalist neighborhood design principles may help create the conditions for positive neighborhood sense of community and mental health.