Academic literature on the topic 'Curvilinear measurements'
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Journal articles on the topic "Curvilinear measurements"
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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.
Full textAbstract:
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.
Full textAbstract:
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.
Dissertations / Theses on the topic "Curvilinear measurements"
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Naser-ud-Din, Shazia. "Analysis and correlation study of human masseter muscle with EMG, ultrasonography & 3D imaging." Thesis, 2009. http://hdl.handle.net/2440/63322.
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Form and function are inextricably intertwined in orthodontics. Our understanding of the hard tissue relationship has been comprehensive, with extensive clinical trials both cross sectional and longitudinal over the past several decades. The majority of studies have used standardized cephalograms that reflect our current concepts. However, the same cannot be stated for soft tissues and, more specifically, the muscles that envelope the skeletal bases.
The aim of the current study was to objectively evaluate the masseter muscle – one of the key elevator muscles in the human masticatory system with innovative diagnostic tools like electromyography (EMG), ultrasonography (US) and 3-D imaging (Mona Lisa®). Standard lateral cephalometrics were used as the gold standard for measuring the vertical facial dimensions and correlating the findings to the above mentioned modalities. This extensive study comprised three major components and involved subjects from the same cohort.
Firstly, the masseter muscle spindle reflexes were studied in dynamic chewing and the responses recorded with EMG in 28 human subjects. These were then analysed and correlated to the vertical facial proportion from standardized lateral cephalograms. Although substantial work has been done to evaluate the various trigeminal reflexes¹⁻³, limited research has investigated the reflexes from the muscle spindles in different facial proportions⁴. This is primarily due to the inherent complexity of the neurophysiology compounded by noise within the experimental models. Most often the method used to elicit a muscle spindle reflex in the human jaw involves a brief mechanical depression of the mandible, either by use of a tendon hammer or, if a more controlled stimulus is required, a computer-controlled stretching device⁵⁻⁷. In the current study, a sophisticated apparatus was utilized to deliver precise profile stimulus at predetermined intervals. Significant correlations were observed between the muscle spindle response and selected vertical proportions.
The second phase of study was to utilize US for measuring masseter muscle dimensions in the same cohort and once again correlate the various dimensions of the masseter muscle to the facial proportions generated by the lateral cephalometrics. US has been studied in dentistry for over four decades and it has been established as a safe, non-invasive, comfortable and cost-effective diagnostic implement. Also, US produces high resolution images of soft tissues more readily than MRI and CT scans⁸. Among the limitations for US there is the concern about
reproducibility and standardization particularly between operators. Hence, it is advisable to have a single operator for data collection in order to preclude interexaminer variability. Future use of US in dentistry will be favoured especially where
periodic evaluation is needed and there are concerns about radiation.
Finally, for a more holistic assessment, 3D optical scanning was used in the same sample cohort to analyse and correlate masseter muscle dimensions to vertical and transverse facial proportions. Regression equations were generated, albeit from the convenience sample, to explore a mathematical model for deriving variables of
interest rather than physically conducting the individual measurements, particularly if that required radiation. Current work shows strong correlations between lateral cephalometric and 3D imaging variables, but relatively weak associations with the ultrasonography. The findings from this study support the use of predictive equations from 3D imaging for lateral cephalometric variables but larger scale studies are required to confirm reproducibility. Moreover, curvilinear measurements from 3D images were significantly different (p < 0.0001) to the linear and should be adopted for more meaningful representation of the soft tissues.
These findings are relevant to facial form and function assessment which is used in orthodontic diagnosis and treatment planning; in particular, orthodontic functional appliance therapy. Analyses of the face can be carried out with a myriad of cephalometric packages; however, the role of the elevator muscles is often overlooked and their contribution to changes and/or characteristics that could benefit the orthodontic treatment is not fully appreciated. Thus, the assessment not only of anatomical but also physiological variations in the masseter muscles is important in the management of different facial patterns. The above tools provide a means to evaluate muscle functions which would be of particular interest in growing children and where functional orthopaedic appliances utilize forces from the muscles of mastication. Furthermore, periodic evaluation of such cases is generally desirable and needs to be safe, radiation free and cost-effective.Thesis (Ph.D.) -- University of Adelaide, School of Dentistry, 2009
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"Analysis, Design and Measurements of Flat and Curved Circularly Symmetric High Impedance Surfaces for Curvilinear Antenna Applications." Doctoral diss., 2018. http://hdl.handle.net/2286/R.I.50566.
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abstract: In this dissertation a new wideband circular HIS is proposed. The circular periodicity made it possible to illuminate the surface with a cylindrical TEMz wave and; a novel technique is utilized to make it wideband. Two models are developed to analyze the
reflection characteristics of the proposed HIS.
The circularly symmetric high impedance surface is used as a ground plane for the design of a low-profile loop and spiral radiating elements. It is shown that a HIS with circular periodicity provides a wider operational bandwidth for curvilinear radiating elements such, such as loops and spirals, compared to canonical rectangular HISs.
It is also observed that, with the aid of a circular HIS ground plane the gain of a loop and a spiral increases compared to when a perfect magnetic conductor (PMC) or rectangular HIS is used as a ground plane. The circular HIS was fabricated and the loop and spiral elements were placed individually in close proximity to it.
Also, due to the growing demand for low-radar signature (RCS) antennas for advanced airborne vehicles, curved and flexible HIS ground planes, which meet both the aerodynamic and low RCS requirements, have recently become popular candidates within the antenna and microwave technology. This encouraged us, to propose a spherical HIS where a 2-D curvature is introduced to the previously designed flat HIS.
The major problem associated with spherical HIS is the impact of the curvature on its reflection properties. After characterization of the flat circular HIS, which is addressed in the first part of this dissertation, a spherical curvature is introduced to the flat circular HIS and its impact on the reflection properties was examined when it was illuminated with the same cylindrical TEMz wave. The same technique, as for the flat HIS ground plane, is utilized to make the spherical HIS wideband. A loop and spiral element were placed in the vicinity of the curved HIS and their performanceswere investigated. The HISs were also fabricated and measurements were conducted to verify the simulations. An excellent agreement was observed.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2018
Books on the topic "Curvilinear measurements"
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United States. National Ocean Service. Coastal and Estuarine Oceanography Branch, ed. Orthogonal curvilinear grid generation [for Tampa Bay]. [Silver Spring, Md.]: U.S. Dept. of Commerce, National Oceanic and Atmospheric Administration, National Ocean Service, Office of Ocean and Earth Sciences, Marine Analysis and Interpretation Division, Coastal and Estuarine Oceanography Branch, 1995.
Find full textBook chapters on the topic "Curvilinear measurements"
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Styner, Martin, Thomas Coradi, and Guido Gerig. "Brain Morphometry by Distance Measurement in a Non-Euclidean, Curvilinear Space." In Lecture Notes in Computer Science, 364–69. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-48714-x_30.
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Streekstra, G. J., A. W. M. Smeulders, and R. van den Boomgaard. "Tracing of Curvilinear Structures in 3D Images with Single Scale Diameter Measurement." In Scale-Space Theories in Computer Vision, 501–6. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/3-540-48236-9_50.
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Streekstra, G. J., R. van den Boomgaard, and A. W. M. Smeulders. "Scale Dependent Differential Geometry for the Measurement of Center Line and Diameter in 3D Curvilinear Structures." In Computer Vision - ECCV 2000, 856–70. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/3-540-45054-8_56.
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Andrade-Valbuena, Nelson A., and Gonzalo R. Llanos-Herrera. "Why Are There Discrepancies in the Results of Entrepreneurial Orientation and Its Impact on a Firm's Performance?" In Practice, Progress, and Proficiency in Sustainability, 315–34. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-9301-1.ch017.
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Entrepreneurial orientation (EO) and its relationship to a firm's performance is a topic of substantial interest among scholars in different contexts. To date, however, literature on the subject has reported conflicting results and inconclusive evidence in studies relating entrepreneurial orientation to a firm's performance. In this sense, the authors have reviewed the literature and found that diverse opinions regarding definitions, scales of measurement and modeling of the construct, and its dimensions have led to conflicts within empirical research. They have also reviewed studies that have highlighted curvilinear relationships between EO and performance. This summary of issues highlighted in previous reviews serves as a guideline when addressing research on EO, contributing to the general discussion in strategic entrepreneurship literature about this important subject.
Conference papers on the topic "Curvilinear measurements"
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Kumar, Surya, and Andallib Tariq. "ESTIMATION OF TRANSIENT CONTACT HEAT TRANSFER BETWEEN CURVILINEAR SURFACES BY INFRARED THERMOGRAPHY MEASUREMENTS." In Proceedings of the 24th National and 2nd International ISHMT-ASTFE Heat and Mass Transfer Conference (IHMTC-2017). Connecticut: Begellhouse, 2018. http://dx.doi.org/10.1615/ihmtc-2017.680.
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Gal, Alicia M., Travis Douglas, Adrian D. C. Chan, and Dean C. Hay. "Potential for autonomous linear, curvilinear, and phase detection in natural context para skating using IMU sledge motion data." In 2020 IEEE International Symposium on Medical Measurements and Applications (MeMeA). IEEE, 2020. http://dx.doi.org/10.1109/memea49120.2020.9137225.
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HOSODA, TAKASHI, NOBUHISA NAGATA, ICHIRO KIMURA, KOJI MICHIBATA, and MICHIAKI IWATA. "A DEPTH AVERAGED MODEL OF OPEN CHANNEL FLOWS WITH LAG BETWEEN MAIN FLOWS AND SECONDARY CURRENTS IN A GENERALIZED CURVILINEAR COORDINATE SYSTEM." In Proceedings of the 8th International Symposium on Flow Modeling and Turbulence Measurements. WORLD SCIENTIFIC, 2002. http://dx.doi.org/10.1142/9789812777591_0007.
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Borazjani, Iman, Liang Ge, Fotis Sotiropoulos, Lakshmi Prasad Dasi, and Ajit Yogonathan. "Fluid-Structure Interaction in Bi-Leaflet Mechanical Heart Valves." In ASME 2007 2nd Frontiers in Biomedical Devices Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/biomed2007-38074.
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In this work we focus on the fluid-structure interaction (FSI) problem of a St. Jude Regent 23mm bi-leaflet mechanical heart valve (BMHV) implanted in modeled straight aorta geometry with a simplified sinus. A FSI solver based on a recently developed curvilinear grid/immersed boundary method fluid flow solver is developed. The current numerical simulation focuses on the acceleration phase within the cardiac cycle when the leaflets are opening following the incoming flow. The simulated results are compared with experimental data with regard to the leaflet kinematics as well as valve induced wake vortical structures and excellent agreement between the simulation and measurements is reported.
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Jin, P., and R. J. Goldstein. "Local Mass/Heat Transfer on Turbine Blade Near-Tip Surfaces." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30556.
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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 atthe 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. A 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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Gran, Inge R., M. C. Melaaen, and F. Magnussen. "Numerical Simulation of Fluid Flow and Combustion in Gas Turbine Combustors." In ASME 1993 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1993. http://dx.doi.org/10.1115/93-gt-166.
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The finite-volume approach together with body-fitted curvilinear non-orthogonal coordinates and a non-staggered grid arrangement is used for investigating turbulent reacting flows inside gas turbine combustion chambers. The computational grids are generated by solving elliptic differential equations, permitting an accurate description of the complex geometry of commercial gas turbine combustors. Different combustion models are briefly discussed with a view to their suitability for practical combustor predictions. The k-ε model and the Eddy Dissipation Concept are selected to account for the turbulent combustion in the present study. The governing equations and coordinate transformations needed to derive the discretized equations are reviewed. One isothermal and two combusting flow fields are calculated. The calculations are in reasonable agreement with measurements, but the results should be improved by grid refinement and by using a better turbulence model.
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Prasanna, D., and K. Aung. "Numerical Solutions of Single and Multiple Laminar Jets." In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77079.
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Modern power plants discharge approximately 1.5 to 2kWhr of waste heat for every kWhr of electrical energy produced. Modern power plants discharge approximately 1.5 to 2kWhr of waste heat for every kWhr of electrical energy produced. Usually this heat is discharged to an adjacent water body which increases the water temperature near the outfall. In order to assess the ecological consequences of waste heat discharge one must first know the physical changes (temperature, velocity, salinity) induced by these discharges. It is with this later aspect, prediction of physical properties, that the current work is primarily concerned. Existing theoretical work on axisymmetric buoyant jets is confined to integral techniques developed by Morton in the early 1950’s. From these techniques only centerline velocities and temperatures can be calculated. Experimental data for this type of flow are essentially confined to centerline temperature measurements except for pure jet or plume data which constitute the extremes for a buoyant jet. The present work addresses the problem of developing a theoretical model for an axisymmetric laminar buoyant jet. The governing equations for an axisymmetric buoyant jet in rectangular co-ordinates are transformed into an orthogonal curvilinear co-ordinate system which moves along the length of the jet axis. The complete partial differential equations governing steady, incompressible laminar flow are solved in the new curvilinear co-ordinates using finite-difference techniques. This method is applicable to a much wider range of jet flows issued at arbitrary angles into quiescent or flowing ambience. This method is also applied to the case for multiple jets spaced by a finite distance apart. Results for the momentum jet, axial and radial distribution of velocity and temperature, show good agreement with published data.
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Peterson, Michael “Mick”, and Miao Sun. "Stochastic Properties of Anisotropic Materials." In ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/nde-25813.
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Abstract Extensive research has been directed toward the development of methods for the optimal recovery of elastic properties from ultrasonic measurements. For a number of applications both the elastic and damping characteristics of the materials are required in design. The use of the optimal recovery does present challenges when applied to either man-made or natural anisotropic materials. In many cases manufacturing variability results in a need for a statistical description of the elastic and damping properties. In addition, errors in material lay-up or growth patterns may result in mis-orientation of the principle materials axes with respect to the geometrical axes. In this work, an examples is shown that demonstrates the recovery of the elastic properties of a natural material when stochastic properties are required. Statistical descriptions of the materials properties are obtained for wood of two different types of material. Results are shown assuming a nominally orthotropic orientation, although the existence of curvilinear coordinates is acknowledged.
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Martinez-Botas, R. F., K. R. Pullen, and F. Shi. "Numerical Calculations of a Turbine Volute Using a 3-D Navier-Stokes Solver." In ASME 1996 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/96-gt-066.
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The turbine volute is a complex flow device, about which a few papers on both measurements and CFD predictions have appeared. The main reasons for the difficulties being the complicated geometry which hinders measurements to be taken by both intrusive and non-intrusive techniques, and makes the numerical predictions difficult. In this paper, the complex three-dimensional flow through a turbine volute with non-symmetric circular cross-section is studied by using a 3-D Navier-Stokes solver which has been developed by the authors. In this solver, the fully 3-D Reynolds averaged N-S equations coupled with high Reynolds number k-ε turbulence model together with the wall function under arbitrary curvilinear coordinate system are solved. The Semi-Implicit Method for Pressure-Linked Equations (SIMPLEC algorithm) with the non-staggered grid arrangement is used. In order to eliminate the decoupling between the velocity and pressure under non-staggered grid system, the physical covariant velocity component is selected as dependent variable in momentum equations and a momentum interpolation approach is employed. The validity of the free-vortex assumption is reviewed. The computation results are compared with a set of experiments performed previously by one of the authors. The flow features in the volute are discussed.
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Marko, J. R., and D. B. Fissel. "Marine Ice Profiling: Future Directions." In SNAME 7th International Conference and Exhibition on Performance of Ships and Structures in Ice. SNAME, 2006. http://dx.doi.org/10.5957/icetech-2006-166.
Full textAbstract:
Upward-looking sonars moored on the sea floor have contributed to our qualitative and quantitative understandings of ocean ice covers by enabling quasi-continuous measurements of ice draft along curvilinear tracks to accuracies as great as 0.05 m. The capabilities of ASL’s own IPS4 instrument to acquire and store such data has been demonstrated in well over 100 deployments in polar and sub-polar ice-infested regions. Data obtained from these deployments has providing ice property and characterization information for platform and operations design, planning, navigation support and for scientific ice and climate studies. Results obtained with recent use of the IPS4 and a sister instrument specialized to shallow water applications have motivated both the development of new deployment methodologies and suggested applications additional to simple ice draft measurements. Particular potential uses such as detecting unconsolidated ice content in lower portions of ice keels as well as the prevalence of loose and/or frazil ice under ice covers and in shallow water areas are discussed. Perceived future needs in both conventional draft profiling and in these and other new applications are used to guide developing requirements for a new generation of IPS instrumentation offering new performance capabilities and additional user-specific configurability. ASL’s vision of this instrumentation and progress toward prototype construction is described.