Full-scale Values Research Articles

Investigation of the parameters influence of the oxy-fuel burner and the test bench parameters on the deviation of the model similarity criterions from the full-scale values

The article presents the results of a study of the workflow parameters influence in the full-scale and model burners of the combustion chamber oxy-fuel combined cycle on the deviation of similarity criteria from full-scale values. The variable parameters are the pressure and velocity of the fluid under model conditions, as well as the power of model and full-scale burners. The supercritical parameters of the working fluid in the cylindrical sections of the combustion zone at a pressure of 30 MPa and a temperature of 1570 ℃ were taken as full-scale conditions. In this paper, the dependences of the deviations of hydrodynamic and thermophysical similarity criteria on the speed and pressure of the combustion products of an oxygen-fuel mixture with carbon dioxide in the working zone of the test bench for burners are obtained. The parameters of the working fluid and the power of model burners are obtained, at which the values of the criteria deviations are minimal.

Cognitive profiles in pediatric unilobar vs. multilobar epilepsy.

We aimed to determine how cognitive impairment relates to the extent of the presumed epileptogenic zone in pediatric focal epilepsies. We analyzed the cognitive functions in unilobar compared to multilobar focal epilepsy patients that underwent neuropsychological testing at a tertiary epilepsy center. We assessed cognitive functions of pediatric focal epilepsy patients with the German version of the Wechsler Intelligence Scales that measures full-scale IQ and subcategories. We assessed differences in IQ and epilepsy-related variables between unilobar and multilobar epilepsy patients. We included 62 patients (37 unilobar, 25 multilobar), aged 10.6±3.7 years. Full-scale IQ values were significantly higher in unilobar (93.6±17.7, 95% CI 87.7-99.6) than in multilobar epilepsy patients (77.3±17.2, 95% CI 69.3-85.0; p=0.001). In all but one IQ subcategory (working memory), significantly higher values were measured in unilobar than in multilobar epilepsy patients. The proportion of unilobar epilepsy patients with severe cognitive impairment (8.3%) and below-average intelligence (30.5%) was lower compared to multilobar epilepsy patients (47.6% and 61.9%; p=0.002 and p=0.021, respectively). Epilepsy onset occurred earlier in multilobar (4.0 years, 95% CI 2.6-5.5, SD±3.4 years) than in unilobar epilepsy patients (7.0 years, 95% CI 5.5-8.5, SD±4.4 years, p=0.008). Pediatric multilobar epilepsy patients face more cognitive issues than unilobar epilepsy patients on average. Our findings should help to identify children and adolescents who are most at risk for impaired cognitive development. A limitation of our study is the simple division into unilobar and multilobar epilepsies, with no specific account being taken of etiology/epilepsy syndrome, which can have a profound effect on cognition.

Intelligence Quotient Outcome Following Epilepsy Surgery in Pediatric Age – A Systematic Review and Meta-Analysis

There is a deep-rooted correlation between refractory epilepsy in pediatric age and intelligence development. However, little is known about whether surgical procedures used in pediatric epilepsy treatment can affect Intelligence Quotient (IQ) or not. Factors that might influence postoperative IQ are also a matter of study in several articles. To tackle these issues, a systematic review with meta-analysis was conducted with the terms “epilepsy”, “epileptic”, “surgery”, “surgical”, “Wechsler Scale” and “intelligence tests” in PubMed, the Cochrane Library, EMBASE and Clinical Trials.gov. A descriptive data synthesis was carried out to address each of the objectives and then a metaanalysis using a random effects model was conducted. A meta-regression was performed to ascertain possible factors that could influence postoperative IQ. The meta-analysis of the studies included found a mean difference between postoperative and preoperative full-scale IQ values of 1.014 standardized points (p < 0.001). Among all the articles regarding curative surgeries, only three reported an overall significant improvement in IQ after surgery. Regarding palliative procedures, both studies with anterior corpus callosotomy reported a significant improvement in full-scale IQ values two years after surgery. The meta-regression performed did not find any predictors of change in full-scale IQ.

Adolescents' Empowerment for Mental Health Literacy in School: A Pilot Study on ProLiSMental Psychoeducational Intervention.

Adolescence is a critical life phase for mental health and anxiety an emerging challenge for adolescents. Psychoeducational interventions to promote mental health literacy (MHL) on anxiety in adolescents are needed. This study aimed to test the primary outcome of a future full-scale trial: improvement of adolescents’ anxiety MHL components on recognition, prevention strategies, and self-help strategies. A sample of 38 adolescents, 24 (63.2%) females and 14 (36.8%) males, with an average age of 14.50 years (SD = 0.89) participated in this study. Each class was allocated to the intervention group (IG, n = 21) or the waiting list control group (WLCG, n = 17) with single-blinded randomization. MHL was assessed using the QuALiSMental. The ProLiSMental psychoeducational intervention consists of four or eight weekly sessions of 90 or 45 min for adolescents, using different active pedagogical methods and techniques. There also are initial and final sessions with adolescents, legal guardians, and teachers. There was a significant improvement with a small to relatively strong effect size in many dimensions of anxiety MHL components. This study suggests the progression to the full-scale trial and values the important role of mental health and psychiatric nurses in the adolescents’ empowerment for MHL in schools.

Time-varying structural reliability assessment method: Application to fiber reinforced composites under repeated impact loading

Reliability evaluations play a significant role in engineering applications to ensure the serviceability and safety of advanced structures such as those made of composites. Here, a dynamic reliability evaluation analysis based on the probability density evolution Method (PDEM) has been adapted to assess the reliability of composite structures under uncertainties within the material properties and the external loadings. A Back-Propagation Neural Network approach is employed to identify the system's nonlinear structural response, which is often the case under large deformations. To exemplify, a split Hopkinson pressure bar system was employed to mimic the mechanical behavior of a polypropylene/fiberglass woven composite plate structure under repeated high-strain rate impacts. Subsequently, the reliability prediction was performed offline via the system model and integration of uncertainties, as well as via an online SHM-based approach, and compared to full-scale (direct) experimental reliability values by repeating the impact tests on a population of samples. A material degradation factor has been introduced within the PDEM approach to account for surface damage induced during impacts. Results clearly showed the accuracy of the PDEM in predicting the remaining reliability of the composite after each impact. The method is generic and may be applied to other types of loadings and structures.

Jogo para o ensino de reabilitação na pessoa submetida a artoplastia da anca: estudo de caso

Objetivo: O estudo teve como objetivo conhecer a opinião dos estudantes de especialização em enfermagem de reabilitação em contexto de ensino clínico sobre a utilização de um Jogo para o ensino dos cuidados de reabilitação à pessoa submetida a Artoplastia da Anca. Métodos: Trata-se de estudo de caso múltiplo, descritivo e exploratório, no qual foi desenvolvido e aplicado o jogo Reabilit´Arte. Os participantes foram selecionados através de uma amostragem em bola de neve. Para a recolha de dados foi realizada uma breve caracterização sociodemográfica, aplicação do Instrumento de Avaliação de Estratégias de Formação (IAEF), e perguntas abertas sobre as vantagens e desvantagens do jogo. Para a análise das perguntas abertas foi utilizado o software Atlas-ti versão 8.0. Resultados: A amostra foi constituída por 9 estudantes da pós-licenciatura em enfermagem de reabilitação. Sobre a avaliação da utilização do jogo observa-se que em média da aplicação da escala total os valores variaram entre 80 e 100 muito acima do valor médio da escala. Da análise dos dados, emergiram no âmbito das vantagens da aplicação do jogo as subcategorias: reforço do ensino, facilidade da aprendizagem, participação ativa, motivação e memória visual. No âmbito das desvantagens, com menor frequências são apresentadas o fator tempo e as características dos participantes. Conclusão: O jogo foi avaliado positivamente, revelando que a intervenção do enfermeiro especialista em enfermagem de reabilitação através de um jogo pode ser útil para promover capacidades adaptativas com vista ao autocontrolo e autocuidado nos processos de transição saúde/doença e ou incapacidade. Palavras-chave: Educação em Saúde; Materiais de Ensino; Artroplastia de Quadril; Enfermagem em Reabilitação

Loads and response on flexible conical and cylindrical fish cages: A numerical and experimental study based on full-scale values

This paper presents drag forces from uniform water current on two flexible net cage designs, commonly used in Norwegian fish farming, obtained through model-scale testing and numerical simulations. The primary focus is on the comparison between model tests and numerical simulations and performance of the numerical model for the different net cage designs. The two designs were a cage with a cylindrical main section with straight walls and conical bottom with a sinker tube weight system and a cage where both the main section and bottom has a conical shape. The latter cage has a central weight instead of a sinker tube. The effect of the governing parameters was explored by varying the design and loads of the weighting system. Both physical tests and numerical simulations revealed increased drag forces and reduced ability for deformation when increasing the load from the weighting system. Lower weight system load or weight system designs that allow for more deformation decrease the loads on the net cage. Although it was not a focus in the present work, fish welfare is dependent on sufficient available volume in the net cage, meaning that large reductions in volume to reduce drag forces at high current velocities may be undesirable. Comparisons between model scale tests and numerical simulations reveal good agreements for the highest weight system loads tested. Decreasing the weight system loads decrease the accuracy of the numerical simulations. This may be caused by larger deformations of the net cage when the bottom loads are reduced resulting in a larger number of net panels with small angles of attack relative to the incident current. Predictions of forces for low angles of attack may be less accurate than for larger angles of attack while there is a possibility of increased flow velocity reduction (wake effect) and flow deflection. The cages were tested and simulated for flow velocities up to 1.25 m/s (full scale value). Measurements of the flow velocity in the middle of the net cages revealed a higher velocity reduction than predicted with theory, with the exception of the highest velocity.

Non-linear modelling of vortex induced lock-in effects on circular chimneys

The paper presents results of an extended study of the model developed earlier by the authors for across-wind response of tall circular chimneys to vortex shedding. A non-dimensional parameter,“fact” is used to suitably decrease the spectral bandwidth of the generalized across-wind load spectrum, implicitly accounting for an increase in load correlation. This paper discusses similarity between the parameter “fact” of authors’ model and the ratio of the aerodynamic damping coefficients, (ka/ka,0) in Vickery’s model, with respect to enhancement of correlation of force/response due to vortex shedding under lock-in condition. However, in Vickery’s model, as recommended in CICIND code, while the variation of (ka/ka,0) with increasing normalized amplitude follows a negative curvature, the corresponding variation of “fact” exhibits a positive curvature. Recent wind tunnel experimental results by Lupi et al., showed a positive curvature for the variation of (ka/ka,0) with increasing normalized amplitude. This lends support for authors’ observation. With a suitable scaling factor, an excellent agreement is found between the authors’ results and Lupi’s experimental results. The suggested method was applied to 27 full scale steel chimney data, referred in Lupi’s paper and the response predictions show a good comparison within ±20% limits with full scale values. The usefulness of the mass damping parameter, (2me(ρD2)η) for predicting the across-wind response is also discussed.

Complete dynamic similarity for sea trials and towing tank experiments by means of polymer drag reduction

We develop the approach to simulate the experiments with surface and underwater vehicles in towing tanks for Reynolds numbers Re, corresponding to sea trials, using discrete injection of polymer additives. The complete dynamic similarity between full-scale and tank tests is possible if both Froude number and Re are equal for a ship and its model. In traditional experiments, the first condition is only satisfied and the viscous and wave resistances are independently studied. The Toms effect is widely used in marine engineering, e.g., to reduce energy cost. In this work, it is applied quite differently. Re is higher and the skin friction coefficient cf is hence less for sea trials than for towing tanks. Injection of polymer additives allows decreasing cf on ship model to full-scale values, providing the complete similarity and reproducing sea trials in that way. We report the selected results of such novel approach that, in particular, include velocity profiles and cf for sea trial, towing tank and pipe experiments, plane boundary layer and 3D flow around propeller, rough and smooth surfaces. The data for full-scale and tank experiments agree well with each other.

Simplified Method for Calculating Active Earth Pressure Against Rigid Retaining Walls for Cohesive Backfill

The horizontal slice element method for calculating active earth pressure against rigid retaining walls has been extended to the cohesive backfill. The formula of the nonlinear distribution of active earth pressure is derived satisfying the reciprocal theorem of shear stress. According to the Mohr-Coulomb theory, the lateral active earth pressure coefficient can be determined. In order to check the accuracy of the proposed equation; the predictions from the equation are compared with both existing full-scale test results and values from other studies. The comparisons between calculated and measured values show that the proposed equations provide satisfactory results.

FOREIGN EXPERIENCE OF THE USE OF V-TYPE DISC CUTTERS IN TUNNELING AS A REFERENCE POINT FOR PROSPECTIVE STUDIES IN RUSSIA

Equipping of TBMs with rock cutting tools in the modern foreign practice of tunneling is based on the usage of CCS-type disc cutters. But there is also another type of tool for rock destruction when tunneling. It is a V-type disc cutter. As practice shows, in some situations it can provide greater work efficiency than a standard tool. Domestic research in this direction is mainly limited to the study of V-type tools of relatively small diameter for equipping roadheaders. Thus, this experience cannot be applied, if necessary, to the tunneling operations with TBM. Therefore, the studying of foreign experience on this issue is advisable. The paper analyzes studies conducted by foreign experts in the process of tunneling for various purposes in Turkey in the first decade of this century. These studies include the determination of a wide range of physical and technical properties of rocks, laboratory and field tests to determine the strength characteristics of the rock destruction process, comparison of laboratory, field and theoretical values of forces and energy performance of TBMs. As a result of the tests, it was found that the effectiveness of rock destruction is determined not only by their strength, but also by struc-tural and texture features. Differences were also observed when comparing laboratory experiments with field data, and comparing laboratory and full-scale force values on disc cutters in the process of rock destruction with theoretical values. In addition, the prospective areas of application of V-type disk cutters include the destruction of viscous non-abrasive rocks with a small amount of mineral inclusions or, with some reservations, the destruction of very hard and abrasive rocks. Not all conclusions made on the basis of the analysis performed coincide with the opinions of the authors of the initial studies, therefore, for a more complete understanding of the topic, it is recommended to read the literature (especially foreign literature) from the list of quoted sources.

Inviscid Scaling Laws of a Self-Propelled Pitching Airfoil

Inviscid computational results are presented on a self-propelled virtual body combined with an airfoil undergoing pitch oscillations about its leading edge. The scaling trends of the time-averaged thrust forces are shown to be predicted accurately by Garrick’s theory. However, the scaling of the time-averaged power for finite-amplitude motions is shown to deviate from the theory. Novel time-averaged power scalings are presented that account for a contribution from added-mass forces, from the large-amplitude separating shear layer at the trailing edge, and from the proximity of the trailing-edge vortex. Scaling laws for the self-propelled speed, efficiency, and cost of transport (CoT) are subsequently derived. Using these scaling relations, the self-propelled metrics can be predicted to within 5% of their full-scale values by using parameters known a priori. The relations may be used to drastically speed up the design phase of bioinspired propulsion systems by offering a direct link between design parameters and the expected CoT. The scaling relations also offer one of the first mechanistic rationales for the scaling of the energetics of self-propelled swimming. Specifically, the cost of transport is shown to scale predominately with the added mass power. This suggests that the CoT of organisms or vehicles using unsteady propulsion will scale with their mass as , which is indeed shown to be consistent with existing biological data.

The Effect of Propeller Scaling Methodology on the Performance Prediction

In common model testing practise, the measured values of the self propulsion test are split into the characteristics of the hull, the propeller and into the interaction factors. These coefficients are scaled separately to the respective full scale values and subsequently reassembled to give the power prediction. The accuracy of this power prediction depends inter alia on the accuracy of the measured values and the scaling procedure. An inherent problem of this approach is that it is virtually impossible to verify each single step, because of the complex nature of the underlying problem. In recent years the scaling of the open-water characteristics of propeller model tests attracted a renewed interest, fuelled by competitive tests, which became the norm due to requests of the customer. This paper shows the influence of different scaling procedures on the predicted power. The prediction is compared to the measured trials data and the quality of the prediction is judged. The procedures examined are the standard ITTC 1978 procedure plus derivatives of it, the Meyne method, the strip method developed by the Hamburgische Schiffbau-Versuchsanstalt (HSVA) and the β i -method by Helma.

Assessment of hydrodynamic characteristics of a full-scale ship at different draughts

Numerical and experimental assessment of resistance and propulsion characteristics for a handymax bulk carrier at full-scale is carried out within this paper. Reynolds Averaged Navier-Stokes equations and Volume of Fluid Method are utilized in numerical simulations of resistance, open water and self-propulsion tests for three load conditions at two speeds. Verification of the obtained numerical results is performed and numerical uncertainty is calculated. Also, comparison of four turbulence models for resistance, open water and self-propulsion tests is made. An extensive towing tank experiments are performed in Brodarski institute and the obtained results are extrapolated to full-scale values using five extrapolation methods. Furthermore, numerical results are validated by comparison with extrapolated values of total resistance, open water and propulsion characteristics. A detailed analysis of the results is provided, and advantages and disadvantages of extrapolation methods are highlighted. Also, the importance of utilizing CFD based on viscous flow in the improvement of reliability of extrapolation methods and in reducing the incremental resistance coefficient is shown. Finally, the advantages of utilizing CFD based on viscous flow for assessment of ship hydrodynamic characteristics at full-scale are presented.

Unsteady propulsion by an intermittent swimming gait

Inviscid computational results are presented on a self-propelled swimmer modelled as a virtual body combined with a two-dimensional hydrofoil pitching intermittently about its leading edge. Lighthill (Proc. R. Soc. Lond.B, vol. 179, 1971, pp. 125–138) originally proposed that this burst-and-coast behaviour can save fish energy during swimming by taking advantage of the viscous Bone–Lighthill boundary layer thinning mechanism. Here, an additional inviscid Garrick mechanism is discovered that allows swimmers to control the ratio of their added-mass thrust-producing forces to their circulatory drag-inducing forces by decreasing their duty cycle,$DC$, of locomotion. This mechanism can save intermittent swimmers as much as 60 % of the energy it takes to swim continuously at the same speed. The inviscid energy savings are shown to increase with increasing amplitude of motion, increase with decreasing Lighthill number,$Li$, and switch to an energetic cost above continuous swimming for sufficiently low$DC$. Intermittent swimmers are observed to shed four vortices per cycle that give rise to an asymmetric time-averaged jet structure with both momentum surplus and deficit branches. In addition, previous thrust and power scaling laws of continuous self-propelled swimming are further generalized to include intermittent swimming. The key is that by averaging the thrust and power coefficients over only the bursting period then the intermittent problem can be transformed into a continuous one. Furthermore, the intermittent thrust and power scaling relations are extended to predict the mean speed and cost of transport of swimmers. By tuning a few coefficients with a handful of simulations these self-propelled relations can become predictive. In the current study, the mean speed and cost of transport are predicted to within 3 % and 18 % of their full-scale values by using these relations.

Experimental investigation of correction factor for VIV amplitude of flexible bridges from an aeroelastic model and its 1:1 section model

Evaluation of the maximum amplitudes of vortex-induced vibrations (VIV) in suspension bridges is mainly relied upon section model wind tunnel tests of bridge decks. Extrapolation to prototype responses requires addition correction to take into account the differences both in structural mode shape and in spanwise correlation of excitation forces between the section model and the prototype. The paper presents the results of VIV amplitudes measured on an aeroelastic model and on its section model with the same size of cross-section. The aeroelastic model is a new, elastically multi-supported one which is capable of reproducing the closely-spaced vertical modes of a suspension bridge. The vortex-induced vibrations for a number of vertical modes were successfully measured from the aeroelastic model test in smooth flow. The spring-mounted section model having the same size of cross-section as the aeroelastic model was also tested in smooth flow at the same mass, damping ratio and vibration frequency. It is shown that both the VIV onset wind velocity and lock-in range for each mode of vibration are in good agreement between the aeroelastic model and the section model. The aeroelastic model consistently produces a roughly 30% higher maximum amplitude than the section model for the observed modes of vibration. It is confirmed that the combined three-dimensional (3D) effects due to mode shape and imperfect correlation of excitation forces amplify the VIV amplitudes and disregarding these effects may underestimate the VIV amplitudes for section model tests. A correction factor of 1.3 for the VIV amplitude of vertical modes in suspension bridges may be adopted for practical use when extrapolating the section-model results to their corresponding full-scale values.

Local modeling of the aerodynamic heating of the blunt body surface in subsonic high-enthalpy air flow. Theory and experiment on a high-frequency plasmatron

The concept of the local similarity of nonequilibrium boundary layers in high-enthalpy gas flows past blunt bodies is briefly described. The technical possibilities of the VGU-4 induction high-frequency plasmatron in modeling the aerodynamic heating of the hypothetical Pre-X (CNES) spacecraft in the vicinity of the stagnation point of a high-enthalpy air flow are presented. The engineering approach to quantitatively reproduce the thermochemical effect of a dissociated air flow on the vehicle surface in the high-heat region of the terrestrial entry trajectory is developed. In this approach the full-scale values of the total enthalpy, the stagnation pressure, and the velocity gradient at the stagnation point near the surface are reproduced in the experiment. The effective coefficients of O and N atom recombination on a silicone carbide (SiC) surface are determined under the conditions similar with those of the peak heating of the Pre-X vehicle surface in the vicinity of the flow stagnation point.

Sensor density or sensor sensitivity?

It is widely recognized that image quality can be improved by acquiring seismic data with long offsets, wide azimuths, low frequencies, and dense source and receiver sampling. To achieve this in an affordable way, we see a trend toward single-sensor recording in high-productivity land seismic surveys. Moving away from field arrays has a material effect on requirements for sensors and channels and for the way their performance is specified and displayed. While increased sampling density can compensate for the lack of sampling and noise reduction achieved by field arrays, there is a trade-off in the resultant sensitivity change of the sensor compared to the array and the preamplifier gain setting. Higher sensitivity geophones should be selected and lower preamplifier gain considered for single-sensor surveys. Two measures are introduced to help in finding a balance between adequate sampling and sensor/recorder channel performance at the acquisition design stage. The amplitude spectral density (ASD) expressed in ground-motion units is proposed as a frequency-dependent alternative for root-mean-square (rms) values to evaluate noise properties of the sensor/recorder channel combination. The operating range diagram (ORD) is adopted to offer a more meaningful dynamic-range measure than the instantaneous dynamic range by honoring the differing mathematical properties of signal and noise. The ORD compares full-scale rms values at a range of frequencies with narrowband noise values centered at the same frequencies.

Full-Scale Assessment of Pansharpening Through Polynomial Fitting of Multiscale Measurements

Pansharpening techniques aim at improving the spatial resolution of a multispectral data set (MS) by using a panchromatic image (Pan) acquired on the same scene with a greater spatial resolution and consequently a lower ground sample distance (GSD). Usually, a quantitative assessment of the fused products cannot be directly performed because of the lack of a reference MS data set with the same GSD of the Pan. A well-known solution is Wald's protocol: The original MS and Pan are spatially degraded, the reducing factor being the ratio between their GSDs. Pansharpening is then performed between the reduced MS and Pan data sets, and the fused products are compared with the original MS, which can be used as reference. In this protocol, fusion performances are assumed to be independent of the scale so that the results at the reduced scale are an estimation of those at the original resolution. This hypothesis can be more or less reliable, depending on the sensor and/or the scene content. The objective of this paper is to propose a new methodology to infer the unknown performances of a pansharpening method at full scale. For this purpose, multiple sets of fused images are computed at degraded scales by downsampling Pan and MS data sets by means of the sensor modulation transfer function. Multiscale quality/distortion measurements are fitted by linear and quadratic polynomials in order to extrapolate their full-scale values. Once the proposed protocol has been assessed in the presence of reference originals, the obtained results are extended to the case where the reference image is not available.

Development of an Analytical Model to Predict the Field Permeability of Asphalt Pavements

Measurement of the field permeability of asphalt pavement is affected by three-dimensional flow, saturation, and other field boundary conditions. Therefore, field permeability testing is generally avoided for compaction quality control, mix evaluation, and evaluation of moisture intrusion or damage of asphalt pavements. Instead, laboratory permeability is used for asphalt mix (compaction) evaluation. Because most transportation agencies and paving contractors collect field cores for compaction and mix quality evaluation, an analytical model to predict field permeability can be useful in the study of the hydraulic conductivity of field pavements. This study used an analytical model to determine the field permeability of asphalt pavement by using laboratory tests for permeability and permeable pores of cores. Permeability and the permeable porosity of two sizes of asphalt cores were determined in the laboratory with a falling head permeameter that was modified with a salt concentration–measuring meter. The parameters were then used in the analytical model to predict field permeability. The predicted values from the model were found to compare reasonably well with the full-scale field permeability values. The results of the analytical model were compared with the results from existing models, and the developed analytical model showed an improvement over the existing models. The model can be a useful tool in the study of the hydraulic behavior of asphalt.