Journal articles on the topic 'Curvilinear measurements'
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1
Pirk, Norbert, Mikhail Mastepanov, Frans-Jan W. Parmentier, Magnus Lund, Patrick Crill, and Torben R. Christensen. "Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations." Biogeosciences 13, no. 4 (February 18, 2016): 903–12. http://dx.doi.org/10.5194/bg-13-903-2016.
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Abstract. The closed chamber technique is widely used to measure the exchange of methane (CH4) and carbon dioxide (CO2) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured gas concentrations. Due to experimental uncertainties the simple linear regression model (first-order polynomial) is often applied, even though theoretical considerations of the technique suggest the application of other, curvilinear models. High-resolution automatic chamber systems which sample gas concentrations several hundred times per flux measurement make it possible to resolve the curvilinear behavior and study the information imposed by the natural variability of the temporal concentration changes. We used more than 50 000 such flux measurements of CH4 and CO2 from five field sites located in peat-forming wetlands ranging from 56 to 78° N to quantify the typical differences between flux estimates of different models. In addition, we aimed to assess the curvilinearity of the concentration time series and test the general applicability of curvilinear models. Despite significant episodic differences between the calculated flux estimates, the overall differences are generally found to be smaller than the local flux variability on the plot scale. The curvilinear behavior of the gas concentrations within the chamber is strongly influenced by wind-driven chamber leakage, and less so by changing gas concentration gradients in the soil during chamber closure. Such physical processes affect both gas species equally, which makes it possible to isolate biochemical processes affecting the gases differently, such as photosynthesis limitation by chamber headspace CO2 concentrations under high levels of incoming solar radiation. We assess the possibility to exploit this effect for a partitioning of the net CO2 flux into photosynthesis and ecosystem respiration as an example of how high-resolution automatic chamber measurements could be used for purposes beyond the estimation of the net gas flux. This shows that while linear and curvilinear calculation schemes can provide similar net fluxes, only curvilinear models open additional possibilities for high-resolution automatic chamber measurements.
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Hopkins, DL. "An evaluation of the Hennessy Grading Probe for measuring fat depth in beef carcasses." Australian Journal of Experimental Agriculture 29, no. 6 (1989): 781. http://dx.doi.org/10.1071/ea9890781.
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Fat depth at the P8 site on the rump was measured by the cut-and-measure (CM) technique and with the Hennessy Grading Probe (HGP) on 2501 beef carcasses at 1 abattoir over a 12-month period. CM measurements that differed by more than 1 mm between the right and left sides of the carcass were discarded. A subsequent data set of 1850 carcasses was randomly divided so that 2 models could be developed to assess the general validity of the relationship between the 2 methods of measurement. Analysis of measurements of the left side of the carcasses of these 2 subsamples showed the data were not normally distributed. Removal of outliers at the 95% confidence level and also measurements at both extremes of the data range improved the symmetry of the sets of data. From each adjusted data set, regression equations were developed to predict CM measurements from HGP measurements. Linear equations were adequate for predicting CM measurements from HGP measurements, and curvilinear analysis did not improve the predictions. Compared with the curvilinear equations, the linear equations resulted in smaller differences between the 2 data sets for the predicted CM measurements over a range of HGP measurements.
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Magdziak, Marek. "Selection of the Best Model of Distribution of Measurement Points in Contact Coordinate Measurements of Free-Form Surfaces of Products." Sensors 19, no. 24 (December 4, 2019): 5346. http://dx.doi.org/10.3390/s19245346.
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The article presents a new method for determining the distribution of measurement points, which can be used in the case of contact coordinate measurements of curvilinear surfaces of products. The developed method is based on multi-criteria decision analysis. In the case of the new method, the selection of the distribution of measurement points on free-form surfaces is carried out based on the analysis of five different criteria. The selection of the best model of the distribution of measurement points results from the accuracy of coordinate measurements, the time needed to complete measurement tasks, the number of measurement points, the accuracy of the substitute surface representing the measured free-form surface and the area where measurement points are located. The purpose of using the developed method of the distribution of measurement points is to increase the performance of coordinate measurements primarily by increasing the automation of strategy planning of measurements of curvilinear surfaces and improving the accuracy of measurements of free-form surfaces of products. The new method takes into account various aspects of coordinate measurements to determine the final model of the distribution of measurement points on measured surfaces of products, thereby increasing the probability of the proper determination (i.e., identifying the highest deviations of a product) of the location of measurement points on the surfaces of a measured object. The paper presents an example of the application of the created method, which concerns the selection of the best model of the distribution of measurement points on a selected free-form surface. This example is based on, among others, the results of experimental investigations, which were carried out by using the ACCURA II coordinate measuring machine equipped with the VAST XXT measuring probe and the Calypso measurement software. The results of investigations indicate a significant reduction in time of coordinate measurements of products when using the new method for determining the distribution of measurement points. However, shortening the time of coordinate measurements does not reduce their accuracy.
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Werner, Andrzej. "Evaluation of the degree of fitting of a curvilinear hole and stub machined on a CNC milling center." Mechanik 92, no. 12 (December 9, 2019): 781–83. http://dx.doi.org/10.17814/mechanik.2019.12.108.
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The method of evaluating the accuracy of fitting a curvilinear hole-stub pair is presented. The next stages of the process were presented, including: machining of elements, coordinate measurements of machined parts, analysis of measurement results. A method to improve the degree of fitting of the hole-stub pair is proposed.
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Magdziak, Marek. "A New Method of Distribution of Measurement Points on Curvilinear Surfaces of Products." Sensors 19, no. 12 (June 13, 2019): 2667. http://dx.doi.org/10.3390/s19122667.
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The article presents the method of selecting scanning lines along which coordinate measurements, performed by using, e.g., a coordinate measuring machine working in the single point probing mode, of free-form surfaces of measured workpieces may be conducted. Additionally, the proposed method supports the user of a coordinate measuring system during defining the number of measurement points distributed along selected scanning lines, thus deciding on the final distribution of measurement points on a measured surface of a product. The proposed method enables distributing measurement points in the parts of a measured product characterized by the worst quality of manufacturing. Moreover, the new method is very automated, therefore it affects the increase in the efficiency of coordinate measurements. The effect of using the new method is the non-uniform distribution of measurement points located on free-form surfaces. The presented algorithm takes into account the lengths of selected cross-sections of a measured curvilinear surface of an object, its geometrical complexity and the accuracy of the probe radius correction process. The decision regarding the number of measurement points is made on the basis of the accuracy analysis of the calculations of the corrected measurement points obtained during the probe radius correction process and the accuracy of the substitute model representing a measured curvilinear surface. Two methods of the correction process were used. The accuracy of the applied methods of the probe radius compensation process was estimated on the basis of the deviations calculated between corrected measurement points and scanning lines. The selection of scanning lines and the number of measurement points was realized by using the expert system based on the fuzzy logic. The paper presents the results of both simulation and experimental investigations. The numerical calculations were performed for two selected free-form surfaces. The verification of the developed algorithm was carried out during experimental investigations based on a measurement of a selected free-form surface. The conducted research was aimed at verifying the correctness of the distribution of measurement points generated using the proposed method. In the case of real measurements, measurement points should be located in the places of surfaces of products characterized by the largest deviations of manufacturing. The results of the conducted investigations confirm the usefulness of the developed algorithm for defining the distribution of measurement points on curvilinear surfaces in the coordinate measuring technique. Moreover, the way of implementation of the developed method of the distribution of measurement points in selected commercial measurement software is presented, thus enabling the use of the new method in the industry.
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Magdziak, Marek, and Dominika Ziaja. "Software Dedicated to Determining a Strategy of Coordinate Measurements." Materials Science Forum 957 (June 2019): 179–86. http://dx.doi.org/10.4028/www.scientific.net/msf.957.179.
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The paper presents the developed software dedicated to determining a measurement strategy of contact coordinate measurements conducted by using coordinate measuring machines. The created software enables to calculate locations of the scanning lines along free-form surfaces of measured workpieces. The presented program was developed by using the MATLAB software. The created program was tested based on the selected examples of curvilinear surfaces. Measurement points were located in the parts of surfaces characterized by the biggest form deviations resulting from machining processes. The calculated deviations were the results of simulations performed by using selected CAM software. The presented software increases the efficiency of measurement processes.
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Morianou, G. G., N. N. Kourgialas, G. P. Karatzas, and N. P. Nikolaidis. "River flow and sediment transport simulation based on a curvilinear and rectilinear grid modelling approach – a comparison study." Water Supply 17, no. 5 (March 14, 2017): 1325–34. http://dx.doi.org/10.2166/ws.2017.031.
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In the present work, a two-dimensional (2D) hydraulic model was used for the simulation of river flow and sediment transport in the downstream section of the Koiliaris River Basin in Crete, Greece, based on two different structured grids. Specifically, an important goal of the present study was the comparison of a curvilinear grid model with a rectilinear grid model. The MIKE 21C model has been developed to simulate 2D flows and morphological changes in rivers by using either an orthogonal curvilinear grid or a rectilinear grid. The MIKE 21C model comprises two parts: (a) the hydrodynamic part that is based on the Saint-Venant equations and (b) the morphological change part for the simulation of bank erosion and sediment transport. The difference between the curvilinear and the rectilinear grid is that the curvilinear grid lines follow the bank lines of the river, providing a better resolution of the flow near the boundaries. The water depth and sediment results obtained from the simulations for the two different grids were compared with field observations and a series of statistical indicators. It was concluded that the curvilinear grid model results were in better agreement with the field measurements.
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Pirk, N., M. Mastepanov, F. J. W. Parmentier, M. Lund, P. Crill, and T. R. Christensen. "Calculations of automatic chamber flux measurements of methane and carbon dioxide using short time series of concentrations." Biogeosciences Discussions 12, no. 17 (September 4, 2015): 14593–617. http://dx.doi.org/10.5194/bgd-12-14593-2015.
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Abstract. The closed chamber technique is widely used to measure the exchange of methane (CH4) and carbon dioxide (CO2) from terrestrial ecosystems. There is, however, large uncertainty about which model should be used to calculate the gas flux from the measured gas concentrations. Due to experimental uncertainties the robust linear regression model (first order polynomial) is often applied, even though theoretical considerations of the technique suggest the application of other, curvilinear models. High-resolution automatic chamber systems which sample gas concentrations several hundred times per flux measurement make it possible to resolve the curvilinear behavior and study the information imposed by the natural variability of the temporal concentration changes. We used more than 50 000 such flux measurements of CH4 and CO2 from five field sites located in peat forming wetlands to calculate fluxes with different models. The flux differences from independent linear estimates are generally found to be smaller than the local flux variability on the plot scale. The curvilinear behavior of the gas concentrations within the chamber is strongly influenced by wind driven chamber leakage, and less so by changing gas concentration gradients in the soil during chamber closure. Such physical processes affect both gas species equally, which makes it possible to isolate biochemical processes affecting the gases differently, such as photosynthesis limitation by chamber headspace CO2 concentrations under high levels of incoming solar radiation. We assess the possibility to exploit this effect for a partitioning of the net CO2 flux into photosynthesis and ecosystem respiration and argue that high-resolution automatic chamber measurements could be used for purposes beyond the estimation of the net gas flux.
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Toner, Mary Ann, Floyd W. Emanuel, and Donald Parker. "Relationship of Spectral Noise Levels to Psychophysical Scaling of Vowel Roughness." Journal of Speech, Language, and Hearing Research 33, no. 2 (June 1990): 238–44. http://dx.doi.org/10.1044/jshr.3302.238.
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Direct magnitude estimation (DME) and equal-appearing interval (EAI) ratings of perceived roughness and spectral noise level (SNL) measurements of isolated sustained vowel samples (/a/ and /i/) were obtained. The linear and curvilinear relationships between the resulting roughness ratings and SNL were then examined. In the present study, the comparison between the two models resulted in conflicting evidence regarding the model that best described the relationship between roughness ratings and SNL measurements. In all comparisons, however, a significant linear component was indicated. Additionally, when a significant curvilinear component was indicated, the difference between the lines and curves that were fit to the data was minimal. The present findings suggest, therefore, that a high degree of linearity exists between both DME and EAI roughness ratings and SNL.
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Werner, Andrzej. "Correction of machining deviations of 2D profiles described with NURBS curves." Mechanik 91, no. 8-9 (September 10, 2018): 716–18. http://dx.doi.org/10.17814/mechanik.2018.8-9.113.
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The method of correction of machining of curvilinear profiles is presented. This method is based on the use of coordinate measurements of the pre-manufactured object. The results of the measurements contain information about the observed machining deviations. These data are used in the reconstruction of the geometric model of the produced profile.
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Popowczak, Marek, Pavol Horička, Jaromir Šimonek, and Jarosław Domaradzki. "The Functional Form of the Relationship between Body Height, Body Mass Index and Change of Direction Speed, Agility in Elite Female Basketball and Handball Players." International Journal of Environmental Research and Public Health 19, no. 22 (November 15, 2022): 15038. http://dx.doi.org/10.3390/ijerph192215038.
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The aim of this study was to assess the functional form of the relationship between two anthropometric measurements—body height (BH) and body mass index (BMI)—and two motor abilities—change of direction speed (CODS) and agility (AG)—in female elite basketball and handball players. It was hypothesized that BH and BMI might be significantly associated with AG and CODS. Two scenarios of the Five-Time Shuttle Run to Gates test (planned and unplanned) were used to evaluate the CODS and AG. Two forms of models were built to assess functional forms of the relationships between CODS and AG vs. BH and BMI: simple linear regression and binomial curvilinear regression for each type of team sport. The results confirmed the relationships between both anthropometric measurements and motor abilities only in HB, whereas in BB only a significant relationship was noted between BH and AG. Moreover, two curvilinear functional forms of the relationship were identified: inverted L-shape and inverted U-shape. Therefore, it was concluded that the first form of function indicated an initially proportional relationship between anthropometric measurement and motor test results and plateau after reaching a certain value of the BH or BMI. Similarly, the second form of function indicated the peak value of the BH or BMI which is threshold for the value of the anthropometric measurement when a progressive effect in the functional feature occurs.
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Mack, Spencer, Tammy Bonilla, Jeryl D. English, Benjamin Cozad, and Sercan Akyalcin. "Accuracy of 3-dimensional curvilinear measurements on digital models with intraoral scanners." American Journal of Orthodontics and Dentofacial Orthopedics 152, no. 3 (September 2017): 420–25. http://dx.doi.org/10.1016/j.ajodo.2017.05.011.
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Almutairi, Fahad F., Rawan Abdeen, Jaber Alyami, and Salahaden R. Sultan. "Effect of Depth on Ultrasound Point Shear Wave Elastography in an Elasticity Phantom." Applied Sciences 12, no. 13 (June 21, 2022): 6295. http://dx.doi.org/10.3390/app12136295.
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Background: Phantom studies are widely used to assess variability in measurements. This study aimed to assess the reliability and accuracy of point Shear Wave elastography (pSWE) measurements of an elasticity phantom. Methods: Measurements were obtained by an experienced certified clinical sonographer at three different depth levels in kPa, using a curvilinear 5-1MHz transducer of the EPIQ7 ultrasound imaging system. Results: A total of 180 pSWE measurements were obtained at three different depth levels (three cm, five cm, and seven cm) of the phantom background. The mean CV of pSWE was low at all depths (3 cm: 8.8%; 5 cm: 7%; 7 cm: 7.2%). There was a significant difference between measurements at depths of 3 cm vs. 7 cm (MD: −0.85, 95% CI −1.5, −0.11, p = 0.024) and measurements at depths 5 cm vs. 7 cm (MD: −1.1, 95% CI −1.7, −0.47, p = 0.001). An overestimation of mean pSWE measurements at a depth of 7 cm was noted compared to the manufacturer’s value (2.7%, p = 0.006). Conclusions: Superficial phantom SWE measurements in this study had low variability compared to deep measurement. pSWE measurements at deep levels can be overestimated.
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McCormack, Gavin R., Christine Friedenreich, Lindsay McLaren, Melissa Potestio, Beverly Sandalack, and Ilona Csizmadi. "Interactions between Neighbourhood Urban Form and Socioeconomic Status and Their Associations with Anthropometric Measurements in Canadian Adults." Journal of Environmental and Public Health 2017 (2017): 1–10. http://dx.doi.org/10.1155/2017/5042614.
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Neighbourhood-level socioeconomic composition and built context are correlates of weight-related behaviours. We investigated the relations between objective measures of neighbourhood design and socioeconomic status (SES) and their interaction, in relation to self-reported waist circumference (WC), waist-to-hip ratio, and body mass index (BMI) in a sample of Canadian adults (n=851from 12 Calgary neighbourhoods). WC and BMI were higher among residents of disadvantaged neighbourhoods, independent of neighbourhood design (grid, warped grid, and curvilinear street patterns) and individual-level characteristics (sex, age, education, income, dog ownership, marital status, number of dependents, motor vehicle access, smoking, sleep, mental health, physical health, and past attempts to modify bodyweight). The association between neighbourhood-level SES and WC was modified by neighbourhood design; WC was higher in disadvantaged-curvilinear neighbourhoods and lower in advantaged-grid neighbourhoods. Policies making less obesogenic neighbourhoods affordable to low socioeconomic households and that improve the supportiveness for behaviours leading to healthy weight in low socioeconomic neighbourhoods are necessary.
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Faichney, G. J., and S. G. Gherardi. "Relationships between organic-matter digestibility, dry-matter intake and solute mean retention times in sheep given a ground and pelleted diet." Journal of Agricultural Science 106, no. 2 (April 1986): 219–22. http://dx.doi.org/10.1017/s0021859600063796.
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SUMMARYThe relationships between organic-matter digestibility (OMD), dry-matter intake (DMI) and the mean retention time (MRT) of unabsorbed solutes in the gastrointestinal tract were examined using six fistulated, cross-bred, castrate male sheep. Measurements were made on each sheep at two different DMIs within the range 28–81 g D.m./(day. kg0·75). There were negative, curvilinear relationships between MRTs (both rumen and total) and DMI and positive, curvilinear relationships between OMD and MRTs. As a consequence, there was a negative, rectilinear relationship between OMD and DMI. OMD declined by 0·022 when DMI increased from calculated maintenance to twice maintenance. The proportion of the total MRT accounted for by rumen MRT did not change significantly; the mean value was 0·364 ( ± S.e. 0·010).
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Kobayashi, Kent, and Guofan Liu. "Estimating Leaf Area of Macadamia and Coffee." HortScience 31, no. 4 (August 1996): 665a—665. http://dx.doi.org/10.21273/hortsci.31.4.665a.
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One hundred mature leaves of macadamia (Macadamia integrifolia) were selected from 10 trees in a commercial orchard in Papaikou on the island of Hawaii. Length (L), width (W), and area (A) of each leaf were taken. L and W were significantly correlated (r = 0.93), L and A (r = 0.98), W and A (r = 0.94), and (L × W) and A (r = 0.99). L and W showed curvilinear relationships with A. Seventy-five mature leaves of coffee (Coffea arabica `Guatemalan') were selected from five trees at the Waimanalo Expt. Station on the island of Oahu. Leaf L, W, and A were measured. L and W were significantly correlated (r = 0.72), L and A (r = 0.89), W and A (r = 0.93), and (L × W) and A (r = 0.98). L and W showed curvilinear relationships with A. For both macadamia and coffee, although using L × W as a term in linear equations resulted in higher adjusted R2s, the use of these equations would involve taking an additional measurement in the field. A quadratic equation using width (for coffee) or length (for macadamia) best described the relationship between these measurements and area and provide a quick method for estimating leaf area in the field.
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Magdziak, Marek. "The influence of a number of points on results of measurements of a turbine blade." Aircraft Engineering and Aerospace Technology 89, no. 6 (October 2, 2017): 953–59. http://dx.doi.org/10.1108/aeat-03-2016-0044.
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Purpose The purpose of this paper was to determine the influence of a number of measured points on results of measurements of turbine blades, which are the parts of aircraft engines. The selection of a number of points is the part of a measurement strategy in the coordinate measuring technique and determines the accuracy of measurements. Design/methodology/approach Numerical and experimental investigations were conducted. The measurements were simulated using different numbers of measured points. The simulated measurements were performed for the selected dispersion of measured points. The dispersion reflected the inaccuracy of a manufacturing process of the considered product and the uncertainty of measurements of curvilinear surfaces. To verify the accuracy of the numerical studies, experimental research was conducted. The real measurements were conducted using the selected coordinate measuring machine. Findings The gained results following the simulations can be very useful when selecting the appropriate number of measured points. The chosen number of points may be used during real measurements of turbine blades conducted on coordinate measuring machines. The results of numerical research indicate that there should be used the average radii of leading and trailing edges to increase the accuracy of measurements. The results of real coordinate measurements confirmed the results of simulation studies. Originality/value The main novelty of the paper is the presented methodology for determining the influence of measured points on results of measurements. The presented methodology helps the user of a coordinate measuring system select the appropriate measurement strategy of free-form surfaces applied in the aerospace industry.
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MARSDEN, OLIVIER, CHRISTOPHE BOGEY, and CHRISTOPHE BAILLY. "HIGH-ORDER CURVILINEAR SIMULATIONS OF FLOWS AROUND NON-CARTESIAN BODIES." Journal of Computational Acoustics 13, no. 04 (December 2005): 731–48. http://dx.doi.org/10.1142/s0218396x05002906.
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The current work describes the application of high-order numerical techniques to single or multiple overset curvilinear body-fitted grids, demonstrating the feasibility of direct computations of noise radiated by flows around complex non-Cartesian bodies. Flows of both physical and industrial interest can be investigated with this approach. We first rapidly describe the numerical techniques implemented in our curvilinear simulations. The explicit high-order differencing and filtering schemes are presented, as well as their application to the curvilinear Navier–Stokes equations. We then present brief results of various 2-D acoustic simulations. First the flow around a cylinder, and the associated acoustic field, are described. The diameter-based Reynolds number Re D = 150 is under the critical Reynolds number of the onset of 3-D phenomena in the vortex-shedding. Simulation results can thus be meaningfully compared to experimental measurements. A case of acoustic scattering is then examined. A non-compact monopolar source is placed half way between two differently sized cylinders. A complex diffraction pattern is created, and resulting RMS pressure data are compared to the analytical solution. Finally the noise generated by a low Reynolds number laminar flow around a NACA 0012 airfoil is presented.
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Seo, Ribin. "Entrepreneurial orientation and innovation performance: insights from Korean ventures." European Journal of Innovation Management 23, no. 4 (August 14, 2019): 675–95. http://dx.doi.org/10.1108/ejim-01-2019-0023.
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Purpose The purpose of this paper is to explore the curvilinear relationship between entrepreneurial orientation (EO) and innovation performance in ventures of Korea, where this topic has been unexplored. Design/methodology/approach This study used 1,837 ventures’ responses in a panel data of the 2015 Korea’s Venture Business Investigation Survey. The measurements of EO based on the Miller/Covin and Slevin scale were used from the survey. The author adopted and independently measured three different indicators of innovation performance: technology innovation, product innovation and sales growth. Findings The results of the regression analysis show the significant curvilinear relationships of EO with technology innovation and product innovation, while the relationship between EO and sales growth remains linear. The author also found that multiplicative EO construct explains the changes in R2 better than the summative EO construct for the improvement of innovations in technology and product. Originality/value This paper provides empirical evidence on the EO–innovation performance relationships from Korean ventures – an underexplored area of research. It also takes into account the curvilinear relationships of summative and multiplicative EO constructs with different performance indicators. Future research can benefit from the use of the multiplicative EO estimation and multiple performance indicators to capture a clearer picture of the causal relationships.
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Stevanovic, Zarko, Nikola Mirkov, Zana Stevanovic, and Andrijana Stojanovic. "Validation of atmospheric boundary layer turbulence model by on-site measurements." Thermal Science 14, no. 1 (2010): 199–207. http://dx.doi.org/10.2298/tsci1001199s.
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Modeling atmosperic boundary layer with standard linear models does not sufficiently reproduce wind conditions in complex terrain, especially on leeward sides of terrain slopes. More complex models, based on Reynolds averaged Navier-Stokes equations and two-equation k-? turbulence models for neutral conditions in atmospheric boundary layer, written in general curvilinear non-orthogonal co-ordinate system, have been evaluated. In order to quantify the differences and level of accuracy of different turbulence models, investigation has been performed using standard k-? model without additional production terms and k-? turbulence models with modified set of model coefficients. The sets of full conservation equations are numerically solved by computational fluid dynamics technique. Numerical calculations of turbulence models are compared to the reference experimental data of Askervein hill measurements.
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BARANOWSKI, MACIEJ. "On the role of social factors in the loss of phonemic distinctions." English Language and Linguistics 17, no. 2 (June 10, 2013): 271–95. http://dx.doi.org/10.1017/s1360674313000038.
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The article tests the generalisation of the curvilinear hypothesis and the tendency of females to lead linguistic change in vocalic mergers on the basis of two mergers currently in progress in Charleston, South Carolina: the low-back merger and thepin–penmerger. It is based on sociolinguistic interviews with 100 informants, aged 8–90, covering the socioeconomic spectrum of the city. The speech of 90 of the informants is analysed acoustically; it is supplemented with minimal-pair tests and word list reading. F1/F2 measurements and minimal-pair test results are subjected to a series of multiple linear regression analyses, with social class, gender, age and style as independent variables. While the low-back merger is a change from below showing a female lead and a curvilinear effect of social class, thepin–penmerger shows a decreasing monotonic relationship with social class and no female advantage. The difference is argued to be due to the two mergers being at different levels of social awareness.
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Mantusov, М. N., V. K. Moiseev, A. A. Sharov, E. G. Gromova, and S. G. Ryzhakov. "FORMING OF SHEET DETAILS WITH CURVILINEAR SIDES WITH ELASTOMER PRESSURE." Izvestiya of Samara Scientific Center of the Russian Academy of Sciences 23, no. 1 (2021): 55–59. http://dx.doi.org/10.37313/1990-5378-2021-23-1-55-59.
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In the article, the authors present a method of constrained bending of sheet parts with curvilinear sides by the elastic media. They describe the process of constrained bending and the scheme of the experiment. After the first transition, a part with thinning in the radius and high side springing is obtained. The second transition, on a low-height rigging, a wave of excess material is first formed in the radius zone, which settles on the contour of the mandrel with a set of thickness. The stages of forming a semi-finished product are given. The experiment showed the feasibility of constrained bending of curved sides, wall thickness measurements showed that the second transition results in a thickening of the part wall. Finite element modeling of a constrained bend is performed to study the effect of excess of the Board on the thickening in the bending zone. Numerical studies of deformation processes have been carried out. An example of a diagram of the part thickness change for various deformation stages as a result of numerical studies is given. Dependence of part height exceeding with loss of stability during shaping is established. Examples of defects - folds are given.
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Werner, Andrzej, and Małgorzata Poniatowska. "Increasing the accuracy of a curvilinear profile machining on the basis of coordinate measurements results." Mechanik, no. 11 (November 2016): 1634–35. http://dx.doi.org/10.17814/mechanik.2016.11.468.
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Wood, John C., Cathleen Enriquez, Nilesh Ghugre, J. Michael Tyzka, Susan Carson, Marvin D. Nelson, and Thomas D. Coates. "MRI R2 and R2* mapping accurately estimates hepatic iron concentration in transfusion-dependent thalassemia and sickle cell disease patients." Blood 106, no. 4 (August 15, 2005): 1460–65. http://dx.doi.org/10.1182/blood-2004-10-3982.
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Abstract Measurements of hepatic iron concentration (HIC) are important predictors of transfusional iron burden and long-term outcome in patients with transfusion-dependent anemias. The goal of this work was to develop a readily available, noninvasive method for clinical HIC measurement. The relaxation rates R2 (1/T2) and R2* (1/T2*) measured by magnetic resonance imaging (MRI) have different advantages for HIC estimation. This article compares noninvasive iron estimates using both optimized R2 and R2* methods in 102 patients with iron overload and 13 controls. In the iron-overloaded group, 22 patients had concurrent liver biopsy. R2 and R2* correlated closely with HIC (r2 ≥ .95) for HICs between 1.33 and 32.9 mg/g, but R2 had a curvilinear relationship to HIC. Of importance, the R2 calibration curve was similar to the curve generated by other researchers, despite significant differences in technique and instrumentation. Combined R2 and R2* measurements did not yield more accurate results than either alone. Both R2 and R2* can accurately measure hepatic iron concentration throughout the clinically relevant range of HIC with appropriate MRI acquisition techniques. (Blood. 2005;106:1460-1465)
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Aitken, RL, and PW Moody. "Interrelations between soil pH measurements in various electrolytes and soil solution pH in acidic soils." Soil Research 29, no. 4 (1991): 483. http://dx.doi.org/10.1071/sr9910483.
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Ninety soil samples (81 surface, 9 subsurface) were collected from eastern Queensland and soil pH (1:5 soi1:solution) was measured in each of deionized water (pH,), 0.01 M CaCl2, 0-002 M CaCl2 and 1 M KCl. Soil solution was extracted from each soil after incubation for 4 days at the 10 kPa matric suction moisture content, and pH (pHss) and electrical conductivity were measured. The objectives of this work were to investigate interrelationships between soil pH measurements in various electrolytes and soil solution pH in a suite of predominantly acidic soils. Although the relationships between pHw and pH measured in the other electrolytes could be described by linear regression, the fitting of quadratic equations improved the coefficients of determination, indicating the relationships were curvilinear. The majority of soils exhibited variable charge characteristics (CEC increases with soil pH) and the curvilinear trend is explained on this basis. At low pH, the difference between pH, and pH measured in an electrolyte will be small compared with the difference at higher pH values because, in general, at low pH, soils will be closer to their respective PZSE (pH at which electrolyte strength has no effect). Of the electrolytes used, pH measured in 0.002 M CaCl2 gave the closest approximation to pHs,. However, when soils with ionic strengths greater than 0.018 M were selected (predominantly cultivated surface soils), pH in 0.01 M CaCl2 gave the best approximation to pHss. For predicting pHss, the ionic strength of the electrolyte will need to be matched to that of the soils studied. For a suite of soils with a large range in soil solution ionic strength (as in this study), it is preferable to measure pHss directly.
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Shen, Luyu, Changgen Lu, Weiguo Wu, and Shifeng Xue. "A High-Order Numerical Method to Study Three-Dimensional Hydrodynamics in a Natural River." Advances in Applied Mathematics and Mechanics 7, no. 2 (March 23, 2015): 180–95. http://dx.doi.org/10.4208/aamm.2014.m605.
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AbstractA high-order numerical method for three-dimensional hydrodynamics is presented. The present method applies high-order compact schemes in space and a Runge-Kutta scheme in time to solve the Reynolds-averaged Navier-Stokes equations with the k-ε turbulence model in an orthogonal curvilinear coordinate system. In addition, a two-dimensional equation is derived from the depth-averaged momentum equations to predict the water level. The proposed method is first validated by its application to simulate flow in a 180° curved laboratory flume. It is found that the simulated results agree with measurements and are better than those from SIMPLEC algorithm. Then the method is applied to study three-dimensional hydrodynamics in a natural river, and the simulated results are in accordance with measurements.
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LI, Q., Y. L. HE, and Y. J. GAO. "IMPLEMENTATION OF FINITE-DIFFERENCE LATTICE BOLTZMANN METHOD ON GENERAL BODY-FITTED CURVILINEAR COORDINATES." International Journal of Modern Physics C 19, no. 10 (October 2008): 1581–95. http://dx.doi.org/10.1142/s0129183108013126.
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A finite-difference lattice Boltzmann (LB) algorithm is described on general body-fitted coordinate systems. An alternative treatment for the implicit collision term of the Boltzmann–Bhatnagar–Gross–Krook equation is used, which completely removes the implicitness of the numerical scheme through using the characteristic of collision invariants. LB simulations are carried out for a two-dimensional supersonic viscous flow past a circular cylinder and the natural convection heat transfer in a circular enclosure with an inner hexagonal cylinder for the first time. The pressure coefficient distribution along the surface of the circular cylinder and the Nusselt number in the natural convection obtained from the simulations agree well with previous experimental measurements and/or classical computational fluid dynamics simulations. Comparisons of detailed flow patterns with other studies are also satisfactory.
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Cheng, Lailiang, and Leslie H. Fuchigami. "The Relationship between Rubisco Activity and Photosynthesis in Apple Leaves with Different Nitrogen Content." HortScience 32, no. 3 (June 1997): 530E—531. http://dx.doi.org/10.21273/hortsci.32.3.530e.
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Based on the curvilinear relationship between carboxylation efficiency and leaf N in apple leaves, we hypothesized that deactivation of Rubisco accounts for the lack of response of photosynthesis to increasing leaf N under high N supply. A wide range of leaf N content (from 1.0 to 5.0 g·m–2) was achieved by fertigating bench-grafted Fuji/M26 apple trees for 6 weeks with different N concentrations using a modified Hoagland solution. Analysis of photosynthesis in response to intercellular CO2 under both 21% and 2% O2 indicated that photosynthesis at ambient CO2 was mainly determined by the activity of Rubisco. Measurements of Rubisco activity revealed that initial Rubisco activity increased with leaf N up to 3.0 g·m–2, then leveled off with further rise in leaf N, whereas total Rubisco activity increased linearly with increasing leaf N throughout the leaf N range. As a result, Rubisco activation state decreased with increasing leaf N. Photosynthesis at ambient CO2 and carboxylation efficiency were both linearly correlated with initial Rubisco activity, but showed curvilinear relationships with total Rubisco activity and leaf N. As leaf N increased, photosynthetic nitrogen use efficiency declined with decreasing Rubisco activation state.
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Prisk, G. Kim, Harold J. B. Guy, John B. West, and James W. Reed. "Validation of measurements of ventilation-to-perfusion ratio inequality in the lung from expired gas." Journal of Applied Physiology 94, no. 3 (March 1, 2003): 1186–92. http://dx.doi.org/10.1152/japplphysiol.00662.2002.
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The analysis of the gas in a single expirate has long been used to estimate the degree of ventilation-perfusion (V˙a/Q˙) inequality in the lung. To further validate this estimate, we examined three measures ofV˙a/Q˙ inhomogeneity calculated from a single full exhalation in nine anesthetized mongrel dogs under control conditions and after exposure to aerosolized methacholine. These measurements were then compared with arterial blood gases and with measurements of V˙a/Q˙ inhomogeneity obtained using the multiple inert gas elimination technique. The slope of the instantaneous respiratory exchange ratio (R slope) vs. expired volume was poorly correlated with independent measures, probably because of the curvilinear nature of the relationship due to continuing gas exchange. When R was converted to the intrabreathV˙a/Q˙ (iV˙/Q˙), the best index was the slope of iV˙/Q˙ vs. volume over phase III (iV˙/Q˙slope). This was strongly correlated with independent measures, especially those relating to inhomogeneity of perfusion. The correlations for iV˙/Q˙ slope and R slope considerably improved when only the first half of phase III was considered. We conclude that a useful noninvasive measurement ofV˙a/Q˙ inhomogeneity can be derived from the intrabreath respiratory exchange ratio.
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Burd, M., No author No author, and J. Craig. "The palmar metric: A novel radiographic assessment of the equine distal phalanx." Open Veterinary Journal 5, no. 2 (2014): 78. http://dx.doi.org/10.5455/ovj.2014.v4.i2.p78.
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Digital radiographs are often used to subjectively assess the equine digit. Recently, quantitative and objective radiographic measurements have been reported that give new insight into the form and function of the equine digit. We investigated a radio-dense curvilinear profile along the distal phalanx on lateral radiographs we term the Palmar Curve (PC) that we believe provides a measurement of the concavity of the distal phalanx of the horse. A second quantitative measurement, the Palmar Metric (PM) was defined as the percent area under the PC. We correlated the PM and age from 544 radiographs of the distal phalanx from the left and right front feet of various breed horses of known age, and 278 radiographs of the front feet of Quarter Horses. The PM was negatively correlated with age and decreased at a rate of 0.28 % per year for horses of various breeds and 0.33 % per year for Quarter Horses. Therefore, veterinarians should be aware of age related change in the concave, parietal solar aspect of the distal phalanx in the horse.
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Piotr Fundowicz, Hubert Sar, and Mateusz Brukalski. "Estimation of Wheels' Normal Reaction Forces of Automobile in Steady-State Curvilinear Motion." Communications - Scientific letters of the University of Zilina 23, no. 4 (August 27, 2021): B317—B324. http://dx.doi.org/10.26552/com.c.2021.4.b317-b324.
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Computer simulation seems to be one of the cheapest and relatively fast methods of investigating vehicle motion. Thereby, it may be important in the case of calculations for the reconstruction of traffic incidents. In particular, that may be important to answer the following question: How wheels' normal reaction forces differ during the cornering of a vehicle?
In this article, the authors presented how the normal reaction forces vary in the case of roll motion of a vehicle body. Suitable mathematical equations are presented. Furthermore, the measurements of the height of the centre of gravity were performed, which was necessary to obtain the normal reaction forces while vehicle body rolls. The authors decided to apply dimensionless coefficients, which represented the properties of a front and rear suspension. Additionally, dimensionless parameters were applied to consider the impact of asymmetrical distribution of vehicle load on normal reaction forces of wheels on a road surface.
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Bench, G., B. M. Clark, N. F. Mangelson, L. L. St. Clair, L. B. Rees, P. G. Grant, and J. R. Southon. "Accurate lifespan estimates cannot be obtained from 14C profiles in the crustose lichen Rhizocarpon geographicum (L.) DC." Lichenologist 33, no. 6 (November 2001): 539–42. http://dx.doi.org/10.1006/lich.2001.0353.
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AbstractRadial 14C/C profiles across three individuals of the crustose lichen Rhizocarpon geographicum (L.) DC. have been determined using accelerator mass spectrometry. These data were used to assess whether lifespan estimates can be determined in this species using 14C/C isotope ratio measurements. 14C/C profiles are relatively flat with Δ14C values (deviations from the modern radiocarbon standard) for the radial samples displaying a small spread ranging from 130 to 200 per mil. The data are consistent with carbon cycling based on growth patterns involving replacement and fusion of areoles within the thallus as well as or instead of cellular or molecular replacement. Consequently, lifespan estimates cannot be obtained from 14C/C measurements of this species and the Δ14C profiles provide no insights into whether the relationship between size and age is linear or curvilinear in this species.
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Suter, Larry E. "How international studies contributed to educational theory and methods through measurement of opportunity to learn mathematics." Research in Comparative and International Education 12, no. 2 (June 2017): 174–97. http://dx.doi.org/10.1177/1745499917711549.
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The international comparative studies in 1959 were conducted by International Association for the Evaluation of Educational Achievement (IEA) researchers who recognized that differences in student achievement measures in mathematics across countries could be caused by differences in curricula. The measurements of opportunity to learn (OTL) grew from a small effort in 1959 to a much larger efforts by 1995 to explain whether countries with high achievement were more likely to teach advanced mathematics. In general, the relationship of coverage of a mathematics topic was weakly related to the level of mathematics performance, but did have some effect on growth. This paper finds that differences in measurement methods of OTL across the studies greatly affected the outcome of the relationship. Recent Program for International Student Achievement (PISA) analyses indicate that the relationship between OTL and student achievement might be described as a curvilinear relationship. Countries with lower achievement are more likely to be affected by curriculum coverage than are high-performing countries.
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MONTGOMERY, MICHAEL T., VLADIMIR A. VLADIMIROV, and PETR V. DENISSENKO. "An experimental study on hurricane mesovortices." Journal of Fluid Mechanics 471 (November 5, 2002): 1–32. http://dx.doi.org/10.1017/s0022112002001647.
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Mesovortices in the eyewall region of a hurricane are intriguing elements of the hurricane engine. In-situ measurements of them are sparse, however, and our understanding of their overall role in the physics of a hurricane is incomplete. To further understand their dynamics an experimental apparatus using a homogeneous fluid (water) has been constructed to emulate the lower tropospheric flow of the hurricane eye/eyewall region.For experimental configurations possessing a central aspect ratio less than unity, a primary and secondary circulation similar to the in flow layer of an intense hurricane, and a similar radius-to-width ratio of the curvilinear shear layer bordering the eye and eyewall region, the flow supports two primary quasi-steady vortices and secondary intermittent vortices. The vortices form through Kelvin–Helmholtz instability of the curvilinear shear layer bordering the slowly upwelling fluid in the centre and the converging fluid from the periphery. The primary vortices are maintained by convergence of circulation from the periphery and merger of secondary vortices spawned along the shear layer.The horizontal flow field is measured using a particle image velocimeter. Despite the relatively strong secondary circulation through the parent vortex the horizontal flow is found to be approximately uniform in the direction parallel to the rotation axis. The peak tangential velocity is found to occur in the mesovortices and is roughly 50% greater than the parent vortex that supports them. The measurements provide insight into recent observations of excessive wind damage in landfalling storms and support the hypothesis that intense storms contain coherent vortex structures in the eyewall region with higher horizontal wind speeds locally than the parent hurricane.
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James, I. J., O. A. Osinowo, and T. O. Amoo. "Estimation of Liveweight from Chest Girth and Wither Height Measurements in West African Dwarf Goats." Nigerian Journal of Animal Production 34, no. 2 (January 9, 2021): 181–87. http://dx.doi.org/10.51791/njap.v34i2.1178.
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Linear and geometric regression equations were used to estimate liveweight of two hundred and eighty six semi-intensively managed West African Dwarf (WAD) goats from Chest girth (CG) and Wither height (WH) measurements. CG accounted for 52 and 58% variation in the liveweight of goats using linear and geometric equations respectively, thus showing a curvilinear relationship. WH accounted for 31% variation in liveweight of goats using both equations. CG measurement was found to be more reliable for estimating liveweight of WAD goats than WH measurement. Using linear regression equation, CG and WH estimated the liveweight of females better than males with average increases of 57% and 25% R' values respectively. Using geometric regression equation, CG and WH also estimated the liveweight of females better than males with average increases of 55% and 22% R' values respectively. In essence, CG and WH measurements estimated the liveweighi of does better than bucks using both regression equations. Generally, CG and WH better estimated the liveweight of goats that are greater or equal to 3 years old than goats that are greater than / year but less than 3 years old and goats that are less or equal to 1 year old using both regression equations. Even though, each of the geometric or linear regression equations may be used to estimate liveweight of WAD goats with a high degree of reliability in a specific class of animals, it would be simpler and less cumbersome to use the regression equation obtained from pooled data to estimate liveweight in all animals
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Zhang, Jialin. "3D Transonic Potential Flow Computation in an Axial-Flow Compressor Rotor by an Approximate Factorization Scheme." Journal of Engineering for Gas Turbines and Power 108, no. 1 (January 1, 1986): 112–17. http://dx.doi.org/10.1115/1.3239856.
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A conservative full-potential equation of 3D transonic flow in a turbomachine has been derived with the tensor method and expressed with respect to nonorthogonal curvilinear coordinates, and a fully implicit approximate factorization scheme to calculate the flow field has been developed in this paper. The new algorithm has been used to compute the 3D transonic flow field within an axial-flow single-stage compressor rotor tested by DFVLR. Comparisons between the computed flow field and the DFVLR data have been made. Results demonstrate that fast convergence can be achieved by the presented algorithm and that the agreement with the measurements obtained with an advanced laser velocimeter is quite good.
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Sert, Fatma Yelkenci, and Özgül Yılmaz Karaman. "An Investigation on the Effects of Architectural Features on Acoustical Environment of Historical Mosques." Acoustics 3, no. 3 (August 7, 2021): 559–80. http://dx.doi.org/10.3390/acoustics3030036.
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In the historical period, different mosques were built in the Anatolian side; the differences in size, typology and style were affected by the climate conditions, cultural and social aspects, availability of materials and the construction techniques of the region they were built in. The ceiling structure, which is the most influencing factor for mosque acoustics, is designed with either curvilinear elements or a flat ceiling for mosques. In the context of our case study, the eight historical mosques in Turkey, with different materials and types of ceiling structures, are investigated in terms of acoustical characteristics in the main prayer hall. Acoustical data are collected by measurements to reveal how the formal differences and material change in ceiling structures affect the acoustic environments of mosques with similar volume. Distribution of acoustical parameters and the suitability of the values obtained through measurements are compared to reflect the effect of architectural features on the acoustical characteristics of the prayer hall.
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Mahmud, T., J. S. Truelove, and T. F. Wall. "Flow Characteristics of Swirling Coaxial Jets From Divergent Nozzles." Journal of Fluids Engineering 109, no. 3 (September 1, 1987): 275–82. http://dx.doi.org/10.1115/1.3242661.
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The aerodynamic characteristics of free, swirling, coaxial jets issuing from an air model of a typical burner for pulverized bituminous coal have been studied. Detailed measurements of mean velocity and static pressure have been obtained in the region near the nozzle exit. The boundary of the reverse-flow zone has been mapped and the recirculated-mass flowrate measured in order to quantify the effects of velocity ratio and swirl in the primary and secondary jets. The influence of burner geometry (divergent-nozzle length and centre-line blockage) has also been studied. The type of flow pattern is found to depend upon the level of swirl in the primary and secondary jets. The recirculated-mass flowrate is predominantly influenced by secondary swirl. The measurements have been compared with predictions obtained by numerical solution of the governing conservation equations in orthogonal curvilinear co-ordinates. The general features of the flows are adequately predicted although discrepancies in detail seem to indicate deficiencies in the turbulence model.
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Iwaszenko, Sebastian, Jakub Munk, Stefan Baron, and Adam Smoliński. "New Method for Analysis of the Temporomandibular Joint Using Cone Beam Computed Tomography." Sensors 21, no. 9 (April 28, 2021): 3070. http://dx.doi.org/10.3390/s21093070.
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Modern dentistry commonly uses a variety of imaging methods to support diagnosis and treatment. Among them, cone beam computed tomography (CBCT) is particularly useful in presenting head structures, such as the temporomandibular joint (TMJ). The determination of the morphology of the joint is an important part of the diagnosis as well as the monitoring of the treatment results. It can be accomplished by measurement of the TMJ gap width at three selected places, taken at a specific cross-section. This study presents a new approach to these measurements. First, the CBCT images are denoised using curvilinear methods, and the volume of interest is determined. Then, the orientation of the vertical cross-section plane is computed based on segmented axial sections of the TMJ head. Finally, the cross-section plane is used to determine the standardized locations, at which the width of the gap between condyle and fossa is measured. The elaborated method was tested on selected TMJ CBCT scans with satisfactory results. The proposed solution lays the basis for the development of an autonomous method of TMJ index identification.
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Carratu, Michelle, and Roger J. Sauve. "EFFECTS OF WATER STRESS ON PHYTOPHTHORA-INFECTED RHODODENDRONS." HortScience 27, no. 6 (June 1992): 647b—647. http://dx.doi.org/10.21273/hortsci.27.6.647b.
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Phytophthora cinnamoni infected Rhododendrons subjected to moderate moisture levels had greater survival rates than at the wet or dry levels. We potted rooted cuttings of Rhododendron L. hybrid, “Lee's Dark Purple” in 3 liter containers using a mixture of 3 pine bark: 2 coarse builder's sand: 1 Canadian peat moss (by vol.) and infected them with P. cinnamoni. Tensiometers maintained the moisture levels of the treatments at 0, -5, -10, -15, and -20 kPa. After 90 days, measurements of the plants revealed virtually curvilinear results, with the highest survival rate, plant and root weights at -5 and -10 kPa. Investigation continues on susceptibility of Rhododendrons to P. cactorum, P. cryptogea, P. cinnamoni, and P. citrophthora under wet and dry conditions.
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Khaday, Samsiya, Kai-Way Li, Lu Peng, and Ching-Chung Chen. "Relationship between Friction Coefficient and Surface Roughness of Stone and Ceramic Floors." Coatings 11, no. 10 (October 15, 2021): 1254. http://dx.doi.org/10.3390/coatings11101254.
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Slips and falls are common occupational incidents worldwide. The friction on a floor surface is one of the critical environmental factors affecting the risk of a slip. In this research, we conducted friction measurements on stone and ceramic floor tiles under dry, wet, and water–detergent (WD) solution covered conditions using a horizontal pull slip meter (HPS). Our purposes were to quantify the slip resistance of commonly used stone and ceramic floors under different surface conditions and to validate the curvilinear relationship between the coefficient of friction (COF) and surface roughness of the floors proposed in the literature. The COF data were analyzed together with a surface profile parameter (Ra) of the floor samples. The results showed that the COFs of the stone floors were significantly (p < 0.0001) higher than those of the ceramic floors. All the floors under the dry conditions were slip resistant when adopting the ANSI 1264.2 criterion. Two and five ceramic floors were not slip resistant under the wet and WD solution covered conditions, respectively. Three polynomial regression equations were established to describe the relationship between the COF and Ra. The curvilinear functions of these models indicate that the three-zone (initial growth, steady-growth, and plateau) concept concerning the COF–Ra relationship in the literature was valid when static COF values measured using an HPS were adopted. In addition, the three-zone concept was valid not only on WD solution covered surfaces but also on dry and wet surfaces.
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Kiris, C., D. Kwak, S. Rogers, and I.-D. Chang. "Computational Approach for Probing the Flow Through Artificial Heart Devices." Journal of Biomechanical Engineering 119, no. 4 (November 1, 1997): 452–60. http://dx.doi.org/10.1115/1.2798293.
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Computational fluid dynamics (CFD) has become an indispensable part of aerospace research and design. The solution procedure for incompressible Navier–Stokes equations can be used for biofluid mechanics research. The computational approach provides detailed knowledge of the flowfield complementary to that obtained by experimental measurements. This paper illustrates the extension of CFD techniques to artificial heart flow simulation. Unsteady incompressible Navier–Stokes equations written in three-dimensional generalized curvilinear coordinates are solved iteratively at each physical time step until the incompressibility condition is satisfied. The solution method is based on the pseudocompressibility approach. It uses an implicit upwind-differencing scheme together with the Gauss–Seidel line-relaxation method. The efficiency and robustness of the time-accurate formulation of the numerical algorithm are tested by computing the flow through model geometries. A channel flow with a moving indentation is computed and validated by experimental measurements and other numerical solutions. In order to handle the geometric complexity and the moving boundary problems, a zonal method and an overlapped grid embedding scheme are employed, respectively. Steady-state solutions for the flow through a tilting-disk heart valve are compared with experimental measurements. Good agreement is obtained. Aided by experimental data, the flow through an entire Penn State artificial heart model is computed.
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Paliichuk, I. I., I. M. Kovbasiuk, O. B. Martsynkiv, and I. I. Vytvytskyi. "Forceful interaction of the casing string with the walls of a curvilinear well." Naukovyi Visnyk Natsionalnoho Hirnychoho Universytetu, no. 4 (August 30, 2022): 45–51. http://dx.doi.org/10.33271/nvngu/2022-4/045.
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Purpose. Developing a method for determining the axial forces and the walls reactions along a casing string, which bend it and make it follow a curved wellbore shape. Methodology. The casing string is represented as a long elastic rod in the curved well. An inhomogeneous system of four differential equations is developed to describe the rods deformations. It was reduced to a first-order differential equation with respect to axial force. Its solution was found by the Bernoulli method. The numerical integration of the differential equation is applied. Findings. The axial force distribution along the casing string was found, taking into account the well curvature and the friction, as well as the reaction forces of the well walls. A method of the tables numerical integration of the wells inclinometric measurements has been developed. The calculating formulas for the reaction forces, axial forces, bending moments and stresses acting in the casing pipes in the well deep are obtained. Originality. The solved problem takes into account the walls reaction and the friction forces that create longitudinal bend during the columns movement. The system of differential equations of equilibrium was supplemented by Eulers kinematic equation. The function of zenith angle, which is known due to the table of the directional survey data, was taken as the integration variable. The inverse problem is solved all unknown internal forces, also such the external distributed reaction, which causes the column to repeat the wells shape, was been determined by the angular deformations of casing string, which are given by the wells shape in the inclinometric table. Practical value. The developed method allows detecting the areas with a significant local increase in the wells curvature, which indicate their obstructed passability. This allows for accurate determination of depth intervals to increase the borehole diameter, which is necessary before lowering the column. According to the analysis results, it is possible to determine the parameters of the stress-strain state of the casing string, which can be used to predict its working capacity and operating life.
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D'Antonio, Peter, Luiz Augusto T. Ferraz Alvim, and Rinaldi P. Petrolli. "Boundary element method virtual goniometer to predict the diffusion and scattering coefficients." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A144. http://dx.doi.org/10.1121/10.0010917.
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The experimental measurement of the diffusion coefficient according to ISO 17497-2 is very time consuming and requires several sample periods to evaluate the effect of diffraction lobes, an anechoic or large reflection-free volume and far-field conditions. Wave-based BEM methods have predicted diffusion and correlation scattering coefficients very accurately [Hargreaves et al., J. Acoust. Soc. Am. 108 (4), 1710–1720 (2000)]. This presentation will describe a new Python Virtual Goniometer program, called VIRGO, which predicts the free-field and surface-mounted diffusion and correlation scattering coefficients for any shaped surface that can be successfully meshed from a three-dimensional file. The program accurately predicts the periodic diffraction grating lobes of a reference one-dimensional hemicylinder and a two-dimensional hemisphere, both in the free-field and surface mounted on a boundary. The diffusion coefficient and three-dimensional polar responses of additional number-theoretic and optimized profiled and curvilinear shapes will also be compared with scale model boundary-plane goniometer measurements. The results will verify that it is possible to precisely predict the diffusion and correlation scattering coefficients, without having to fabricate or 3D print scale models or full-scale samples.
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Eaton, M. D., D. L. Evans, D. R. Hodgson, and R. J. Rose. "Effect of treadmill incline and speed on metabolic rate during exercise in thoroughbred horses." Journal of Applied Physiology 79, no. 3 (September 1, 1995): 951–57. http://dx.doi.org/10.1152/jappl.1995.79.3.951.
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We examined the effect of treadmill speed and incline on O2 uptake (VO2), CO2 production, heart rate (HR), plasma lactate concentration, economy of locomotion, stride frequency, and stride length. A further aim was to examine the relationships between HR and VO2 and lactate and VO2 and whether these relationships vary with alterations in treadmill incline. The experiment was a latin square design, using five horses and five treadmill inclines (0, 2.5, 5.0, 7.5, and 10.0%). Fit Thoroughbred horses exercised for 4 min at 3 m/s at 0% slope, after which the treadmill was set to the allocated incline. Speeds tested ranged from 1 to 13 m/s. The relationships of VO2 and CO2 production with speed were curvilinear at 0 and 2.5% and linear at 5, 7.5, and 10% inclines. There was a linear relationship of HR and speed with a significant effect of incline. The plasma lactate concentration increased exponentially with speed, and there was a significant effect of incline. Stride length increased linearly and stride frequency increased in a curvilinear manner with speed but there was no effect of incline. There were linear relationships of HR with VO2 and HR with VO2 when expressed as percentage of maximum VO2 and maximum HR that were not affected by incline. The O2 cost of exercise on a 10% incline was approximately 2.5 times that for exercise on the flat. The strong relationship between the percentages of maximum HR and maximum VO2 indicates that over a wide range of exercise intensities the relative VO2 can be accurately predicted from measurements of HR.
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Jin, P., and R. J. Goldstein. "Local Mass/Heat Transfer on Turbine Blade Near-Tip Surfaces." Journal of Turbomachinery 125, no. 3 (July 1, 2003): 521–28. http://dx.doi.org/10.1115/1.1554410.
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Local mass transfer measurements on a simulated high-pressure turbine blade are conducted in a linear cascade with tip clearance, using a naphthalene sublimation technique. The effects of tip clearance (0.86–6.90% of chord) are investigated at an exit Reynolds number of 5.8×105 and a low turbulence intensity of 0.2%. The effects of the exit Reynolds number 4−7×105 and the turbulence intensity (0.2 and 12.0%) are also measured for the smallest tip clearance. The effect of tip clearance on the mass transfer on the pressure surface is limited to 10% of the blade height from the tip at smaller tip clearances. At the largest tip clearance high mass transfer rates are induced at 15% of curvilinear distance Sp/C by the strong acceleration of the fluid on the pressure side into the clearance. The effect of tip clearance on the mass transfer is not very evident on the suction surface for curvilinear distance of Ss/C<0.21. However, much higher mass transfer rates are caused downstream of Ss/C≈0.50 by the tip leakage vortex at the smallest tip clearance, while at the largest tip clearance, the average mass transfer is lower than that with zero tip clearance, probably because the strong leakage vortex pushes the passage vortex away from the suction surface. High mainstream turbulence level (12.0%) increases the local mass transfer rates on the pressure surface, while a higher mainstream Reynolds number generates higher local mass transfer rates on both near-tip surfaces.
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Chan, Nicholas R. "Phylogenetic variation in hind-limb bone scaling of flightless theropods." Paleobiology 43, no. 1 (November 24, 2016): 129–43. http://dx.doi.org/10.1017/pab.2016.32.
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AbstractThe robusticity of the weight-bearing limbs of large terrestrial animals is expected to increase at a more rapid rate than in their smaller relatives. This scaling has been hypothesized to allow large species to maintain stresses in the limb bones that are similar to those seen in smaller ones. Curvilinear scaling has previously been found in mammals and nonavian theropods but has not been demonstrated in birds. In this study, polynomial regressions of leg-bone length and circumference in terrestrial flightless birds were carried out to test for a relationship similar to that seen in nonavian theropods. Flightless birds exhibit curvilinear scaling, with the femora of large taxa becoming thicker relative to length at a greater rate than in smaller taxa. Evidence was found for nonlinear scaling in the leg bones of nonavian theropods. However, unlike in avians, there is also phylogenetic variation between taxonomic groups, with tyrannosaur leg bones in particular scaling differently than other groups. Phylogenetically corrected quadratic regressions and separate analyses of taxonomic groupings found little phylogenetic variation in flightless birds. It is suggested here that the nonlinear scaling seen in avian femora is due to the need to maintain the position of the knee under a more anterior center of mass, thereby restricting femoral length. The femur of nonavian theropods is not so constrained, with greater variability of the linear scaling relationships between clades. Phylogenetic variation in limb-bone scaling may broaden the errors for mass-predictive scaling equations based on limb-bone measurements of nonavian theropods.
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Buckley, Rachel F., Aaron P. Schultz, Trey Hedden, Kathryn V. Papp, Bernard J. Hanseeuw, Gad Marshall, Jorge Sepulcre, et al. "Functional network integrity presages cognitive decline in preclinical Alzheimer disease." Neurology 89, no. 1 (June 7, 2017): 29–37. http://dx.doi.org/10.1212/wnl.0000000000004059.
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Objective:To examine the utility of resting-state functional connectivity MRI (rs-fcMRI) measurements of network integrity as a predictor of future cognitive decline in preclinical Alzheimer disease (AD).Methods:A total of 237 clinically normal older adults (aged 63–90 years, Clinical Dementia Rating 0) underwent baseline β-amyloid (Aβ) imaging with Pittsburgh compound B PET and structural and rs-fcMRI. We identified 7 networks for analysis, including 4 cognitive networks (default, salience, dorsal attention, and frontoparietal control) and 3 noncognitive networks (primary visual, extrastriate visual, motor). Using linear and curvilinear mixed models, we used baseline connectivity in these networks to predict longitudinal changes in preclinical Alzheimer cognitive composite (PACC) performance, both alone and interacting with Aβ burden. Median neuropsychological follow-up was 3 years.Results:Baseline connectivity in the default, salience, and control networks predicted longitudinal PACC decline, unlike connectivity in the dorsal attention and all noncognitive networks. Default, salience, and control network connectivity was also synergistic with Aβ burden in predicting decline, with combined higher Aβ and lower connectivity predicting the steepest curvilinear decline in PACC performance.Conclusions:In clinically normal older adults, lower functional connectivity predicted more rapid decline in PACC scores over time, particularly when coupled with increased Aβ burden. Among examined networks, default, salience, and control networks were the strongest predictors of rate of change in PACC scores, with the inflection point of greatest decline beyond the fourth year of follow-up. These results suggest that rs-fcMRI may be a useful predictor of early, AD-related cognitive decline in clinical research settings.
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Leibholz, Jane. "The availability of lysine in diets for pigs: comparative methodology." British Journal of Nutrition 67, no. 3 (May 1992): 401–10. http://dx.doi.org/10.1079/bjn19920045.
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Four experiments were conducted to compare different methods for estimating the availability of lysine in protein feeds. The same feeds were used in all experiments. In the first experiment the apparent digestibility of lysine to the ileum of growing pigs was found to be 0.92, 0.69, 0.73, 0.85, 0.84 and 0.97 for soya-bean meal, cottonseed meal 1, cottonseed meal 2, meat meal, sunflower meal and skim milk respectively. In the second experiment the utilization of lysine (relative to free lysine) for weight gain, as measured in weaner pigs, was found to be 0.68, 0.73, 0.81, 0.86 and 1.00 for cottonseed meal 1, cottonseed meal 2, meat meal, sunflower meal and skim milk respectively. In Expt 3 diets were formulated to contain soya-bean meal, sunflower meal or cottonseed meal 2 with the same available lysine content from the measurements made in Expts 1 and 2. The feed conversion ratios of weaner pigs given these diets were similar for the three sources of protein when the values were adjusted for the differences in digestible dry matter intake. In the fourth experiment isoenergetic and isonitrogenous diets were formulated with increasing amounts of lysine from synthetic lysine or cottonseed meal 2. The diets were given to weaner pigs and resulted in a curvilinear response to lysine particularly for the cottonseed meal, so that the availability of lysine in cottonseed meal was similar to that of synthetic lysine at low lysine intakes and much lower than synthetic lysine at higher lysine intakes. Possible reasons for the curvilinear responses are discussed.
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Nelson, Monica, Soomi Lee, Tammy Allen, Orfeu Buxton, David Almeida, and Ross Andel. "GOLDILOCKS AT WORK: JUST THE RIGHT AMOUNT OF JOB DEMANDS MAY BE NEEDED FOR YOUR SLEEP HEALTH." Innovation in Aging 6, Supplement_1 (November 1, 2022): 655–56. http://dx.doi.org/10.1093/geroni/igac059.2419.
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Abstract Objectives It has been reported that job demands affect sleep, but how different levels of job demands affect sleep remains unclear. We examined whether curvilinear relationships exist between job demands and multiple sleep health outcomes. Design: Cross-sectional analyses with linear and quadratic effects, using self-administered survey data. Setting: A national sample of U.S. adults. Participants: Workers from Midlife in the United States Study (MIDUS2; n=2,927). Measurements: The Job Content Questionnaire assessed overall and five specific aspects of job demands (intensity, role conflict, work overload, time pressure, and interruptions). Habitual sleep health patterns across five dimensions (regularity, satisfaction/quality, daytime alertness, efficiency, and duration) were assessed. Age, sex, race/ethnicity, marital/partnered status, education, job tenure, work hours, body mass index, smoking status, and study sample were covariates. Results There were significant linear and quadratic relationships between job demands and sleep outcomes. Specifically, the linear effects indicated that higher job demands were associated with degraded sleep health, such as shorter duration, greater irregularity, greater inefficiency, and more dissatisfaction. The quadratic effects, however, indicated that the rate of degrade was decelerated in terms of sleep regularity and efficiency, such that these sleep outcomes were best with moderate levels of job demands. These effects were found for overall job demands as well as specific aspects of job demands. Stratified analyses further revealed that these curvilinear associations were mainly driven by participants with low job control. Conclusions Moderate levels of job demands, especially if combined with adequate job control, are related to better sleep health.