Готові списки джерел за темами / Dimensional and geometrical precision

Зміст

Статті в журналах
Дисертації
Книги
Частини книг
Тези доповідей конференцій
Звіти організацій

Добірка наукової літератури з теми "Dimensional and geometrical precision"

Автор: Grafiati

Опубліковано: 11 березня 2023

Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями

Оберіть тип джерела:

Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Dimensional and geometrical precision".

Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.

Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.

Статті в журналах з теми "Dimensional and geometrical precision"

Liu, Junfeng, Yuqian Zhao, Tao Lai, Fei Li, and Kexian Liu. "Identification of Geometrical Error on Multi-Axis Machine Tools Based on a Laser Tracker." Journal of Physics: Conference Series 2185, no. 1 (January 1, 2022): 012008. http://dx.doi.org/10.1088/1742-6596/2185/1/012008.

Повний текст джерела

Анотація:

Abstract The geometrical errors are affected by many factors for a multi-axis machine tool, such as materials, manufacturing, assembly, measurement, control, and environmental. The geometric error will eventually be reflected in the accuracy of the workpiece; therefore, for each part of the machine tool, the measurement of geometric error is essential. Most geometrical errors are measured separately for each axis. The single geometrical error measurement method is time-consuming. The multiple geometric error measurement methods have some limitations based on different instruments. Laser tracker based on GPS (Global Positioning System) positioning principle can measure the dimensional coordinate. Thus, the laser tracker measured geometric errors in high efficiency, high precision, wide range. This paper introduces the method of measuring the multi-axis machine geometrical error by using a laser tracker with a 1280mm×1280mm×240mm range and compares the measurement result from the traditional method. The results show the laser tracker method has high measurement accuracy, and rapid measurement and compensation of geometrical errors are achievable on a large-stroke machine tools.

Стилі APA, Harvard, Vancouver, ISO та ін.

Cristofolini, Ilaria, Melania Pilla, Andrea Rao, Stefano Libardi, and Alberto Molinari. "Dimensional and geometrical precision of powder metallurgy parts sintered and sinterhardened at high temperature." International Journal of Precision Engineering and Manufacturing 14, no. 10 (October 2013): 1735–42. http://dx.doi.org/10.1007/s12541-013-0233-5.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Relea, Eduard, Lukas Weiss, and Konrad Wegener. "Experimental Study on the Geometrical and Dimensional Stability of Natural Stone Sorts for Precision Machinery." Procedia CIRP 80 (2019): 89–94. http://dx.doi.org/10.1016/j.procir.2019.01.107.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Mühlstädt, Mike, Wolfgang Seifert, Matthias ML Arras, Stefan Maenz, Klaus D. Jandt, and Jörg Bossert. "An advanced geometrical model for laminated woven fabrics using Lamé exponents with enhanced accuracy." Journal of Composite Materials 52, no. 11 (August 23, 2017): 1443–55. http://dx.doi.org/10.1177/0021998317725570.

Повний текст джерела

Анотація:

Three-dimensional stiffness tensors of laminated woven fabrics used in high-performance composites need precise prediction. To enhance the accuracy in three-dimensional stiffness tensor prediction, the fabric’s architecture must be precisely modeled. We tested the hypotheses that: (i) an advanced geometrical model describes the meso-level structure of different fabrics with a precision higher than established models, (ii) the deviation between predicted and experimentally determined mean fiber-volume fraction ( cf) of laminates is below 5%. Laminates of different cf and fabrics were manufactured by resin transfer molding. The laminates’ meso-level structure was determined by analyzing scanning electron microscopy images. The prediction of the laminates’ cf was improved by up to 5.1 vol% ([Formula: see text]%) compared to established models. The effect of the advanced geometrical model on the prediction of the laminate’s in-plane stiffness was shown by applying a simple mechanical model. Applying an advanced geometrical model may lead to more accurate simulations of parts for example in automotive and aircraft.

Стилі APA, Harvard, Vancouver, ISO та ін.

Battey, H. S., and D. R. Cox. "High dimensional nuisance parameters: an example from parametric survival analysis." Information Geometry 3, no. 2 (August 9, 2020): 119–48. http://dx.doi.org/10.1007/s41884-020-00030-6.

Повний текст джерела

Анотація:

AbstractParametric statistical problems involving both large amounts of data and models with many parameters raise issues that are explicitly or implicitly differential geometric. When the number of nuisance parameters is comparable to the sample size, alternative approaches to inference on interest parameters treat the nuisance parameters either as random variables or as arbitrary constants. The two approaches are compared in the context of parametric survival analysis, with emphasis on the effects of misspecification of the random effects distribution. Notably, we derive a detailed expression for the precision of the maximum likelihood estimator of an interest parameter when the assumed random effects model is erroneous, recovering simply derived results based on the Fisher information in the correctly specified situation but otherwise illustrating complex dependence on other aspects. Methods of assessing model adequacy are given. The results are both directly applicable and illustrate general principles of inference when there is a high-dimensional nuisance parameter. Open problems with an information geometrical bearing are outlined.

Стилі APA, Harvard, Vancouver, ISO та ін.

Monroy, Karla, Jordi Delgado, Lidia Sereno, Joaquim Ciurana, and Nicolas J. Hendrichs. "Geometrical feature analysis of Co-Cr-Mo single tracks after selective laser melting processing." Rapid Prototyping Journal 21, no. 3 (April 20, 2015): 287–300. http://dx.doi.org/10.1108/rpj-11-2013-0122.

Повний текст джерела

Анотація:

Purpose – Therefore, the purpose of this study is to understand the relationships between the processing parameters and the geometric form of the produced single tracks, in order to control dimensional quality in future experimentations. The quality of the deposited single track and layer is of prime importance in the selective laser melting (SLM) process, as it affects the product quality in terms of dimensional precision and product performance. Design/methodology/approach – In this paper, a vertical milling machining center equipped with an Ytterbium-fiber laser was used in the SLM experimentation to form single cobalt-chromium-molybdenum (CoCrMo) tracks. The different geometric features and the influence of the scanning parameters on these morphologic characteristics were studied statistically by means of ANOVA. Findings – Evidently, track height (h1) inaccuracy reduced in layer thicknesses between 100 and 200 μm. The re-melt depth (h2) was determined by the energy parameters, with laser power of 325-350 W and scanning speed (SS) of 66.6-83.3 mm/s being the most favorable parameters to obtain the required anchoring. Moreover, a contact angle of 117° was proposed as optimal, as it permitted an adequate overlapping region and a full densification, and, finally, an SS of 50 mm/s and a layer thickness of 250 were suggested for its development. Originality/value – The comprehension of the phenomena inherent to the process is related to the single track geometrical characteristics, which allow the definition of an optimal value for each factor for a further proposal of processing conditions that can finally derive a higher precision, wetting, density and mechanical properties.

Стилі APA, Harvard, Vancouver, ISO та ін.

Ji, H. Z., L. Yuan, and D. B. Shan. "Study on geometrical and dimensional changes in isothermal precision forging with complex shape during air cooling process." Materials Research Innovations 15, sup1 (February 2011): s466—s469. http://dx.doi.org/10.1179/143307511x12858957675831.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Ueng, Shyh-Kuang, Hsin-Cheng Huang, Chieh-Shih Chou, and Hsuan-Kai Huang. "Layered manufacturing for medical imaging data." Advances in Mechanical Engineering 11, no. 8 (August 2019): 168781401987139. http://dx.doi.org/10.1177/1687814019871392.

Повний текст джерела

Анотація:

Layered manufacturing techniques have been successfully employed to construct scanned objects from three-dimensional medical image data sets. The printed physical models are useful tools for anatomical exploration, surgical planning, teaching, and related medical applications. Before fabricating scanned objects, we have to first build watertight geometrical representations of the target objects from medical image data sets. Many algorithms had been developed to fulfill this duty. However, some of these methods require extra efforts to resolve ambiguity problems and to fix broken surfaces. Other methods cannot generate legitimate models for layered manufacturing. To alleviate these problems, this article presents a modeling procedure to efficiently create geometrical representations of objects from computerized tomography scan and magnetic resonance imaging data sets. The proposed procedure extracts the iso-surface of the target object from the input data set at the first step. Then it converts the iso-surface into a three-dimensional image and filters this three-dimensional image using morphological operators to remove dangling parts and noises. At the next step, a distance field is computed in the three-dimensional image space to approximate the surface of the target object. Then the proposed procedure smooths the distance field to soothe sharp corners and edges of the target object. Finally, a boundary representation is built from the distance field to model the target object. Compared with conventional modeling techniques, the proposed method possesses the following advantages: (1) it reduces human efforts involved in the geometrical modeling process. (2) It can construct both solid and hollow models for the target object, and wall thickness of the hollow models is adjustable. (3) The resultant boundary representation guarantees to form a watertight solid geometry, which is printable using three-dimensional printers. (4) The proposed procedure allows users to tune the precision of the geometrical model to compromise with the available computational resources.

Стилі APA, Harvard, Vancouver, ISO та ін.

FANG, CHONGHUA, QIAN LIU, and XIAONAN ZHAO. "IMPROVED INTEGRATED MODEL OF ELECTROMAGNETIC SCATTERING FOR TWO DIMENSIONAL FRACTAL SEA SURFACE." International Journal of Modern Physics B 24, no. 22 (September 10, 2010): 4217–24. http://dx.doi.org/10.1142/s0217979210056542.

Повний текст джерела

Анотація:

In this paper, an improved integrated model of electromagnetic scattering for two dimensional fractal sea surface is built. Both geometrical fractal characteristic and permittivity characteristic of sea water are strictly considered, especially for the effects of salinity and temperature on the electromagnetic field scattered by sea water are added on. Finally, the calculated results from the new model are in accord with experimental results in terms of backscattering coefficient of sea water with no more than 2 dB error, which present higher precision than those traditional models. Thus, by using this model, the whole electromagnetic scattering characteristics of sea surface are obtained.

Стилі APA, Harvard, Vancouver, ISO та ін.

Abeni, Andrea, Alessandro Metelli, Cristian Cappellini, and Aldo Attanasio. "Experimental Optimization of Process Parameters in CuNi18Zn20 Micromachining." Micromachines 12, no. 11 (October 21, 2021): 1293. http://dx.doi.org/10.3390/mi12111293.

Повний текст джерела

Анотація:

Ultraprecision micromachining is a technology suitable to fabricate miniaturized and complicated 3-dimensional microstructures and micromechanisms. High geometrical precision and elevated surface finishing are both key requirements in several manufacturing sectors. Electronics, biomedicals, optics and watchmaking industries are some of the fields where micromachining finds applications. In the last years, the integration between product functions, the miniaturization of the features and the increasing of geometrical complexity are trends which are shared by all the cited industrial sectors. These tendencies implicate higher requirements and stricter geometrical and dimensional tolerances in machining. From this perspective, the optimization of the micromachining process parameters assumes a crucial role in order to increase the efficiency and effectiveness of the process. An interesting example is offered by the high-end horology field. The optimization of micro machining is indispensable to achieve excellent surface finishing combined with high precision. The cost-saving objective can be pursued by limiting manual post-finishing and by complying the very strict quality standards directly in micromachining. A micro-machining optimization technique is presented in this a paper. The procedure was applied to manufacturing of main-plates and bridges of a wristwatch movement. Cutting speed, feed rate and depth of cut were varied in an experimental factorial plan in order to investigate their correlation with some fundamental properties of the machined features. The dimensions, the geometry and the surface finishing of holes, pins and pockets were evaluated as results of the micromachining optimization. The identified correlations allow to manufacture a wristwatch movement in conformity with the required technical characteristics and by considering the cost and time constraints.

Стилі APA, Harvard, Vancouver, ISO та ін.

Більше джерел

Дисертації з теми "Dimensional and geometrical precision"

Toledo, Dos Santos Daniel. "High temperature sintering: investigation of the dimensional precision and mechanical properties of low alloyed steels." Doctoral thesis, Università degli studi di Trento, 2021. http://hdl.handle.net/11572/310431.

Повний текст джерела

Анотація:

The automobile industry has set the demand regarding Powder Metallurgy (PM) parts for decades, since this near-net shape technology is a cost-effective manufacturing process allying good mechanical properties with dimensional and geometrical precision. Aiming at the future of the electric automobiles high production and demand, many changes are on the way to guarantee the competitiveness of PM against other manufacturing process. The high costs of alloying elements such as Ni and Cu, the changes in health and safety regulations as well as light weighting of components are the topics of major importance in the field of PM and focus of main R&D around the globe. The use of high temperature sintering and different alloying elements are possible solutions to overcome properties obtained by using Ni as an alloying element sintered at conventional temperatures. Materials with Cr, Mo and Si were investigated using high temperature sintering (1180°C and 1250°) in comparison to traditionally high Ni materials sintered at conventional temperature (1120°C). The dimensional stability, geometrical precision, density, and microstructure of ring-shaped specimens were studied by using a coordinate measuring machine (CMM) and the effect of HTS on the mechanical properties were estimated through the fraction of the load bearing section. The effect of HTS on the dimensional precision and geometrical stability was later investigated in real parts manufactured by industrial partners through an EPMA Club Project. The 4%Ni material sintered at 1120°C was also compared to Ni-less/Ni-free materials sintered at 1250°C using tensile testing, impact testing, and hardness. The use of HTS to improve the mechanical properties without impairing the dimensional and geometrical stability was confirmed in parts with both low and high complexity designs. This project sets the blueprint for future material developments using HTS as manufacturing process.

Стилі APA, Harvard, Vancouver, ISO та ін.

Pilla, Melania. "Effect of process parameters on the dimensional and geometrical precision of PM steel parts." Doctoral thesis, Università degli studi di Trento, 2013. https://hdl.handle.net/11572/368880.

Повний текст джерела

Анотація:

The standard powder metallurgy process is composed by three main step, the powder production, the compaction and the sintering, and the possible secondary operation that allow to improve the mechanical properties and/or the dimensional and geometrical precision. The present work aims at investigating the influence of processing variables on the dimensional and geometrical precision of parts produced by Powder Metallurgy.

Стилі APA, Harvard, Vancouver, ISO та ін.

Sozak, Ahmet. "Uncertainty Analysis Of Coordinate Measuring Machine (cmm) Measurements." Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/2/12608887/index.pdf.

Повний текст джерела

Анотація:

In this thesis, the measurement uncertainty of Coordinate Measuring Machine (CMM) is analysed and software is designed to simulate this. Analysis begins with the inspection of the measurement process and structure of the CMMs. After that, error sources are defined with respect to their effects on the measurement and then an error model is constructed to compensate these effects. In other words, systematic part of geometric, kinematic and thermal errors are compensated with error modelling. Kinematic and geometric error model is specific for the structure of CMM under inspection. Also, a common orthogonal kinematic model is formed and with using the laser error data of the CMM and error maps of the machine volume is obtained. Afterwards, the models are compared with each other by taking the difference and ratio. The definition and compensation of the systematic errors leave the uncertainty of measurements for analysing. Measurement uncertainty consists of the uncompensated systematic errors and random errors. The other aim of the thesis is to quantify these uncertainties with using the different methods and to inspect the success of these methods. Uncertainty budgeting, comparison, statistical evaluation by designing an experiments and simulation methods are examined and applied to the CMM under inspection. In addition, Virtual CMM software is designed to simulate the task specific measurement uncertainty of circle, sphere and plane without using the repeated measurements. Finally, the performance of the software, highly depending on the mathematical modelling of machine volume, is tested by using actual measurements.

Стилі APA, Harvard, Vancouver, ISO та ін.

Ikegawa, Yojiro. "Three-dimensional geometrical analysis of rock mass structure." Thesis, Imperial College London, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.294135.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Murugan, Jeffrey. "Geometrical and nonperturbative aspects of low dimensional field theories." Master's thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/7681.

Повний текст джерела

Анотація:

Bibliography: leaves 84-88
We present a collection of results on solitons in low-dimensional classical field theory. We begin by reviewing the geometrical setting of he nonlinear ơ-model and demonstrate the integrability of the theory in two-dimensions on a symmetric target manifold. After reviewing the construction of soliton solutions in the 0(3) ơ-model we consider a class of gauged nonlinear ơ-models on two-dimensional axially-symmetric target spaces. We show that, for a certain choice of self-interaction, these models are all self-dual and analyze the resulting Bogomol'nyi equations in the BPS limit using techniques from dynamical systems theory. Our analysis is then extended to topologically massive gauge fields. We conclude with a deviation into exploring links between four-dimensional self-dual Yang-Mills equations and various lower-dimensional field theories. In particular, we show that at the level of equations of motion, the Euclidean Yang-Mills equations in light-cone coordinates reduce to the two-dimensional nonlinear ơ-model.

Стилі APA, Harvard, Vancouver, ISO та ін.

Lindqvist, Richard. "Geometrical and dimensional Measurement Planning : - a systematic and holistic approach." Licentiate thesis, KTH, Mätteknik och optik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-42163.

Повний текст джерела

Анотація:

För att försäkra sig om den slutliga kvaliteten på maskinbearbetade komponenter måste tillverkande företag mäta och verifiera de geometriska och dimensionella egenskaperna på komponenter innan dem skickas vidare nedströms till den mer värdeskapande monteringen. Det är idag vanligt att den geometriska och dimensionella mätningen och verifieringen uppstår varje gång då en maskin ställs om, när man startar om eller startar upp en ny produktionslina eller då en produktionsprocess ändras. Produktionsteknisk mätteknik och resultat från utförda mätningar används sedan som indata för statistisk processtyrning och övervakning av produktionsprocesser. Syftet med vår forskning har varit att först ta fram en nulägesbild av mätteknisk beredning inom fordons- och flygindustrin och utifrån den identifiera framtida trender med behovsanalys och gap. Utifrån analysen har vi sedan utforskat och utvecklat en modell och metodik för mätteknisk mät- och styrbarhetsberedning. I denna licentiat avhandling har vi utforskat området geometrisk och dimensionell mät- och styrbarhetsberedning (GMCP - Geometrical and dimensional Measurement and Controllability Planning). Vi presenterar en nulägesanalys av området och vi presenterar en teori med modell och ramverk för GMCP. Vidare har vi utforskat en metodik och verktyg benämnd kvalitetssäkringsmatris (QAM - Quality Assurance Matrix) och som vi lyfter fram i denna avhandling. I slutet av avhandlingen presenteras och diskuteras dem hittills uppnådda resultaten från forskningen och i det sista kapitlet dras slutsatser och den fortsatta forskningen inom ”SIMET-GICP” projektet presenteras.
In order to ensure final product quality on machined components, manufacturing enterprises must measure and inspect the geometrical and dimensional characteristics of components before they go into higher-value assemblies. Commonly, the geometrical and dimensional measurement and inspection occurs every time at machine tool set-up, when a line is restarted or if the production process is changed. Production metrology and results from production measurements is used as input data for statistical process control and monitoring of production processes. The purpose of our research has been to firstly perform a state of the art analysis in the area of measurement planning applied in the automotive and aerospace industry. The output from the state of the art study has then been used to identify future trends and needs including a gap analysis. Then we used the analysis to explore and develop a model and methodology for measurement and controllability planning. In this licentiate thesis we have explored the area of GMCP (Geometrical and dimensional Measurement and Controllability Planning). As a major result in this thesis a state of the art survey on GMCP is presented. Based on the state of the art study a theory and model framework for GMCP has been explored and a methodology and tool called QAM (Quality Assurance Matrix) is highlighted in this thesis. In the end of the thesis we present and discuss the present research results we have accomplished and in the final chapter we draw conclusions and outline the continued research within the SIMET-GICP project.
QC 20111027
SIMET 1

Стилі APA, Harvard, Vancouver, ISO та ін.

Trevor, Simon. "Dimensional accuracy of investment casting shells /." [St. Lucia, Qld.], 2000. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16943.pdf.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Hübner, Matthias, Monireh Fazeli, Thomas Gereke, and Chokri Cherif. "Geometrical design and forming analysis of three-dimensional woven node structures." Sage, 2018. https://tud.qucosa.de/id/qucosa%3A35533.

Повний текст джерела

Анотація:

Structural frames have been established in many technical applications and typically consist of interconnected profiles. The profiles are commonly joined with node elements. For lightweight structures, the use of composite node elements is expedient. Due to the anisotropic mechanical properties of the fibers, high demands are placed on the orientation of the fibers in the textile reinforcement structure. A continuous fiber course around the circumference and at the junctions is necessary for an excellent force transmission. A special binding and forming process was developed based on the weaving technology. It allows the production of near-net-shaped node elements with branches in any spatial direction, which meet the requirements of load-adjusted fiber orientation. The principles by which these three-dimensional (3D) node elements are converted into a suitable geometry for weaving as a net shape multilayer fabric are reported. The intersections of the branches are described mathematically and flattened to a plane. This is the basis for the weave pattern development. Forming simulations on the macro- and meso-scales complement the analyses. A macro-scale model based on the finite element method (FEM) is used to verify the general formability and the accuracy of the flattenings. Since yarns are pulled through the textile structure in the novel forming process, the required tensile forces and the pulling lengths of the individual yarns are analyzed with a meso-scale FEM model. The flattening for two different node structures is realized successfully, and the simulation proves formability. Furthermore, the necessary forming forces are determined. Finally, the developed method for flattening the 3D geometry is suitable for the design of a variety of spatial node structures and the simulation supports the design of automated forming processes.

Стилі APA, Harvard, Vancouver, ISO та ін.

Humberston, Benjamin. "Precision manipulations using a low-dimensional haptic interface." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/49994.

Повний текст джерела

Анотація:

When interacting with physical objects using their own hands, humans display effortless dexterity. It remains a non-intuitive task, however, to specify the motion of a virtual character’s hand or of a robotic manipulator. Creating these motions generally requires animation expertise or extensive periods of offline motion capture. This thesis presents a real-time, adaptive animation interface, specifically designed around haptic (i.e., touch) feedback, for creating precision manipulations of virtual objects. Using this interface, an animator controls an abstract grasper trajectory while the full hand pose is automatically shaped by compliant scene interactions and proactive adaptation. Haptic feedback enables intuitive control by mapping interaction forces from the full animated hand back to the reduced animator feedback space, invoking the same sensorimotor control systems utilized in natural precision manipulations. We provide an approach for online, adaptive shaping of the animated manipulator using our interface based on prior interactions, resulting in more functional and appealing motions. In a user study with nonexpert participants, we tested the effectiveness of haptic feedback and proactive adaptation of grasp shaping. Comparing the quality of motions produced with and without force rendering, haptic feedback was shown to be critical for efficiently communicating contact forces and dynamic events to the user. The effects of proactive shaping, though inarguably beneficial to visual quality, resulted in mixed behavior for our grasp quality metrics.
Science, Faculty of
Computer Science, Department of
Graduate

Стилі APA, Harvard, Vancouver, ISO та ін.

Rayer, Mathieu. "Chromatic confocal gauging for high precision dimensional metrology." Thesis, Heriot-Watt University, 2015. http://hdl.handle.net/10399/3149.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Більше джерел

Книги з теми "Dimensional and geometrical precision"

3 dimensional design. Lafayette, Calif: C & T Pub., 1988.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

R, DeJarnette Fred, and United States. National Aeronautics and Space Administration. Scientific and Technical Information Division., eds. An interactive user-friendly approach to surface-fitting three-dimensional geometries. [Washington, DC]: National Aeronautics and Space Administration, Scientific and Technical Information Division, 1988.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Cheatwood, F. McNeil. An interactive user-friendly approach to surface-fitting three-dimensional geometries. Hampton, Va: Langley Research Center, 1988.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Saunders, Paul Leslie. Precision measurement trends and requirements for complex three dimensional geometry components. Birmingham: University of Birmingham, 1998.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Computer-aided geometric design: A totally four-dimensional approach. Tokyo: Springer, 2002.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Asgharian-Jeddi, Ali-Asghar. The study of dimensional and geometrical properties of weft knitted fabrics constructed from cotton yarns. Leicester: Leicester Polytechnic, 1985.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Dybała, Bogdan. Integracja i spójność modeli w inżynierii odwrotnej: Wybrane aspekty technicznych i medycznych zastosowań reverse engineering = Integration and traceability of reverse engineering models : selected aspects of technical and medical applications of RE. Wrocław: Oficyna Wydawnicza Politechniki Wrocławskiej, 2013.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Reddy, C. J. Analysis of three-dimensional-cavity-backed aperture antennas using a combined finite element method/method of moments/geometrical theory of diffraction technique. Hampton, Va: Langley Research Center, 1995.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Center, Langley Research, ed. Analysis of three-dimensional-cavity-backed aperture antennas using a combined finite element method/method of moments/geometrical theory of diffraction technique. Hampton, Va: National Aeronautics and Space Administration, Langley Research Center, 1995.

Знайти повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Більше джерел

Частини книг з теми "Dimensional and geometrical precision"

Zago, Marco, Ilaria Cristofolini, and Sasan Amirabdollahian. "Designing Powder Metallurgy Process - The Influence of High Sintering Temperature on Dimensional and Geometrical Precision." In Lecture Notes in Mechanical Engineering, 3–8. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-70566-4_2.

Повний текст джерела

Анотація:

AbstractThe precision of parts produced by Powder Metallurgy (PM) strongly depends on the careful design of PM process parameters. Among them, high sintering temperature is generally considered as detrimental for dimensional and geometrical precision, and therefore neglected in industrial production. Nevertheless, high sintering temperature would strongly improve mechanical characteristics of PM parts, so that the real influence of high sintering temperature on dimensional and geometrical precision is of great interest for PM companies. This study investigates the influence of sintering temperature (up to 1350 °C) on dimensional and geometrical precision of real parts. Dimensional changes on sintering and the effect of sintering temperature have been evaluated. Geometrical characteristics have been measured both in the green and in the sintered state, and the real influence of sintering temperature has been highlighted. As a conclusion, it has been demonstrated that the larger shrinkage due to the high sintering temperature is not detrimental with respect to the dimensional precision, being it reliably predictable. Moreover, the influence on geometrical characteristics is unexpectedly low. The encouraging results of this study convinced the main PM companies in Europe to further investigate the influence of high sintering temperature, as partners in a Club Project within the European Powder Metallurgy Association (EPMA).

Стилі APA, Harvard, Vancouver, ISO та ін.

Elrawashdeh, Zeina, Philippe Revel, Christine Prelle, and Frédéric Lamarque. "High Precision Fabrication of an Innovative Fiber-Optic Displacement Sensor." In Lecture Notes in Mechanical Engineering, 48–55. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-18326-3_5.

Повний текст джерела

Анотація:

AbstractThis study presents the high precision fabrication technique, employed to manufacture a 3D conical grating, used as the reflector element, for a fiber-optic displacement sensor. To get high performance in terms of the surface quality, as well as a dimensional precision, the surface of the reflector must be a polished-mirror surface. To do so, a high precision turning machine along with aluminum alloy were the technical choices made. Two prototypes with different geometric dimensions, have been fabricated using the same machining strategy. Single crystal diamond tool was chosen, to obtain high surface roughness. The followed machining procedure was divided into two main parts; the first part achieves several cuts, to get the desired dimensions, and the last cut is deduced to get the desired nanometric roughness. Good results have been obtained, which validates the followed machining procedure.

Стилі APA, Harvard, Vancouver, ISO та ін.

Beck, M., K. R. Riedmüller, M. Liewald, A. Bertz, M. J. Aslan, and D. Carl. "Investigation on the Influence of Geometric Parameters on the Dimensional Accuracy of High-Precision Embossed Metallic Bipolar Plates." In Lecture Notes in Production Engineering, 427–38. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-18318-8_44.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Arikapudi, R., S. Vougioukas, and T. Saracoglu. "Orchard tree digitization for structural-geometrical modeling." In Precision agriculture '15, 329–36. The Netherlands: Wageningen Academic Publishers, 2015. http://dx.doi.org/10.3920/978-90-8686-814-8_40.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Ferrucci, Massimiliano, Han Haitjema, and Richard Leach. "Dimensional Metrology." In Basics of Precision Engineering, 151–203. Boca Raton : Taylor & Francis, a CRC title, part of the Taylor & Francis imprint, a member of the Taylor & Francis Group, the academic division of T&F Informa, plc, [2018]: CRC Press, 2018. http://dx.doi.org/10.1201/9781351204118-5.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Benelli, Francesco. "The Palazzo del Podestà in Bologna: Precision and Tolerance in a Building all’Antica." In Geometrical Objects, 61–77. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05998-3_3.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Kim, Seung-Woo, Yoon-Soo Jang, Jiyong Park, and Wooram Kim. "Dimensional Metrology Using Mode-Locked Lasers." In Precision Manufacturing, 1–33. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-10-4912-5_1-1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Kim, Seung-Woo, Yoon-Soo Jang, Jiyong Park, and Wooram Kim. "Dimensional Metrology Using Mode-Locked Lasers." In Precision Manufacturing, 1–34. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-10-4938-5_1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Zhang, Hao, Liyuan He, Chunsheng Wang, and Linlin Gao. "Study of Control of Body Geometric Dimensions Precision." In Proceedings of SAE-China Congress 2015: Selected Papers, 163–70. Singapore: Springer Singapore, 2015. http://dx.doi.org/10.1007/978-981-287-978-3_16.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Zanini, Filippo, and Simone Carmignato. "X-Ray Computed Tomography for Dimensional Metrology." In Precision Manufacturing, 1–48. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-10-4912-5_19-1.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Тези доповідей конференцій з теми "Dimensional and geometrical precision"

Yang, Zhaohui, Jun Hong, Jinhua Zhang, Micheal Yu Wang, and Baotong Li. "A New Method to Analyze Three-Dimensional Non-Repetitive Run-Out (3D-NRRO) of Angular Contact Ball Bearings." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-65848.

Повний текст джерела

Анотація:

As ultra-precision index of high-precision ball bearings, the value of three-dimensional non-repetitive run-out (3D-NRRO) directly influences the rotation accuracy in complex mechanical system. Reducing 3D-NRRO contributes to improve the quality of manufacturing in machining tools. This paper develops five-freedom model to analyze the 3D-NRRO of an angular contact ball bearing caused by geometrical errors of the rings raceways and the balls. In the model, the variation of contact angle caused by centrifugal force of balls is taken into consideration, and the geometrical errors of rings raceway and balls are described by Fourier series. Meanwhile, based on Hertzian contact theory and the solution method of dimensional chains, the 3D-NRRO analytical program has been developed, the value of 3D-NRRO analysis is shown. From the results, the relationship between the 3D-NRRO and the geometrical errors of rings raceway and balls are analyzed quantitatively. Findings of this paper provide theoretical supports to reduce or control the 3D-NRRO by optimizing manufacturing process of bearing components.

Стилі APA, Harvard, Vancouver, ISO та ін.

He, Boxia, Yong He, Fu-long Ren, and Rong Xue. "Automatic measurement method of two-dimensional complex geometric features." In International Symposium on Precision Engineering Measurement and Instrumentation 2012, edited by Jie Lin. SPIE, 2013. http://dx.doi.org/10.1117/12.2015272.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Forster, Charles, and Emmanuel Doré. "Automatic Determination of the Small Displacements in a Mechanical Assembly of Two Parts." In ASME 2001 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/detc2001/dac-21053.

Повний текст джерела

Анотація:

Abstract Herein is proposed an automatic method by which the precision of a joint realized by the mechanical assembly of two parts may be totally determined. This precision depends on the dimensional and geometrical defaults existing in the parts, and is materialized by additional small displacements of the parts superposed with the kinematics of the joint. In a first step, the parts are represented by their geometrical entities, and the possible contacts existing between these entities. By ≪ sliding ≫ the parts around their nominal position, i.e. by opening or closing contacts between surfaces, one defines a new configuration of the assembly. In a second step, we give the conditions that this new configuration must fulfill to be physically acceptable. No parasitical motion is accepted, it must be possible to compute the small displacement torsor between the two configurations. And finally, no geometrical interferences are tolerated between the parts. In a third step, we apply this method on a simple but instructive bidimensional example.

Стилі APA, Harvard, Vancouver, ISO та ін.

Abdulaliyev, Z. E., N. A. Egrican, and Vedat Karadag. "Three Dimensional Stress Analysis and Optimisation of Elevators for Drilling by Photoelasticity." In ASME 2002 Engineering Technology Conference on Energy. ASMEDC, 2002. http://dx.doi.org/10.1115/etce2002/struc-29020.

Повний текст джерела

Анотація:

Elevators designed to suspend tubing and drilling pipes in tripping operations are complex structures in petroleum drilling processes. Due to complexity of structure of elevators designed to suspend tubing in tripping operations used in oil well service, many stress geometrical concentration zones occur, and the three dimensional stresses can’t be calculated accurately with sufficient precision and easily by analytical and numerical procedures. To determine and optimise the real stresses occurring at these structures, the photoelasticity method is used reliably. Three dimensional models made from optically sensitive materials and freezing of strains technique are applied to analyse the stresses throughout in the present analysis. The obtained results can be applied to test the currently existing package programmes and to write new computer algorithmes for the related systems.

Стилі APA, Harvard, Vancouver, ISO та ін.

Haynes, Mark, Chih-Hang John Wu, B. Terry Beck, Naga Narendra B. Bodapati, and Robert J. Peterman. "Prestressing Steel Reinforcement Wire Bond Index Number." In 2013 Joint Rail Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/jrc2013-2422.

Повний текст джерела

Анотація:

The purpose of this research project is to develop a mathematical model that predicts the bond strength of a prestressing steel reinforcement wire given the known geometrical features of the wire. The geometrical features of the reinforcement wire were measured by a precision non-contact profilometer. With this mathematical model, prestressing reinforcement wires can now be analyzed for their bond strength without destructive testing. This mathematical model has the potential to serve as a quality control assessment in reinforcement wire production. In addition this mathematical model will provide insight into which reinforcement wires provide the greatest bond strength and which combinations of geometrical features of the reinforcement wire are responsible for providing the bond strength. A precision non-contact profilometer has been developed to measure the important geometrical features of the reinforcement wire. The profilometer is capable of sub-micron resolution measurements to provide an extremely high quality three-dimensional rendering of the reinforcement wire surface profile. From this detailed profile data it is then possible to extract all of the relevant geometrical features of the reinforcement wire. A mathematical model has been created by testing a variety of different reinforcement wires available in the market. By correlating the transfer length of concrete prisms made with the reinforcement wires to various geometrical features, several different levels of mathematical correlation complexity have been investigated. The current empirical correlation models under development are first order and combine three to four unique geometrical features of the reinforcement wire which then act as predictors of the concrete prism transfer length. The resulting mathematical model relating the wire geometrical features to transfer length is referred to as the Bond Index Number (BIN). The BIN is shown to provide a numerical measure of the bond strength of prestressing steel reinforcement wire, without the need for performing destructive tests with the reinforcement wire.

Стилі APA, Harvard, Vancouver, ISO та ін.

Cox, Daniel, Glynn Newby, Hyung Wook Park, and Steven Y. Liang. "Performance Evaluation of a Miniaturized Machining Center for Precision Manufacturing." In ASME 2004 International Mechanical Engineering Congress and Exposition. ASMEDC, 2004. http://dx.doi.org/10.1115/imece2004-60431.

Повний текст джерела

Анотація:

The ability to manufacture at the micrometric and even nanometric precision is in strong demand today in view of the increasing need to reduce the size of parts and products in many industrial and commercial sectors. For many of these applications, the technology of mechanical solid tool machining offers promising applicability as it can create truly three-dimensional and one-of-a-kind parts of extremely high resolutions without placing significant limitation on the part materials. For mechanical solid tool machining, the control of three-dimensional motions between machines, tools, and parts to sub-micron level of precision is a perquisite to the realization of manufacturing at such fine scales. One important factor that contributes to the machining process accuracy is the overall size of the machine tool due to the effects of thermal, static, and dynamic stabilities. This paper will assess the technological benefits of miniaturization of machine tools in the context of machine stiffness and accuracy. This paper also presents the design and configuration of a 4-axis miniaturized vertical machining center of positioning accuracy of 4 to 10 nm and a machine volumetric envelop less than 0.03m3, which is several hundred times smaller than traditional machining centers. A series of tests are discussed for performance evaluation of the miniaturized machining center in terms of the achievable finish and part form accuracy with respect to the process parameters and part geometrical complexity in 1-D, 2-D, and 3-D cases.

Стилі APA, Harvard, Vancouver, ISO та ін.

Franco, P., M. Estrems, and F. Faura. "DNC Method for Flatness Reduction by Machine Tool Error Compensation in Planning Processes." In ASME 8th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2006. http://dx.doi.org/10.1115/esda2006-95528.

Повний текст джерела

Анотація:

Milling is a widely used manufacturing process with the main purpose of generating high precision mechanical components of shapes and sizes given by the numerical control programmed cutting tool trajectory. These mechanical components frequently needs the application of milling operations in order to satisfy the technical specifications that corresponds to their dimensional, geometrical and surface quality requirements. For that reason, the effects of different factors such as cutting tool dynamics, fixturing system design, workpiece material behaviour and applied cutting forces on the desired dimensional precision must be studied, as well as cutting tool and machine tool performance. In this work, the relation between machine tool inaccuracies and geometrical tolerances is analyzed, and a methodology is proposed for improving flatness in planing operations by the correction of imperfections detected in cutting tool displacement according to machine tool axis. These machine tool error correction methodology could be implemented in the current CAD/CAM/CAPP techniques as a means of increasing the milling process performance by identification and correction of CNC milling machine imperfections. The deviations in machine tool displacement during cutting process are identified by metrological analysis, and a modified trajectory for cutting tool is defined by direct numerical control (DNC) from systematic error compensation in machine tool.

Стилі APA, Harvard, Vancouver, ISO та ін.

Aminzadeh, Masoumeh, and Thomas Kurfess. "Vision-Based Inspection System for Dimensional Accuracy in Powder-Bed Additive Manufacturing." In ASME 2016 11th International Manufacturing Science and Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/msec2016-8674.

Повний текст джерела

Анотація:

Laser powder-bed fusion (L-PBF) is an additive manufacturing (AM) process that enables fabrication of functional metal parts with near-net-shape geometries. The drawback to L-PBF is its lack of dimensional precision and accuracy. The efficiency of powder fusion process in powder-bed AM processes is highly affected by process errors, powder irregularities as well as geometric factors. Formation of defects such as lack of fusion and over-fusion due to the aforementioned factors causes dimensional errors that significantly damage the precision. This paper addresses the development of an automated in-situ inspection system for powder-bed additive manufacturing processes based on machine vision. The results of the in-situ automated inspection of dimensional accuracy allows for early identification of faulty parts or alternatively in-situ correction of geometric errors by taking appropriate corrective actions. In this inspection system, 2D optical images captured from each layer of the AM part during the build are analyzed and the geometric errors and defects impairing the dimensional accuracy are detected in each layer. To successfully detect geometric errors, fused geometric objects must be detected in the powder layer. Image processing algorithms are effectively designed to detect the geometric objects from images of low contrast captured during the build inside the chamber. The developed algorithms are implemented to a large number of test images and their performance and precision are evaluated quantitatively. The failure probabilities for the algorithms are also determined statistically.

Стилі APA, Harvard, Vancouver, ISO та ін.

Li, Desheng, and Young Sup Kang. "Simulation and Experimental Validation of Tapered Roller Bearing Vibration Induced by Geometrical Imperfection on Cup Raceway." In ASME 2014 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/detc2014-34178.

Повний текст джерела

Анотація:

A three dimensional non-linear vibration model of tapered roller bearings was developed based on an in-house dynamic bearing model (DBM), which simulates the motion of bearing components and their interactions using Hertzian contact, traction, and hydrodynamic/ elastohydrodynamic lubrication models. The vibration model can simulate bearings with distributed and localized geometrical imperfections on their cup raceways, cone raceways, and roller bodies. This paper focuses on the influence of localized cup raceway imperfections on bearing vibration. Three levels of localized defects were intentionally created on cup raceways and quantified using a surface profile gauge. The quantified defects on actual test bearings were used as inputs to the vibration model. The corresponding test bearings were evaluated with a high-precision bearing vibration test machine. Two different bearing designs were used in the study. The simulation and test data were analyzed and compared, and it was found that the simulation results agreed well with the test data.

Стилі APA, Harvard, Vancouver, ISO та ін.

Theodoracatos, Vassilios E., and Dale E. Calkins. "A 3-D Vision System Model for Automatic Object Surface Sensing." In ASME 1992 Design Technical Conferences. American Society of Mechanical Engineers, 1992. http://dx.doi.org/10.1115/detc1992-0166.

Повний текст джерела

Анотація:

Abstract The development of a “light striping” (structured light) based three-dimensional vision system for automatic surface sensing is presented. The three-dimensional world-point reconstruction process and system modeling methodology involves homogeneous coordinate transformations applied in two independent stages; the video imaging stage using three-dimensional perspective transformations, and the mechanical scanning stage, using three-dimensional affine transformations. Concatenation of the two independent matrix models leads to a robust four-by-four matrix system model. The independent treatment of the two-dimensional imaging process from the three-dimensional modeling process, has reduced the number of unknown internal and external geometrical parameters. The reconstructed sectional contours (light stripes) are automatically and in real-time registered with respect to a common world coordinate system in a format compatible with B-spline surface approximation. The reconstruction process is demonstrated by measuring the surface of a 19.5-ft long by 2 feet beam rowing shell. A detailed statistical accuracy and precision analysis shows an average error, 0.2 percent (0.002), of an object’s largest dimension within the the camera’s field-of-view. System sensitivity analysis reveals a nonlinear increase for angles between the normals of the image and laser planes higher than 45 degrees.

Стилі APA, Harvard, Vancouver, ISO та ін.

Звіти організацій з теми "Dimensional and geometrical precision"

Sohn, Lydia L. Geometrical Effects in Two-Dimensional Arrays of Josephson Junctions. Fort Belvoir, VA: Defense Technical Information Center, May 1992. http://dx.doi.org/10.21236/ada252209.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Carson, J. A., E. Barczak, R. Bossert, E. Fisk, P. Mantsch, R. Riley, E. E. Schmidt, and E. E. Jr Schmidt. A device for precision dimensional measurement of superconducting cable. Office of Scientific and Technical Information (OSTI), May 1986. http://dx.doi.org/10.2172/6900129.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Swyt, Dennis A. New concepts of precision dimensional measurement for modern manufacturing. Gaithersburg, MD: National Institute of Standards and Technology, 1991. http://dx.doi.org/10.6028/nist.ir.4644.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Friedman, Shmuel, Jon Wraith, and Dani Or. Geometrical Considerations and Interfacial Processes Affecting Electromagnetic Measurement of Soil Water Content by TDR and Remote Sensing Methods. United States Department of Agriculture, 2002. http://dx.doi.org/10.32747/2002.7580679.bard.

Повний текст джерела

Анотація:

Time Domain Reflectometry (TDR) and other in-situ and remote sensing dielectric methods for determining the soil water content had become standard in both research and practice in the last two decades. Limitations of existing dielectric methods in some soils, and introduction of new agricultural measurement devices or approaches based on soil dielectric properties mandate improved understanding of the relationship between the measured effective permittivity (dielectric constant) and the soil water content. Mounting evidence indicates that consideration must be given not only to the volume fractions of soil constituents, as most mixing models assume, but also to soil attributes and ambient temperature in order to reduce errors in interpreting measured effective permittivities. The major objective of the present research project was to investigate the effects of the soil geometrical attributes and interfacial processes (bound water) on the effective permittivity of the soil, and to develop a theoretical frame for improved, soil-specific effective permittivity- water content calibration curves, which are based on easily attainable soil properties. After initializing the experimental investigation of the effective permittivity - water content relationship, we realized that the first step for water content determination by the Time Domain Reflectometry (TDR) method, namely, the TDR measurement of the soil effective permittivity still requires standardization and improvement, and we also made more efforts than originally planned towards this objective. The findings of the BARD project, related to these two consequential steps involved in TDR measurement of the soil water content, are expected to improve the accuracy of soil water content determination by existing in-situ and remote sensing dielectric methods and to help evaluate new water content sensors based on soil electrical properties. A more precise water content determination is expected to result in reduced irrigation levels, a matter which is beneficial first to American and Israeli farmers, and also to hydrologists and environmentalists dealing with production and assessment of contamination hazards of this progressively more precious natural resource. The improved understanding of the way the soil geometrical attributes affect its effective permittivity is expected to contribute to our understanding and predicting capability of other, related soil transport properties such as electrical and thermal conductivity, and diffusion coefficients of solutes and gas molecules. In addition, to the originally planned research activities we also investigated other related problems and made many contributions of short and longer terms benefits. These efforts include: Developing a method and a special TDR probe for using TDR systems to determine also the soil's matric potential; Developing a methodology for utilizing the thermodielectric effect, namely, the variation of the soil's effective permittivity with temperature, to evaluate its specific surface area; Developing a simple method for characterizing particle shape by measuring the repose angle of a granular material avalanching in water; Measurements and characterization of the pore scale, saturation degree - dependent anisotropy factor for electrical and hydraulic conductivities; Studying the dielectric properties of cereal grains towards improved determination of their water content. A reliable evaluation of the soil textural attributes (e.g. the specific surface area mentioned above) and its water content is essential for intensive irrigation and fertilization processes and within extensive precision agriculture management. The findings of the present research project are expected to improve the determination of cereal grain water content by on-line dielectric methods. A precise evaluation of grain water content is essential for pricing and evaluation of drying-before-storage requirements, issues involving energy savings and commercial aspects of major economic importance to the American agriculture. The results and methodologies developed within the above mentioned side studies are expected to be beneficial to also other industrial and environmental practices requiring the water content determination and characterization of granular materials.

Стилі APA, Harvard, Vancouver, ISO та ін.

Land, Janet L., and Dennis A. Swyt. The external review of the NIST Precision Engineering Division's NAMT project on nanomanufacturing of atom-based dimensional standard, held at NIST on August 15, 1996. Gaithersburg, MD: National Institute of Standards and Technology, 1997. http://dx.doi.org/10.6028/nist.ir.6023.

Повний текст джерела

Стилі APA, Harvard, Vancouver, ISO та ін.

Anderson, Gerald L., and Kalman Peleg. Precision Cropping by Remotely Sensed Prorotype Plots and Calibration in the Complex Domain. United States Department of Agriculture, December 2002. http://dx.doi.org/10.32747/2002.7585193.bard.

Повний текст джерела

Анотація:

This research report describes a methodology whereby multi-spectral and hyperspectral imagery from remote sensing, is used for deriving predicted field maps of selected plant growth attributes which are required for precision cropping. A major task in precision cropping is to establish areas of the field that differ from the rest of the field and share a common characteristic. Yield distribution f maps can be prepared by yield monitors, which are available for some harvester types. Other field attributes of interest in precision cropping, e.g. soil properties, leaf Nitrate, biomass etc. are obtained by manual sampling of the filed in a grid pattern. Maps of various field attributes are then prepared from these samples by the "Inverse Distance" interpolation method or by Kriging. An improved interpolation method was developed which is based on minimizing the overall curvature of the resulting map. Such maps are the ground truth reference, used for training the algorithm that generates the predicted field maps from remote sensing imagery. Both the reference and the predicted maps are stratified into "Prototype Plots", e.g. 15xl5 blocks of 2m pixels whereby the block size is 30x30m. This averaging reduces the datasets to manageable size and significantly improves the typically poor repeatability of remote sensing imaging systems. In the first two years of the project we used the Normalized Difference Vegetation Index (NDVI), for generating predicted yield maps of sugar beets and com. The NDVI was computed from image cubes of three spectral bands, generated by an optically filtered three camera video imaging system. A two dimensional FFT based regression model Y=f(X), was used wherein Y was the reference map and X=NDVI was the predictor. The FFT regression method applies the "Wavelet Based", "Pixel Block" and "Image Rotation" transforms to the reference and remote images, prior to the Fast - Fourier Transform (FFT) Regression method with the "Phase Lock" option. A complex domain based map Yfft is derived by least squares minimization between the amplitude matrices of X and Y, via the 2D FFT. For one time predictions, the phase matrix of Y is combined with the amplitude matrix ofYfft, whereby an improved predicted map Yplock is formed. Usually, the residuals of Y plock versus Y are about half of the values of Yfft versus Y. For long term predictions, the phase matrix of a "field mask" is combined with the amplitude matrices of the reference image Y and the predicted image Yfft. The field mask is a binary image of a pre-selected region of interest in X and Y. The resultant maps Ypref and Ypred aremodified versions of Y and Yfft respectively. The residuals of Ypred versus Ypref are even lower than the residuals of Yplock versus Y. The maps, Ypref and Ypred represent a close consensus of two independent imaging methods which "view" the same target. In the last two years of the project our remote sensing capability was expanded by addition of a CASI II airborne hyperspectral imaging system and an ASD hyperspectral radiometer. Unfortunately, the cross-noice and poor repeatability problem we had in multi-spectral imaging was exasperated in hyperspectral imaging. We have been able to overcome this problem by over-flying each field twice in rapid succession and developing the Repeatability Index (RI). The RI quantifies the repeatability of each spectral band in the hyperspectral image cube. Thereby, it is possible to select the bands of higher repeatability for inclusion in the prediction model while bands of low repeatability are excluded. Further segregation of high and low repeatability bands takes place in the prediction model algorithm, which is based on a combination of a "Genetic Algorithm" and Partial Least Squares", (PLS-GA). In summary, modus operandi was developed, for deriving important plant growth attribute maps (yield, leaf nitrate, biomass and sugar percent in beets), from remote sensing imagery, with sufficient accuracy for precision cropping applications. This achievement is remarkable, given the inherently high cross-noice between the reference and remote imagery as well as the highly non-repeatable nature of remote sensing systems. The above methodologies may be readily adopted by commercial companies, which specialize in proving remotely sensed data to farmers.

Стилі APA, Harvard, Vancouver, ISO та ін.

Gantzer, Clark J., Shmuel Assouline, and Stephen H. Anderson. Synchrotron CMT-measured soil physical properties influenced by soil compaction. United States Department of Agriculture, February 2006. http://dx.doi.org/10.32747/2006.7587242.bard.

Повний текст джерела

Анотація:

Methods to quantify soil conditions of pore connectivity, tortuosity, and pore size as altered by compaction were done. Air-dry soil cores were scanned at the GeoSoilEnviroCARS sector at the Advanced Photon Source for x-ray computed microtomography of the Argonne facility. Data was collected on the APS bending magnet Sector 13. Soil sample cores 5- by 5-mm were studied. Skeletonization algorithms in the 3DMA-Rock software of Lindquist et al. were used to extract pore structure. We have numerically investigated the spatial distribution for 6 geometrical characteristics of the pore structure of repacked Hamra soil from three-dimensional synchrotron computed microtomography (CMT) computed tomographic images. We analyzed images representing cores volumes 58.3 mm³ having average porosities of 0.44, 0.35, and 0.33. Cores were packed with < 2mm and < 0.5mm sieved soil. The core samples were imaged at 9.61-mm resolution. Spatial distributions for pore path length and coordination number, pore throat size and nodal pore volume obtained. The spatial distributions were computed using a three-dimensional medial axis analysis of the void space in the image. We used a newly developed aggressive throat computation to find throat and pore partitioning for needed for higher porosity media such as soil. Results show that the coordination number distribution measured from the medial axis were reasonably fit by an exponential relation P(C)=10⁻C/C0. Data for the characteristic area, were also reasonably well fit by the relation P(A)=10⁻ᴬ/ᴬ0. Results indicates that compression preferentially affects the largest pores, reducing them in size. When compaction reduced porosity from 44% to 33%, the average pore volume reduced by 30%, and the average pore-throat area reduced by 26%. Compaction increased the shortest paths interface tortuosity by about 2%. Soil structure alterations induced by compaction using quantitative morphology show that the resolution is sufficient to discriminate soil cores. This study shows that analysis of CMT can provide information to assist in assessment of soil management to ameliorate soil compaction.

Стилі APA, Harvard, Vancouver, ISO та ін.

Ми пропонуємо знижки на всі преміум-плани для авторів, чиї праці увійшли до тематичних добірок літератури. Зв'яжіться з нами, щоб отримати унікальний промокод!