Relevant bibliographies by topics / Large distance measurements

Academic literature on the topic 'Large distance measurements'

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Published: 14 March 2023

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Journal articles on the topic "Large distance measurements"

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Uno, T., and S. Adachi. "Range distance requirements for large antenna measurements." IEEE Transactions on Antennas and Propagation 37, no. 6 (June 1989): 707–20. http://dx.doi.org/10.1109/8.29357.

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Toma, Toma, Bunyamin Rizki Abdillah, and Murni Marlina Simarmata. "Pentingnya Pengukuran Pupil Distance (PD) Secara Tepat Untuk Menjaga Akurasi Distance Vitror (DV) Kacamata." Jurnal Mata Optik 2, no. 2 (July 31, 2021): 19–27. http://dx.doi.org/10.54363/jmo.v2i2.35.

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Pupil Distance (PD) is measured in millimetres and even a slight variation can cause a number of vision and eye health problems due to inacurately fitting of Distance Vitror (DV). PD must be paralel to DV, therefore PD measurements must be committed throughtly. It requires comprehensive knowledge and technical skill. With the popularity of buying glasses online, a number of websites have come up with do-it-yourself measurements or apps that will take this measurement for you. The problem is that these are not scientifically accurate measurements and are not being performed by professionals. There is a large margin of error and buyers could end up with glasses that hurt their vision—not correct it.This research is aimed to show ideal procedure that must be committed in producing glasses to avoid inacurate PD measurement. The researcher uses library aprroach to gain related data and informations, then discuss the problem and solution in descriptive approach.
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Pisani, Marco, Milena Astrua, and Massimo Zucco. "Improved Acoustic Thermometry for Long-Distance Temperature Measurements." Sensors 23, no. 3 (February 2, 2023): 1638. http://dx.doi.org/10.3390/s23031638.

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Accurate measurements of long distances (in the order of tens of meters or more) are necessary in manufacturing processes of large structures, as, for example, in the aerospace industry. In the most demanding applications, the goal is to achieve a relative accuracy of 10−7 in the measurement of distances (e.g., 1 µm over 10 m). This goal can be obtained with laser interferometers whose accuracy is based on knowledge of the speed of light, which, in turn, depends on the temperature of air. A thermometer based on the measurement of the speed of sound in air has been realized at INRIM. Its purpose is the measurement of the air temperature along the measurement path of the interferometer with an accuracy of 0.1 °C at distances up to 11 m. The paper describes the principle and the experimental setup of the acoustic thermometer and demonstrates its performance by comparison with calibrated reference platinum resistance thermometers. Furthermore, we demonstrate the potentiality of the method to measure the vertical temperature gradient, which is the main error source in triangulation measurements when using laser trackers.
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Zhang, Chengyang, Xishuang Jing, Siyu Chen, Xuanzhe Ling, Jiarong Zou, and Gang Zhao. "Method of improving large-scale measurement accuracy of laser tracker based on photogrammetry." Measurement and Control 52, no. 9-10 (April 15, 2019): 1220–27. http://dx.doi.org/10.1177/0020294018813644.

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Background: When performing the spatial large-scale measurements, the measurement accuracy of laser tracker would decreased with the increase of the measurement distances due to the refraction difference of most optical digital measurement devices. Therefore, this paper proposed a method based on photogrammetry system to improve the large-scale measurement accuracy of the laser tracker. Purpose: The purpose of this method is to improve the large-scale measurement accuracy of the laser tracker by considering the advantages of photogrammetry system such as high measurement accuracy and good portability. Methods: The measurement data from the photogrammetry system would be used as a reference to do correction on measurement results from laser tracker. The coordinate correction method based on Rodrigues’ rotation formula has been discussed. The measurement accuracy of the long-distance point of laser tracker can be significantly improved through the coordinate correction method. Conclusion: Based on the advantages of using photogrammetry system, the proposed method can achieve higher accuracy when measuring the common points at a closer distance than the laser tracker can do when measuring objects far away from instrument. The feasibility of the proposed method has been demonstrated by experiment.
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Sargeant, B., S. Robson, E. Szigeti, P. Richardson, A. El-Nounu, and M. Rafla. "A METHOD TO ACHIEVE LARGE VOLUME, HIGH ACCURACY PHOTOGRAMMETRIC MEASUREMENTS THROUGH THE USE OF AN ACTIVELY DEFORMABLE SENSOR MOUNTING PLATFORM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B5 (June 15, 2016): 123–29. http://dx.doi.org/10.5194/isprs-archives-xli-b5-123-2016.

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When using any optical measurement system one important factor to consider is the placement of the sensors in relation to the workpiece being measured. When making decisions on sensor placement compromises are necessary in selecting the best placement based on the shape and size of the object of interest and the desired resolution and accuracy. One such compromise is in the distance the sensors are placed from the measurement surface, where a smaller distance gives a higher spatial resolution and local accuracy and a greater distance reduces the number of measurements necessary to cover a large area reducing the build-up of errors between measurements and increasing global accuracy. This paper proposes a photogrammetric approach whereby a number of sensors on a continuously flexible mobile platform are used to obtain local measurements while the position of the sensors is determined by a 6DoF tracking solution and the results combined to give a single set of measurement data within a continuous global coordinate system. The ability of this approach to achieve both high accuracy measurement and give results over a large volume is then tested and areas of weakness to be improved upon are identified.
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Sargeant, B., S. Robson, E. Szigeti, P. Richardson, A. El-Nounu, and M. Rafla. "A METHOD TO ACHIEVE LARGE VOLUME, HIGH ACCURACY PHOTOGRAMMETRIC MEASUREMENTS THROUGH THE USE OF AN ACTIVELY DEFORMABLE SENSOR MOUNTING PLATFORM." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B5 (June 15, 2016): 123–29. http://dx.doi.org/10.5194/isprsarchives-xli-b5-123-2016.

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When using any optical measurement system one important factor to consider is the placement of the sensors in relation to the workpiece being measured. When making decisions on sensor placement compromises are necessary in selecting the best placement based on the shape and size of the object of interest and the desired resolution and accuracy. One such compromise is in the distance the sensors are placed from the measurement surface, where a smaller distance gives a higher spatial resolution and local accuracy and a greater distance reduces the number of measurements necessary to cover a large area reducing the build-up of errors between measurements and increasing global accuracy. This paper proposes a photogrammetric approach whereby a number of sensors on a continuously flexible mobile platform are used to obtain local measurements while the position of the sensors is determined by a 6DoF tracking solution and the results combined to give a single set of measurement data within a continuous global coordinate system. The ability of this approach to achieve both high accuracy measurement and give results over a large volume is then tested and areas of weakness to be improved upon are identified.
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Yan, Qing-Zeng, Ji Yang, Yang Su, Yan Sun, Ye Xu, Hongchi Wang, Xin Zhou, and Chen Wang. "Improved Measurements of Molecular Cloud Distances Based on Global Search." Astrophysical Journal 922, no. 1 (November 1, 2021): 8. http://dx.doi.org/10.3847/1538-4357/ac214f.

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Abstract The principle of the background-eliminated extinction-parallax (BEEP) method is examining the extinction difference between on- and off-cloud regions to reveal the extinction jump caused by molecular clouds, thereby revealing the distance in complex dust environments. The BEEP method requires high-quality images of molecular clouds and high-precision stellar parallaxes and extinction data, which can be provided by the Milky Way Imaging Scroll Painting (MWISP) CO survey and the Gaia DR2 catalog, as well as supplementary A V extinction data. In this work, the BEEP method is further improved (BEEP-II) to measure molecular cloud distances in a global search manner. Applying the BEEP-II method to three regions mapped by the MWISP CO survey, we collectively measured 238 distances for 234 molecular clouds. Compared with previous BEEP results, the BEEP-II method measures distances efficiently, particularly for those molecular clouds with large angular size or in complicated environments, making it suitable for distance measurements of molecular clouds in large samples.
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Pillarz, Marc, Axel von Freyberg, and Andreas Fischer. "Determination of the mean base circle radius of gears by optical multi-distance measurements." Journal of Sensors and Sensor Systems 9, no. 2 (August 20, 2020): 273–82. http://dx.doi.org/10.5194/jsss-9-273-2020.

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Abstract. The required reliability of wind turbine gearboxes increases the requirements for large gear measurements. Extensive measurements to reliably assess the geometry of large gears in the single micrometer range are necessary. Due to an individually fixed measuring volume, standard methods like coordinate and gear measuring instruments reach their limits for large gears with diameters > 1 m. Therefore, a scalable optical measurement approach consisting of a single sensor in combination with a rotary table for multi-distance measurements with subsequent model-based evaluation of shape parameters of gears is presented. The scalable measurement approach is to be extended to a multisensory system in further work. As a fundamental shape parameter the mean base circle radius using the example of spur gears is determined. The base circle radius is used due to the geometric relationship to further shape parameters for example to the profile slope deviation. The theoretically achievable measurement uncertainty of the mean base circle radius due to sensor noise is estimated to less than 5 µm (k=2) for a small and a large gear, which verifies the scalability of the sensor system. In order to show a general proof of principle, two series of optical measurements on a gear with a diameter of 0.105 m are performed and referenced with a tactile measurement. As a result, random errors of 1.2 µm for k=2 are determined. The remaining systematic deviations to the reference value amount to 4.3 and 1.6 µm, respectively. Hence, the total measurement uncertainty is currently limited by systematic effects, and the defined aim of a total uncertainty of less than 5 µm (k=2) is narrowly missed by 1.5 µm. The random errors of 1.2 µm (k=2) show, however, that an adequate measurement precision is achieved and that the multi-distance measurement approach has the potential to reach the aimed measurement uncertainty with appropriate strategies to compensate for the systematic influences. The experimental and theoretical results prove the principle applicability of the proposed single sensor multi-distance approach for the precise inspection of gears.
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MAHAL, VERED, and ADY ARIE. "DISTANCE MEASUREMENTS USING FREQUENCY STABILIZED Nd:YAG LASERS." Journal of Nonlinear Optical Physics & Materials 05, no. 03 (July 1996): 543–50. http://dx.doi.org/10.1142/s0218863596000362.

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Two diode-pumped tunable Nd:YAG lasers locked to sub-Doppler transitions of 127I2 and 133 Cs 2 are used as a source for two-wavelength interferometry. The synthetic wavelength, Λ=c/∆ν, is highly stable and accurate, owing to the frequency stability of the locked lasers and the precise determination of the frequency difference Δν between Cs 2 and I 2 transitions. The dense spectra of these molecules allows selection of Λ over a wide range, between 8.5 mm and several meters, thus enabling distance measurements with a large non-ambiguity range. Fringe contrast and phase-shifting methods are used to measure the phase difference. An accuracy of 70 μm is achieved for Λ~19 mm, i.e. Λ/260.
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Garcia Espinilla, Oscar, Irene Sanchez, and Raul Martin. "Intrasession repeatability and agreement of a new method to measure the foveal fixation axis." PeerJ 11 (February 24, 2023): e14942. http://dx.doi.org/10.7717/peerj.14942.

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Purpose Ophthalmic lens adaptation, particularly with progressive addition lenses, requires accurate measurements of the patient nasopupillary distance (NPD) and interpupillary distance (IPD), which are usually collected using the pupil centre as a reference. However, differences between the pupil centre and visual or foveal axis could induce some subsidiary effects of correcting lenses. This study aimed to assess the intrasession repeatability of a new prototype (Ergofocus®; Lentitech, Barakaldo, Spain) that can measure the foveal fixation axis (FFA) distance and assess the agreement with the NPD measurements collected using a traditional method (frame ruler). Methods The FFA at far and near distances was measured three consecutive times in 39 healthy volunteers to determine the intrasession repeatability according to the British Standards Institute and International Organization for Standardization. Additionally, the FFA and NPD (standard frame ruler) were measured in 71 healthy volunteers and compared using Bland–Altman analysis. Two blinded experienced practitioners conducted each FFA and NPD measurement. Results The FFA measurements showed acceptable repeatability at far distances (right eye (RE): Sw = 1.16 ± 0.76 mm and coefficient of variation (CV) = 3.92 ± 2.51%; left eye (LE) Sw = 1.11 ± 0.79 mm and CV = 3.76 ± 2.51%) and at near distances (RE: Sw = 0.97 ± 0.85 mm and CV = 3.52 ± 3.02%; LE: Sw = 1.17 ± 0.96 mm and CV = 4.54 ± 3.72%). Additionally, agreement with the NPD showed large differences at far distances (RE: −2.15 ± 2.34, LoA = −6.73 to 2.43 mm (P < 0.001); LE: −0.61 ± 2.62, LoA = −5.75 to 4.53 mm (P = 0.052)) and near distances (RE: −3.08 ± 2.80, LoA −8.57 to 2.42 mm (P < 0.001); LE: −2.97 ± 3.97, LoA: −10.75 to 4.80 mm (P < 0.001)). Conclusions FFA measurements showed clinically acceptable repeatability at both far and near distances. Agreement with the NPD measured using a standard frame ruler showed significant differences, suggesting that both measurements are not interchangeable in clinical practice to prescribe and center ophthalmic lenses. Further research is necessary to assess the impact of FFA measurement in ophthalmic lens prescriptions.
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Dissertations / Theses on the topic "Large distance measurements"

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Xu, Xiaoying. "Robust Measurement of the Cosmic Distance Scale Using Baryon Acoustic Oscillations." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/241935.

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We present techniques for obtaining precision distance measurements using the baryon acoustic oscillations (BAO) through controlling systematics and reducing statistical uncertainties. Using the resulting distance-redshift relation, we can infer cosmological parameters such as w, the equation of state of dark energy. We introduce a new statistic, ɷ(l)(r(s)), for BAO analysis that affords better control over systematics. It is computed by band-filtering the power spectrum P(k) or the correlation function ξ(r) to extract the BAO signal. This is conducive to several favourable outcomes. We compute ɷ(l)(r(s)) from 44 simulations and compare the results to P(k) and ξ(r). We find that the acoustic scales and theoretical errors we measure are consistent between all three statistics. We demonstrate the first application of reconstruction to a galaxy redshift survey. Reconstruction is designed to partially undo the effects of non-linear structure growth on the BAO, allowing more precise measurements of the acoustic scale. We also present a new method for deriving a smooth covariance matrix based on a Gaussian model. In addition, we develop and perform detailed robustness tests on the ξ(r) model we employ to extract the BAO scale from the data. Using these methods, we obtain spherically-averaged distances to z = 0.35 and z = 0.57 from SDSS DR7 and DR9 with 1.9% and 1.7% precision respectively. Combined with WMAP7 CMB observations, SNLS3 data and BAO measurements from 6dF, we measure w = -1.08 ± 0.08 assuming a wCDM cosmology. This represents a ~8% measurement of w and is consistent with a cosmological constant.The preceding does not capture the expansion history of the universe, H(z), encoded in the line-of-sight distance scale. To disentangle H(z), we exploit the anisotropic BAO signal that arises if we assume the wrong cosmology when calculating the clustering distribution. Since we expect the BAO signal to be isotropic, we can use the magnitude of the anisotropy to separately measure H(z) and D(A)(z). We apply our simple models to SDSS DR7 data and obtain a ~3.6% measurement of D(A)(z=0.35) and a ~8.4% measurement of H(z = 0.35).
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Leonard, Derek Anthony. "Algorithms for Large-Scale Internet Measurements." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8651.

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As the Internet has grown in size and importance to society, it has become increasingly difficult to generate global metrics of interest that can be used to verify proposed algorithms or monitor performance. This dissertation tackles the problem by proposing several novel algorithms designed to perform Internet-wide measurements using existing or inexpensive resources. We initially address distance estimation in the Internet, which is used by many distributed applications. We propose a new end-to-end measurement framework called Turbo King (T-King) that uses the existing DNS infrastructure and, when compared to its predecessor King, obtains delay samples without bias in the presence of distant authoritative servers and forwarders, consumes half the bandwidth, and reduces the impact on caches at remote servers by several orders of magnitude. Motivated by recent interest in the literature and our need to find remote DNS nameservers, we next address Internet-wide service discovery by developing IRLscanner, whose main design objectives have been to maximize politeness at remote networks, allow scanning rates that achieve coverage of the Internet in minutes/hours (rather than weeks/months), and significantly reduce administrator complaints. Using IRLscanner and 24-hour scan durations, we perform 20 Internet-wide experiments using 6 different protocols (i.e., DNS, HTTP, SMTP, EPMAP, ICMP and UDP ECHO). We analyze the feedback generated and suggest novel approaches for reducing the amount of blowback during similar studies, which should enable researchers to collect valuable experimental data in the future with significantly fewer hurdles. We finally turn our attention to Intrusion Detection Systems (IDS), which are often tasked with detecting scans and preventing them; however, it is currently unknown how likely an IDS is to detect a given Internet-wide scan pattern and whether there exist sufficiently fast stealth techniques that can remain virtually undetectable at large-scale. To address these questions, we propose a novel model for the windowexpiration rules of popular IDS tools (i.e., Snort and Bro), derive the probability that existing scan patterns (i.e., uniform and sequential) are detected by each of these tools, and prove the existence of stealth-optimal patterns.
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Lange, Robert [Verfasser]. "3D time of flight distance measurement with custom solid state image sensors in CMOS, CCD technology / presented by Robert Lange." 2000. http://d-nb.info/960293825/34.

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Books on the topic "Large distance measurements"

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Longitude: The story of a lone genius who solved the greatest scientific problem of his time. London: Harper Perennial, 2007.

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Sobel, Dava. Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. New York: MJF Books, 2005.

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Andrewes, William J. H., 1950- and Sobel Dava, eds. The illustrated longitude. London: Fourth Estate, 1998.

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Dava, Sobel, and Andrewes, William J. H., 1950-, eds. The illustrated longitude. New York: Walker, 1998.

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Sobel, Dava. Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. London: Fourth Estate, 1996.

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Jiangbo, Tang, ed. Jing du: Xun zhao di qiu ke du de ren = Longitude. Haikou Shi: Hainan chu ban she, 2000.

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Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. London: Fourth Estate, 1996.

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Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. London: Harper Perennial, 1998.

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Longitude: The true story of a lone genius who solved the greatest scientific problem of his time. New York: Walker, 1995.

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Mills, M. G. L., and M. E. J. Mills. Energetics. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198712145.003.0008.

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Measurements of daily energy expenditure and water turnover showed that energy expenditure in cheetahs was not significantly greater than expected, but water turnover was low. There were no sex differences in daily energy expenditure, but when hunting along riverbeds cheetahs used more energy than when hunting in the dunes, probably because they moved further in the riverbeds. There were no differences in daily energy expenditure between females in different stages of reproduction. Energy expended chasing prey differed; small prey being least costly and large species most costly. Analyses of prey chases using both GPS and accelerometer loggers revealed that there were two phases; an initial rapid acceleration to catch up with the prey, followed by a slowing phase as cheetahs followed twists and turns of the prey as the distance between them closed. A visualization of five phases recorded from accelerometer data during a successful steenbok hunt is presented.
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Book chapters on the topic "Large distance measurements"

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Wang, Yong Qiang, Nai Guang Lu, Wen Yi Deng, and Ming Li Dong. "A New Algorithm with Distance Constraint for Large-Scale Profile Measurement." In Experimental Mechanics in Nano and Biotechnology, 159–62. Stafa: Trans Tech Publications Ltd., 2006. http://dx.doi.org/10.4028/0-87849-415-4.159.

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Lu, Zhanjin, and Zunyu Xu. "Research and practice on gas control technology of long-distance adjacent strata in large inclined coal mining face." In Advances in Measurement Technology, Disaster Prevention and Mitigation, 529–34. London: CRC Press, 2022. http://dx.doi.org/10.1201/9781003330172-72.

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Henderson, Peter A. "Wildlife Population Estimates by Census and Distance Measuring Techniques." In Southwood's Ecological Methods, 281–92. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198862277.003.0009.

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Methodologies based on counting the number of sightings to estimate are described. These techniques are particularly useful for large or easily seen animals such as birds, large grassland mammals, whales, crocodilians, and large, active insects such as butterflies. Point and line survey methods are described. Distance sampling methods, including Fourier series estimators, are presented, and R code listings to undertake the computations presented. Plotless density estimators are described based on nearest-neighbour, and closest-individual measurements are described.
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Breckinridge, James B., Alec M. Pridgeon, and Donald E. Osborn. "In Space at Last." In With Stars in Their Eyes, 407–46. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780190915674.003.0012.

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This chapter discusses how Aden and Marjorie Meinel were hired at NASA/JPL and their contributions in six major areas: (1) the large deployable reflector system study to create technology fundamental to the James Webb Space Telescope; (2) the Thousand Astronomical Unit (TAU) mission to make high-precision, fundamental measurements of the distance from Earth to most objects in this galaxy; (3) space optical systems for the detection and characterization of exoplanets; (4) interferometry to recover images across the surface of stars, measure precision stellar motions, and reveal details of planetary formation and evolution; (5) repair of the Hubble Space Telescope; and (6) the ground-based Advanced Electro Optical System (AEOS) telescope of the Air Force. The chapter ends with the awards Aden and Marjorie both received and their deaths in 2011 and 2008, respectively.
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Liabotis, Ioannis, Babis Theodoulidis, and Mohamad Saraaee. "Improving Similarity Search in Time Series Using Wavelets." In Data Warehousing and Mining, 1116–37. IGI Global, 2008. http://dx.doi.org/10.4018/978-1-59904-951-9.ch064.

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Sequences constitute a large portion of data stored in databases. Data mining applications require the ability to process similarity queries over a large amount of time series data. The query processing performance is an important factor that needs to be taken into consideration. This article proposes a similarity retrieval algorithm for time series. The proposed approach utilizes wavelet transformation in order to reduce the dimensionality of the time series. The transformed series are indexed using X-Trees, which is a spatial indexing technique able to efficiently index high-dimensional data. The article proves that this technique outperforms the usage of the Fourier transformation, since the wavelet transformation provides better approximation of the time series. Through the experiments, it can be concluded that the optimum performance is obtained using 16 to 20 wavelet coefficients. Furthermore, a novel mechanism for reducing the complexity of the calculation for the false alarms removal is proposed. Storing the approximation coefficients of the penultimate level of the decomposition tree, the Euclidean distance between the two sequences is calculated, thus reducing further the number of false alarms before calculating the actual Euclidean distance using the complete time series. The article concludes with a detailed performance evaluation of the proposed similarity retrieval algorithm using data from the Greek stock market and the temperature measurements from Athens. The comparison is done with techniques that use the Haar transform and the R*-Tree, and the proposed algorithm is shown to outperform them.
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Manton, Nicholas, and Nicholas Mee. "Cosmology." In The Physical World. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198795933.003.0015.

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This chapter is about the large-scale structure of the universe, how it is described in general relativity and recent advances in determining the cosmological parameters. The Hubble distance–redshift relationship is discussed. The assumptions of the FRW cosmologies are presented and the FRW solutions of Einstein equation are derived. The FRW model is interpreted in terms of Newtonian gravity. Cosmological redshift is explained. The evidence for dark matter and its possible origin are discussed. The evidence for the Big Bang is presented, including the cosmic microwave background and the latest measurements of the CMB by the Planck probe. The evidence for dark energy is discussed, along with its interpretation as an FRW cosmology with a non-zero cosmological constant. Computer models of galaxy formation are discussed. Outstanding cosmological puzzles are presented along with their possible solution by inflationary models.
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Oriakhi, Christopher O. "Systems of Measurement." In Chemistry in Quantitative Language. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780195367997.003.0006.

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Chemistry is an experimental science that involves measurement of the magnitude of various properties of substances. Measurements generate numbers, and we need units attached to these numbers so we can tell what exactly is being measured. Some examples of quantities measured include amount, mass, pressure, size, temperature, time, volume, etc. There are several systems of units, for example, the English system and the metric system. The metric system is the most commonly used system of measurement in chemistry. In 1960, a modernized version of the metric system known as the Systeme Internationale (or SI system) was recommended for worldwide adoption. The SI, based on the metric system, consists of seven fundamental units and several units derived from them. These units serve all scientific measurements. The seven fundamental units are listed in table 2-1. The fundamental units do have some shortcomings. For example, in some cases the base unit is inconveniently large or small. To overcome this, the SI units can be modified through the use of prefixes. The prefixes define multiples or fractions of the base or fundamental units. Some examples are listed in table 2-2. Mass, length, and time are important quantities commonly measured in science, which are assigned fundamental units. The standard unit of mass in the SI is the kilogram (kg), which is defined as the mass of a certain block of platinum–iridium alloy, also known as the prototype kilogram, kept in a vault at the International Bureau of Weights and Measures, in Sevres, France. Other mass units that are related to the kilogram include gram (g), milligram (mg), and microgram (μg). Here is how they are related: 1000 g = 1 kg 1000 mg = 1 g 1,000,000 μg = 1 g Note that the symbol for grams is g, not gm, gms, gr, or anything else. The SI unit of length is the meter (m), which is defined as the distance light travels in approximately 1/299,792,458 second.
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"Measurements and Analysis Methods of Distant Peculiar Velocities." In Large-Scale Peculiar Motions, 183–203. WORLD SCIENTIFIC, 2021. http://dx.doi.org/10.1142/9789811211812_0013.

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Henderson, Peter A. "Studies at Large Spatial Scales, Citizen Science, and the Classification of Habitats." In Southwood's Ecological Methods, 487–98. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198862277.003.0016.

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Technological advances over the past forty years have greatly increased the opportunities for the study of population and community processes over large spatial distances and to follow changes in large populations. A number of important developments, such as remote sensing, has made this possible. Remote sensing is the measurement of reflected, emitted, or backscattered electromagnetic radiation from the Earth’s surface by using instruments placed at a distance, most often on a satellite, although aircraft are frequently used. Methods to study populations over large spatial scales are introduced. The use of satellites and remote sensing using piloted aircraft and drones and distributed networks of sensors such as camera traps is described. The creation of biodiversity record systems and the development of citizen science with the internet are described. The perception of the change in species richness with spatial scale is discussed. The concept of ecosystem services is introduced. A general system for habitat classification is presented.
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Zhao, Zhengcai, Yao Li, Yucan Fu, and Dawei Ding. "Collision-Free Path Planning for Efficient Inspection of Free-Form Surface by Using a Trigger Probe." In Advances in Transdisciplinary Engineering. IOS Press, 2021. http://dx.doi.org/10.3233/atde210037.

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Measurement path planning plays an essential role in on-machine measurement, which is often required to be time-saving and collision-free. This paper proposes a novel path planning methodology and develops an automatic collision avoidance strategy for measurement. Measurement points are generated by Contour section sampling (CSS), Grid mesh sampling (GMS), and Locally dense sampling (LDS) on the free-form surface. Afterwards, a shortest path algorithm (SPA) and a non-interference path algorithm (NIPA) are developed respectively. The simulations show that the proposed method can reduce the total inspection distance to nearly 7.82% than the original one. The presented path planning method can measure the surface of large aerospace parts directly by using a trigger probe.
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Conference papers on the topic "Large distance measurements"

1

Ben-Chorin, Moshe, Silvia Chuartzman, and Yehiam Prior. "Absolute distance measurements using a noisy interferometer." In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1998. http://dx.doi.org/10.1364/cleo_europe.1998.cfd4.

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The spectrum of white light passing through a Michelson interferometer develops a sinusoidal modulation, the frequency of which is determined by the path difference between the interferometer arms. Dispersive white light interferometry is capable of measuring relatively large distances (hundreds of µm) with high precision, and without moving parts. However, as with all interferometric methods, it is very sensitive to phase noise arising from such factors as vibrations or air turbulence. The random phase jumps reduce the visibility of the white light fringes. This limitation imposes stringent conditions upon the stability of the interferometer, and its applicability to field measurements is thus restricted.
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2

Walsh, C. J., N. Brown, and P. S. Fairman. "Long distance multiwavelength interferometry." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1989. http://dx.doi.org/10.1364/oam.1989.ft6.

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The use of multiple wavelengths in an interferometer to measure absolute distance is well established.1 We previously reported2 on such measurements over distances up to 25 m using a CO2 laser source. At longer distances, the systematic variations in the laser frequency, which produce fluctuations in the interferometer phase, become large enough to cause ambiguities in the algorithms used to calculate the distance in terms of synthetic wavelengths.1
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3

Li, He, Robert G. Landers, and Douglas A. Bristow. "Modeling of Absolute Distance Meter Shift Inside a Laser Tracker." In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/msec2017-3028.

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In the measurement of machine tool and robot geometric errors, one of the most extensively used instruments is the Laser Tracker (LT). Errors in the LT measurements will decrease the effectiveness of the error modeling and compensation methods that utilize these measurements. When the LT’s Absolute Distance Meter (ADM) is used without frequent referencing to a home position, large and long-term shifts occur. The ADM shift directly introduces errors in the radial component of every measurement in spherical coordinates, which will result in measurement errors in the Cartesian coordinates. Although the ADM shift is addressed in newer LT designs using internal referencing hardware, this paper presents a pragmatic and efficient software solution to ADM shift for LTs in which the internal referencing hardware is not embedded. The LT was measured for 22 hr in a temperature-constant room to examine the ADM shift effects on measurements. An ADM shift model was then proposed by assuming that the ADM shift equally affects radial components of all measurements wherever the target is, as long as it is within the measurement range. Another experiment was then performed to test the validity of the proposed model. After the model was identified and errors were corrected, the maximum temporal variation in the radial distance measurement is reduced by 80–86%.
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4

Sun, Shu, George R. MacCartney, and Theodore S. Rappaport. "Millimeter-wave distance-dependent large-scale propagation measurements and path loss models for outdoor and indoor 5G systems." In 2016 10th European Conference on Antennas and Propagation (EuCAP). IEEE, 2016. http://dx.doi.org/10.1109/eucap.2016.7481506.

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5

Hall, J. W., N. Gao, and D. Ewing. "The Three-Dimensional Evolution of the Large-Scale Structures in the Impinging Round Jet." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31419.

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The evolution of the large-scale structures in the impinging round jet were studied by measuring the fluctuating pressure on the impingement surface for nozzle-to-plate distances of 2.0, 3.0 and 4.0 nozzle diameters. It is found that the large-scale vortex ring structures played a much more dominant role when the nozzle-to-plate spacing was 2.0 diameters than for either 3.0 or 4.0 diameters. The results for a nozzle-to-plate spacing of 3.0 nozzle diameters more closely resembles the spacing of 4.0 diameters. The convection velocity of the different azimuthal modes were deduced from radial cross-spectra measurements. It was found that the convection velocity of all the azimuthal modes were similar and the convection speed for the structures measured with the fluctuating pressure were independent of nozzle-to-plate distance.
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6

Linzer, Finn, and Hans-Berndt Neuner. "Transferability of an estimation procedure for distance deviations of terrestrial laser scanners from laboratory to on-site conditions." In 5th Joint International Symposium on Deformation Monitoring. Valencia: Editorial de la Universitat Politècnica de València, 2022. http://dx.doi.org/10.4995/jisdm2022.2022.13853.

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Employing terrestrial laser scanners (TLS) for geodetic deformation measurements requires attaining the highest possible accuracy. In this paper, we estimate the influence of varying incidence angles (IA) and materials on measurements regarding the distance component. Considering not only stochastic characteristics, the use of a scanning total station enables additionally the study of systematic distance deviations. By using the total station ocular, the device is brought into the local coordinate system of a laser tracker via position resection and intersection. The point cloud recording, with a Close-Range scanner, represents the reference. Due to transformation into a common coordinate system, defined by a laser tracker, a distance driven point comparison is possible. To test a large number of conditions an automated setup was developed. For each device, a suitable interface was implemented in the Robot Operating System. After the specimen has been set up, an automatic measurement can be performed for data acquisition. We can demonstrate that different building materials and varying IAs cause systematic distance deviations up to 3 mm magnitude. For measurement objects, this kind of correction must be considered, especially when the measurement configuration varies between measurement epochs. It can be demonstrated that the values and characteristics observed in the laboratory agree to those obtained on-site. However, the chosen approach thereby reveals previously unrecognized challenges that need to be considered for the use of TLS in high-accuracy deformation analysis.
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7

Cappietti, Lorenzo, Irene Simonetti, Andrea Esposito, Maximilian Streicher, Andreas Kortenhaus, Babette Scheres, Holger Schuettrumpf, Matthias Hirt, Bas Hofland, and Xuexue Chen. "Large-Scale Experiments of Wave-Overtopping Loads on Walls: Layer Thicknesses and Velocities." In ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78104.

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Wave-Overtopping loads on vertical walls, such as those located on top of a dike, have been investigated in several small-scale experiments in the past. A large-scale validation for a mild foreshore situation is still missing. Hence the WALOWA (WAve LOads on WAlls) experimental campaign was carried out to address this topic. This paper, first presents a description of the large-scale model, the measurement set-up and the experimental methodologies, then it focuses on the layer thicknesses and velocities of the flows created on the promenade by the wave overtopping. A set of resistive wave gauges, ultrasonic distance sensors and velocimeters have been used to conduct these measurements. Preliminary data analysis and results, related to a 1000 irregular waves long test, are discussed. The momentum flux of these flows is studied and its implications, for the wave-overtopping loads acting on the vertical walls, are highlighted.
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8

Erwin, James P., Neeraj Sinha, and Gregory P. Rodebaugh. "Large Eddy Simulations of Supersonic Impinging Jets." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-70140.

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Supersonic impinging jet flowfields contain self-sustaining acoustic feedback features that create high levels of discrete frequency tonal noise. These types of flowfields are typically found with short takeoff and landing military aircraft as well as jet blast deflector operations on aircraft carrier decks. The US Navy has a goal to reduce the noise generated by these impinging jet configurations and is investing in computational aeroacoustics to aid in the development of noise reduction concepts. In this paper, implicit Large Eddy Simulation (LES) of impinging jet flow-fields are coupled with a far-field acoustic transformation using the Ffowcs Williams and Hawkings (FW-H) equation method. The LES solves the noise generating regions of the flow in the nearfield, and the FW-H transformation is used to predict the far-field noise. The noise prediction methodology is applied to a Mach 1.5 vertically impinging jet at a stand-off distance of five nozzle throat diameters. Both the LES and FW-H acoustic predictions compare favorably with experimental measurements. Time averaged and instantaneous flowfields are shown. A calculation performed previously at a stand-off distance of four nozzle throat diameters is revisited with adjustments to the methodology including a new grid, time integrator, and longer simulation runtime. The calculation exhibited various feedback loops which were not present before and can be attributed to an explicit time marching scheme. In addition, an instability analysis of two heated jets is performed. Tonal frequencies and instability modes are identified for the sample problems.
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9

Okamoto, Akira, and Dean B. Edwards. "Regulating a Formation of a Large Number of Vehicles." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81224.

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Various control algorithms have been developed for fleets of autonomous vehicles. Many of the successful control algorithms in practice are behavior-based control or nonlinear control algorithms, which makes analyzing their stability difficult. At the same time, many system theoretic approaches for controlling a fleet of vehicles have also been developed. These approaches usually use very simple vehicle models such as particles or point-mass systems and have only one coordinate system which allows stability to be proven. Since most of the practical vehicle models are six-degree-of-freedom systems defined relative to a body-fixed coordinate system, it is difficult to apply these algorithms in practice. In this paper, we consider a formation regulation problem as opposed to a formation control problem. In a formation control problem, convergence of a formation from random positions and orientations is considered, and it may need a scheme to integrate multiple moving coordinates. On the contrary, in a formation regulation problem, it is not necessary since small perturbations from the nominal condition, in which the vehicles are in formation, are considered. A common origin is also not necessary if the relative distance to neighbors or a leader is used for regulation. Under these circumstances, the system theoretic control algorithms are applicable to a formation regulation problem where the vehicle models have six degrees of freedom. We will use a realistic six-degree-of-freedom model and investigate stability of a fleet using results from decentralized control theory. We will show that the leader-follower control algorithm does not have any unstable fixed modes if the followers are able to measure distance to the leader. We also show that the leader-follower control algorithm has fixed modes at the origin, indicating that the formation is marginally stable, when the relative distance measurements are not available. Multi-vehicle simulations are performed using a hybrid leader-follower control algorithm where each vehicle is given a desired trajectory to follow and adjusts its velocity to maintain a prescribed distance to the leader. Each vehicle is modeled as a three-degree-of-freedom system to investigate the vehicle’s motion in a horizontal plane. The examples show efficacy of the analysis.
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10

Kumar, Vimal, and Marius Paraschivoiu. "Self-Adaptive Upwinding for Large Eddy Simulation of Cross-Flow Jets." In ASME 2010 3rd Joint US-European Fluids Engineering Summer Meeting collocated with 8th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2010. http://dx.doi.org/10.1115/fedsm-icnmm2010-30736.

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A self-adaptive upwinding method for large eddy simulation (LES) has been describe in cross-flow in jets. The method is an extension of an existing Reynolds-averaged Navier–Stokes (RANS) code to an LES code by adjusting the contribution of the upwinding term to the convective flux. This adjustment is essentially controlled by reducing the upwind contribution in Roe MUSCL scheme. For the comparison of flow profiles obtained from the self-adaptive upwind LES code the experimental measurements of Andreopoulos and Rodi [1] are considered. The jet-to-cross-flow velocity ratio considered is 0.5 at a Reynolds number of 20,500 based on the jet bulk velocity and the jet diameter. In general, a reasonable agreement with the measurements is obtained. However, an intense backflow near the flat wall is observed. Further a vortex formation is observed behind at a distance of 0.6D from the jet axis.
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