Academic literature on the topic 'Radian angle measure'
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Journal articles on the topic "Radian angle measure"
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Clayton, David G. "A Trigonometrical Ratio to Replace the Dimensionless Angle in Radians." International Journal of Mechanical Engineering Education 38, no. 2 (April 2010): 132–34. http://dx.doi.org/10.7227/ijmee.38.2.4.
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Equations for use with SI radian units have the option of showing the radian unit or not. When the radian is not shown, identical purely numerical values for angles (θ) are produced in each equation. This is the common procedure. When the radian is shown, not all the θ values can show a radian unit: some must remain as pure numbers. This procedure is used whenever convenient, usually for extra clarity. The article proposes that the constantly numerical values of θ be treated as trigonometrical ratios, currently recognised as the ‘radian measure’ or the ‘circular measure’ (abbreviated: circ) of angles, and replaced by ‘circ θ’. This measure equals the length ratio (subtended arc/radius) for an angle θ at the circle centre. By this means the need for the dimensionless version of ‘angle in radians’ vanishes. In fact even dimensional angles in radians need not be used, because ‘circ θ’ allows any angle units to be used for θ.
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Alyami, Hanan. "A Radian Angle Measure and Light Reflection Activity." Mathematics Teacher: Learning and Teaching PK-12 115, no. 6 (June 2022): 422–31. http://dx.doi.org/10.5951/mtlt.2021.0217.
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During a Desmos activity, students adjust the measures of angles in radians to reposition a laser and a mirror so the beam passes through three stationary targets. The Radian Lasers activity can be extended to simulate project-based learning.
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Eggleton, Patrick J. "Experiencing Radians." Mathematics Teacher 92, no. 6 (September 1999): 468–71. http://dx.doi.org/10.5951/mt.92.6.0468.
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As Einstein stated, most fundamental concepts in science, including mathematics, are essentially simple. Students do not have to memorize and us radian measure without understanding the concept. The simple correspondence between the radial angle and the measure of its arc to the measuring of fractional parts of a wheel in terms of the number of spokes furnishes a concrete representation of the concept of radians.
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Grötschel, Martin, Harald Hanche-Olsen, Helge Holden, and Michael P. Krystek. "On Angular Measures in Axiomatic Euclidean Planar Geometry." Measurement Science Review 22, no. 4 (May 14, 2022): 152–59. http://dx.doi.org/10.2478/msr-2022-0019.
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Abstract We address the issue of angular measure, which is a contested issue for the International System of Units (SI). We provide a mathematically rigorous and axiomatic presentation of angular measure that leads to the traditional way of measuring a plane angle subtended by a circular arc as the length of the arc divided by the radius of the arc, a scalar quantity. We distinguish between the angular magnitude, defined in terms of congruence classes of angles, and the (numerical) angular measure that can be assigned to each congruence class in such a way that, e.g., the right angle has the numerical value π 2 {\pi \over 2} . We argue that angles are intrinsically different from lengths, as there are angles of special significance (such as the right angle, or the straight angle), while there is no distinguished length in Euclidean geometry. This is further underlined by the observation that, while units such as the metre and kilogram have been refined over time due to advances in metrology, no such refinement of the radian is conceivable. It is a mathematically defined unit, set in stone for eternity. We conclude that angular measures are numbers, and the current definition in SI should remain unaltered.
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Giniotis, Vytautas, Mindaugas Rybokas, and Petras Petroškevičius. "INVESTIGATIONS INTO THE ACCURACY OF ANGLE CALIBRATION." Geodesy and cartography 30, no. 3 (August 3, 2012): 65–70. http://dx.doi.org/10.3846/13921541.2004.9636644.
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Technical possibilities to create equipment for the calibration of flat angles are discussed in the article. The angular standard measure, the radian, has not been realised as a standard unit until now. Nevertheless, the unit of angular measure in degrees is used as the geometric measure of length in geodesy, machine engineering and other branches of industry – by multiangular prisms – polygons with an autocollimator, rotary tables, circular scales, etc. It should be noted that these angle measures are calibrated against the upper level measures (etalons) only at the several intervals depending on the number of sides (angles) of the polygon or the other standard measure. The methods of calibration of constant angle value in full circle are used as well. At the same time geodetic instruments, rotary tables of metal cutting tools and instruments, rotary encoders have a great number of discrete values. These values between the calibrated points remain unknown during calibration. The information received during calibration relative to all the information available can be evaluated using information entropy. The equipment of calibration permitting to select significantly more information would be essential for better accuracy assurance of instruments used in machine engineering, geodesy, building structures. Theoretical and technical background for justifying and developing such equipment for angular accuracy calibration is presented here. A modern scientific and technical background validates this concept.
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Alyami, Hanan. "Textbook representations of radian angle measure: The need to build on the quantitative view of angle." School Science and Mathematics 120, no. 1 (January 2020): 15–28. http://dx.doi.org/10.1111/ssm.12380.
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CUI, PENG, and XINGHUA ZHU. "SURGE GENERATION IN RESERVOIRS BY LANDSLIDES TRIGGERED BY THE WENCHUAN EARTHQUAKE." Journal of Earthquake and Tsunami 05, no. 05 (December 2011): 461–74. http://dx.doi.org/10.1142/s1793431111001194.
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Landslides can result in rocks and soil falling into reservoir at high velocity, thereby triggering large surface waves, which may threaten navigation vessels, dam stability, and lives and properties along the shore. This paper presents the results of an experimental study into surges caused by landslides entering reservoirs. First, eight factors — water depth, sliding impact velocity, slide volume, slide width, slide thickness, the mass of the slide blocks, sliding slope, and drop height of the mass center — were chosen as key parameters. Then, these were combined into four dimensionless factors: Froude number for sliding velocity, landslide scale, slide thickness and slide impact angle (radian measure). In addition, based on data from 145 model tests, empirical equations for prediction of the first and second impulsive wave heights were developed through nondimensional multiple linear regression analysis. These equations were applied to landslides triggered by the Wenchuan Earthquake along the shore of Zipingpu Reservoir. The calculated results were found to be in good agreement with field surveys and with calculations by other formulas; the proposed formula is believed preferable in that it incorporates dimension parameters and slope of the sliding surface.
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Johnson, Nick A., Rachel Dias, and Joseph J. Dias. "Scaphoid alignment in dorsally displaced distal radial fracture: a radiographic study." Journal of Hand Surgery (European Volume) 46, no. 6 (January 14, 2021): 600–606. http://dx.doi.org/10.1177/1753193420983696.
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We aimed to establish if fracture reduction will correct scapholunate angle in dorsally displaced distal radial fractures and to identify the relationship with other measures of distal radial position and carpal alignment. Radiographs of 131 patients with a distal radial fracture and of 50 patients with normal radiographs were reviewed. We measured the scapholunate, radiolunate, capitolunate and metacarporadial angles on the lateral views. Linear regression modelling showed that all parameters measured were significantly associated with scapholunate angle on the first radiograph following injury. Scapholunate angle increased following distal radial fracture. Reduction of the fracture improved scapholunate angle, and this was most strongly related to change in dorsal tilt. We conclude that scaphoid flexion is likely to compensate for the dorsal tilt of the lunate as an attempt to counter its dorsal tilt, and to stabilize the wrist to maintain hand function. Level of evidence: IV
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Tong, Junfei, Pengfei Dong, Sachin Kedar, Deepta Ghate, and Linxia Gu. "Three-dimensional shape analysis of peripapillary retinal pigment epithelium-basement membrane layer based on OCT radial images." Nanotechnology Reviews 10, no. 1 (January 1, 2021): 453–64. http://dx.doi.org/10.1515/ntrev-2021-0035.
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Abstract The peripapillary retinal pigment epithelium-basement membrane (ppRPE/BM) layer angle was recently proposed as a potential index for estimating intracranial pressure noninvasively. However, the ppRPE/BM layer angle, measured from the optical coherence tomography (OCT) scans, varied across the radial directions of the optic disc. This made the ppRPE/BM layer angle difficult to be utilized in its full potential. In this study, we developed a mathematical model to quantify the ppRPE/BM layer angles across radial scans in relation to the ppRPE/BM 3D morphology in terms of its 3D angle and scanning tilt angles. Results showed that the variations of the ppRPE/BM layer angle across radial scans were well explained by its 3D angle and scanning tilt angles. The ppRPE/BM layer 3D angle was reversely fitted from the measured ppRPE/BM layer angles across radial directions with application to six eyes from four patients, who underwent medically necessary lumbar puncture. The fitted curve from our mathematical model matched well with the experimental measurements (R 2 > 0.9 in most cases). This further validated our mathematical model. The proposed model in this study has elucidated the variations of ppRPE/BM layer angle across 2D radial scans from the perspective of the ppRPE/BM layer 3D morphology. It is expected that the ppRPE/BM layer 3D angle developed in this study could be further exploited as a new biomarker for the optic disc.
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Anagnost, Susan E., Richard E. Mark, and Robert B. Hanna. "S2 Orientation of Microfibrils in Softwood Tracheids and Hardwood Fibers." IAWA Journal 26, no. 3 (July 15, 2005): 325–38. http://dx.doi.org/10.1163/22941932-02603004.
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In this study the soft-rot method was applied to measuring the variation of microfibril angle (mfa) in loblolly pine, black cherry, sugar maple and canelo. For loblolly pine and black cherry, measurements of the radial wall indicated a gradual decrease in mfa across the earlywood portion of the growth ring, with an abrupt decrease at the latewood zone for pine, and in contrast only a slight decrease in microfibril angle across an annual ring of black cherry. In loblolly pine microfibril angle measurements indicated that the average microfibril angle in radial sections was very similar to the average for tangential sections of the same block. The average microfibril angles in the intermediate plane, or cell corner, were statistically similar to that of the tangential and radial plane, for pine, cherry, and maple. In canelo, microfibril angles in radial sections were significantly larger than in tangential and intermediate sections. In pine latewood the microfibril angles were less than the average mfa for the entire ring, and the earlywood microfibril angles were greater than the average mfa of the entire ring, thus the average mfa for the growth ring did not represent actual measured mfa values.
Books on the topic "Radian angle measure"
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International Association of Fire Chiefs., ed. Exam prep: Technical rescue : high angle. Sudbury, Mass: Jones and Bartlett, 2008.
Find full textBook chapters on the topic "Radian angle measure"
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Gjonaj, Erion, Yun Ouedraogo, and Sebastian Schöps. "Modelling of Droplet Dynamics in Strong Electric Fields." In Fluid Mechanics and Its Applications, 107–25. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09008-0_6.
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AbstractWe describe a modelling approach for the simulation of droplet dynamics in strong electric fields. The model accounts for electroquasistatic fields, convective and conductive currents, contact angle dynamics and charging effects associated with droplet breakup processes. Two classes of applications are considered. The first refers to the problem of water droplet oscillations on the surface of outdoor high-voltage insulators. The contact angle characteristics resulting from this analysis provides a measure for the estimation of the electric field inception thresholds for electrical discharges on the surface. The second class of applications consists in the numerical characterization of electrosprays. Detailed simulations confirm the scaling law for the first electrospray ejection and, furthermore, provide insight on the charge-radius characteristics for transient as well as steady state electrosprays.
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Brock, Fred V., and Scott J. Richardson. "Solar and Earth Radiation." In Meteorological Measurement Systems. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195134513.003.0012.
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This chapter is concerned with the measurement of solar radiation that reaches the earth’s surface and with the measurement of earth radiation, the long wave band of radiation emitted by the earth. The unit of radiation used in this chapter is the Wm-2. Table 10-1 lists some conversion factors. Radiant flux is the amount of radiation coming from a source per unit time in W. Radiant intensity is the radiant flux leaving a point on the source, per unit solid angle of space surrounding the point, in W sr-1 (sr is a steradian, a solid angle unit). Radiance is the radiant flux emitted by a unit area of a source or scattered by a unit area of a surface in Wm-2 sr-1. Irradiance is the radiant flux incident on a receiving surface from all directions, per unit area of surface, in Wm-2. Absorptance, reflectance, and transmittance are the fractions of the incident flux that are absorbed, reflected, or transmitted by a medium. Global solar radiation is the solar irradiance received on a horizontal surface, Wm-2. This is the sum of the direct solar beam plus the diffuse component of skylight, and is the physical quantity measured by a pyranometer. Direct solar radiation is the radiation emitted from the solid angle of the sun’s disc, received on a surface perpendicular to the axis of this cone, comprising mainly unscattered and unreflected solar radiation in Wm-2. At the top of the atmosphere this is usually taken to be 1367 W m-2 ± 3% due to changes in the earth orbit and due to sunspots. The direct beam is attenuated by absorption and scattering in the atmosphere. The direct solar radiation at the earth’s surface is the physical quantity measured by a pyrheliometer. Diffuse solar radiation (sky radiation) is the downward scattered and reflected radiation coming from the whole hemisphere, with the exception of the solid angle subtended by the sun’s disc in Wm-2. Diffuse radiation can be measured by a pyranometer mounted in a shadow band, or it can be calculated using global solar radiation and direct solar radiation.
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Dwyer, Michael. "Diphtheria ‘Arrives’." In Strangling Angel, 32–50. Liverpool University Press, 2018. http://dx.doi.org/10.5949/liverpool/9781786940469.003.0003.
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Chapter two will discuss how, from the 1880s, diphtheria increasingly became an urban disease in Britain, Europe and America, and it is unlikely that Irish urban centres managed to avoid this ominous trend. The introduction of the Infectious Disease (Ireland) Act in 1906, and the mandatory obligation this legislation placed on local authorities to notify outbreaks of infectious disease, exposed the true prevalence of diphtheria in Ireland. The burgeoning, albeit reluctant, acknowledgement by local authorities in Dublin and Cork that diphtheria was endemic in their districts brought with it realization that a comprehensive public health response was required. Radical reform of public health administration and service provision in the newly independent Irish Free State, meant that Irish health authorities were well placed to take advantage of cutting edge laboratory-based measures to control infectious disease. It examines the development of anti-diphtheria antitoxin and its application as a preventive measure on a mass scale in New York in the early 1920s before considering how this radical public health intervention was received by health authorities and medical professionals in Britain and Ireland. This chapter will show how Irish health officials and medical officers eschewed the reticence of their British counterparts, readily abandoned traditional sanitarian approaches to disease control and embraced new public health methodologies in a bid to protect child life.
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"Tables of Integrals††All angles are measured in radians." In Multivariable Calculus, Linear Algebra, and Differential Equations, A37—A47. Elsevier, 1986. http://dx.doi.org/10.1016/b978-0-12-304380-1.50023-3.
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Moid, Sana. "Taxation Policy Measures for E- Retailers." In Advances in E-Business Research, 276–90. IGI Global, 2016. http://dx.doi.org/10.4018/978-1-4666-9921-2.ch015.
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The internet has already revolutionized many aspects of modern business and living and promises to bring even more radical future changes. In contrast, tax laws are normally slow to changing realities. It is anticipated that trade in tangible (physical) goods with e- commerce will not introduce problems. However, trade in intangible (electronic or digital) goods can be problematic because they will be difficult if not impossible to track. The chapter discusses the important concepts woven around the idea of taxing e tailing transactions and aims at coming up with a conclusion which will help further to determine the appropriate tax policies for e retailers keeping in mind the global framework. The chapter aims at discussing the concept of Internet Taxation, E- Retailing laws and regulations in Global Context. The chapter also discusses broad outlines relating to taxability of E Retailing transactions from VAT and CST angle under different scenarios and arguments in favor and against of taxing the e tailing transactions. The chapter also discusses important acts passed in different economies for taxing online retailers including Marketplace Fairness Act 2013 and Internet Tax Freedom Act. It is concluded by discussing the possible effects of the online retail tax. It could be argued that e- commerce for most part will not require new tax principles. Existing principles still apply only the old ways of doing things need to be digitized. The internet and e- commerce certainly does introduce some new business models and products that would not have been possible with old technology. And in some case, new laws may be required or old laws amended. Trade in intangibles or goods that are in digital format promises to be the main problem area.
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"Practical procedures." In Oxford Handbook for Medical School, edited by Kapil Sugand, Miriam Berry, Imran Yusuf, Aisha Janjua, Chris Bird, David Metcalfe, Harveer Dev, et al., 821–38. Oxford University Press, 2019. http://dx.doi.org/10.1093/med/9780199681907.003.0045.
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This chapter gives clear guidance on practical procedures which most medical students would be expected to be competent at by the end of their training. The beginning of the chapter advises on the importance of strict hand hygiene in protecting patients from unnecessary infection. The chapter also explains how to measure blood pressure manually. Advice is given on how to place a nasogastric tube and how to place a urethral catheter, with radiographs and illustrations to help clarify anatomy and ensure against false passage. Clear advice is given on how to set up for and perform both venepuncture and intravenous cannulation, with advice on common anatomical sites for these procedures, contraindications, and first aid for needle-stick injuries. For emergencies, interosseous access is also discussed. How to obtain an arterial blood gas is explained, including the Allen test to ensure adequate ulnar arterial blood flow if sampling from the radial artery. The chapter also explains how to measure the ankle–brachial pressure index and basic plastering. Adequate supervision by senior staff is emphasized throughout.
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"Powder X-ray Diffraction." In Pharmaceutical Crystallography: A Guide to Structure and Analysis, 168–93. The Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/bk9781782629665-00168.
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Powder X-ray diffraction is an essential partner to single-crystal X-ray diffraction because it is applied to a bulk solid rather than a selected single crystal. Powder diffraction can be viewed as a collection of simultaneous single-crystal measurements from a large number of crystals in all orientations. Averaging of the sample means that the diffracted beams are distributed around cones with half-angle 2θ, which appear as rings when measured on a 2-D detector. If the sample orientation is properly averaged, the diffracted intensity is spread uniformly around the rings so it is necessary only to scan along a radius to produce a representative plot of diffracted intensity vs. 2θ. Powder diffraction can be measured in transmission geometry, where the incident beam passes through the sample, or in reflection geometry, where the incident beam appears to be reflected from the surface of the sample. The relationship between a crystal structure and its powder diffraction pattern is described and some applications of powder diffraction for pharmaceutical solids are considered.
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Potter, Simon J. "Fraternizing in the Ether, 1931–1933." In Wireless Internationalism and Distant Listening, 50–83. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198800231.003.0003.
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During the early 1930s faith in a utopian form of wireless internationalism was shaken by the world economic crisis, the Japanese invasion of Manchuria, and the Nazi revolution in Germany. Radio still seemed a potential means to encourage international understanding and peace, but increasingly it also appeared to be a powerful tool of propaganda that might serve aggressive nationalist ends. As Europe’s broadcasting infrastructure became more formidable, broadcasters continued to work through the International Broadcasting Union to regulate the airwaves and combat interference and hostile propaganda. These measures were only partially effective and were ignored by a powerful new station broadcasting commercial programmes across Europe in several languages, Radio Luxembourg. The League of Nations also began to study the disruptive impact of radio on international affairs, and established its own broadcasting station, Radio Nations. Relay work continued, linking up the broadcasters of Europe and forging new connections across the Atlantic. The number of short-wave broadcasters increased significantly during this period, and the BBC established its own short-wave Empire Service, designed to reach out to white expatriate listeners in Britain’s colonies, and to English speakers in the ‘dominions’. Many in the US could also tune in, and British civil servants, notably at the Foreign Office, worried about the impact on Anglo-American relations.
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Bunker, Bruce C., and William H. Casey. "The Structure and Properties of Water." In The Aqueous Chemistry of Oxides. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780199384259.003.0008.
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Water is one of the most complex fluids on Earth. Even after intense study, there are many aspects regarding the structure, properties, and chemistry of water that are not well understood. In this chapter, we highlight the attributes of water that dictate many of the reactions that take place between water and oxides. We start with a single water molecule and progress to water clusters, then finally to extended liquid and solid phases. This chapter provides a baseline for evaluating what happens when water encounters simple ions, soluble oxide complexes called hydrolysis products, and extended oxide phases. The primary phenomenon highlighted in this chapter is hydrogen bonding. Hydrogen bonding dominates the structure and properties of water and influences many water–oxide interactions. A single water molecule has eight valence electrons around a central oxygen anion. These electrons are contained in four sp3-hybridized molecular orbitals arranged as lobes that extend from the oxygen in a tetrahedral geometry. Each orbital is occupied by two electrons. Two of the lobes are bonded to protons; the other two lobes are referred to as lone pairs of electrons. The H–O–H bond angle of 104.5° is close to the tetrahedral angle of 109.5°. The O–H bond length in a single water molecule is 0.96 Ǻ. It is important to recognize that this bond length is really a measure of the electron density associated with the oxygen lone pair bonded to the proton. This is because a proton is so incredibly small (with an ionic radius of only 1.3·10−5 Ǻ) that it makes no contribution to the net bond length. The entire water molecule has a hard sphere diameter of 2.9 Ǻ, which is fairly typical for an oxygen anion. This means the unoccupied lone pairs are distended relative to the protonated lone pairs, extending out to roughly 1.9 Ǻ. The unequal distribution of charges introduces a dipole within the water molecule that facilitates electrostatic interactions with other molecules.
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Jha, Pankaj, and Ke Wu. "Orbital Angular Momentum Wave and Propagation." In Recent Microwave Technologies [Working Title]. IntechOpen, 2022. http://dx.doi.org/10.5772/intechopen.104477.
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Orbital angular momentum (OAM) techniques are exploited for a wide range of potential radiofrequency (RF) and electromagnetic applications, including megahertz-through-terahertz wireless systems, fiber-based and free-space optical communications and sensing, just like acoustic and any other wave-based counterparts. In those RF and electromagnetic applications, OAM wave is set to enable the development of high-speed and high-capacity communications, radar imaging, and sensing systems, among many others. In this chapter, a comprehensive comparison between plane wave and OAM wave propagation using a patch antenna as a radiator at 2.45 GHz is presented and discussed. This comparison allows the appreciation of the fundamental properties of the OAM wave when compared against its plane wave counterpart. For simplified comparison and discussion, we will use two abbreviated terms: PWPA for plane-wave patch antenna and OWPA for OAM wave patch antenna. PWPA refers to as planar patch antenna that produces plane waves in far-field, whereas patch antenna that delivers OAM waves in far-field is termed as OWPA. In this context, all physical quantities for wave propagation such as electric field, magnetic field, wave impedance, wave vector, velocity, pitch, and propagation constant are theoretically studied for OAM waves and compared with plane waves. First, OAM wave generation is studied through widely used uniform circular antenna array (UCAA) in literature. Then, plane wave patch antenna (PWPA) and OAM wave patch antenna (OWPA) are designed and verified through simulation and measurement. OWPA is designed with characteristic mode analysis (CMA) based on a lossy substrate to excite a twisting wave at a determined patch location. With this in mind, a comparative investigation of PWPA and OWPA is conducted for different physical parameters. Cylindrical near-field scan clearly shows a helical wave motion for OWPA, whereas a normal plane wave motion for PWPA. Furthermore, the comparison of plane wave and OAM wave propagation is demonstrated using the combination of a Tx–Rx antenna pair. It is observed that the overall signal from OWPA can be received with two PWPAs at an angle as OWPA has a dispersive beam. Moreover, the receiving antenna with a large aperture and plane wave horn antenna (PWHA) in the line of sight (LOS) range can also be used to receive the overall signal from OWPA. The received signal in PWPA–PWPA, OWPA–OWPA, OWPA–PWPA–PWPA, OWPA–PWHA Tx–Rx pairs is thoroughly compared and studied. Measured and simulated results for transmission are −30 dB for 0 dB input signal in OWPA–PWPA–PWPA and OWPA–PWHA cases, which are reasonably justified within the sensitivity/dynamic range of short-distance communication and radar sensing receivers.
Conference papers on the topic "Radian angle measure"
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Tomita, Eiji, Nobuyuki Kawahara, and Yasuji Toda. "In Situ Measurement of Water Temperature With a Sensor Using Interferometry." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32022.
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It is very important to measure fluid temperature in research and industrial fields. However, there are no devices with high-response measurement. In this study, a sensor system is proposed to measure the temperature with very high response using interferometry. The sensor for temperature measurement utilizes the difference in measurement length between two laser beams. Both are the test beams, and there is no reference beam. The two beams pass mostly through closely arranged paths; therefore, the effect of mechanical vibration on the two test beams is expected to be very small. The laser beam was introduced through a selfoc micro lens (SML) into a polarization-maintaining fiber connected with a sensor part. The beam emitted from another SML was divided into two. Both beams enter a quartz block and are reflected at the corner to change direction by an angle of a quarter pai radian. They then pass through the test section although the lengths of the two beams are different in the measurement region. This sensor was installed on a side wall of a vessel. Water was poured into the vessel and stirred with a hot magnetic stirrer. The temperature near the sensor was also measured with a thermocouple as a reference. This paper focuses on the confirmation and evaluation of this system of temperature measurement. When the direction of the fringe shift with two photo-detectors was judged, the direction of the temperature could be distinguished. One feature of this sensor is that it minimizes the effect of the thermal boundary layer. If the condition of the fluid near the test section is uniform, both beams have almost the same boundary layers. Then, both thermal boundary layers are expected to be cancelled because the length of the test section is the difference between both beams. As a result, it was confirmed that this sensor system is useful for detecting changes in water temperature.
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Kopp, Gregory A., and Robert J. Martinuzzi. "The Measurements of Mean Flow Angles Between an Automotive Fan and Stator." In ASME 2002 Joint U.S.-European Fluids Engineering Division Conference. ASMEDC, 2002. http://dx.doi.org/10.1115/fedsm2002-31431.
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Measurements of the mean velocity vector were conducted to determine the exit angle from an automotive engine cooling fan module. The measurements were made at 15 locations along a radius between the hub and the band. The radius investigated was located in a plane roughly half-way between the blade trailing edge and stator leading edge. A two-component laser Doppler velocimeter and a four-wire hot-wire probe were used to measure the flow fields. It was found that the results obtained from hot-wire anemometry will have significant bias errors when used to measure the velocity vectors between the fan and the stator unless phase-averaged data are obtained with the probe re-oriented by phase. The differences between the techniques occur because the distribution of instantaneous swirl angles is bi-modal. Further, the mean flow angle is close to a local minimum in the probability density function of the swirl angle. This will act to increase errors in measurement devices whose accuracy depends on flow direction (the quantity being measured) such as five-hole probes which are used in industry.
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Meuleman, Corine, Frank Willems, Rick de Lange, and Bram de Jager. "Surge in a Low-Speed Radial Compressor." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-426.
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Surge is measured in a low-speed radial compressor with a vaned diffuser. For this system, the flow coefficient at surge is determined. This coefficient is a measure for the inducer inlet flow angle and is found to increase with increasing rotational speed. Moreover, the frequency and amplitude of the pressure oscillations during fully-developed surge are compared with results obtained with the Greitzer lumped parameter model. The measured surge frequency increases when the compressor mass flow is throttled to a smaller flow rate. Simulations show that the Greitzer model describes this relation reasonably well except for low rotational speeds. The predicted amplitude of the pressure rise oscillations is approximately two times too small when deep surge is met in the simulations. For classic surge, the agreement is worse. The amplitude is found to depend strongly on the shape of the compressor and throttle characteristic, which are not accurately known.
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Kao, Yi-Huan, Samir B. Tambe, and San-Mou Jeng. "Effect of Dome Geometry on Swirling Flow Field Characteristics of a Counter-Rotating Radial-Radial Swirler." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95344.
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An experimental study has been conducted to study the effect of the dome geometry on the aerodynamic characteristics of a non-reacting flow field. The flow was generated by a counter-rotating radial-radial swirler consisting of an inner, primary swirler generating counter-clockwise rotation and an outer, secondary swirler generating clockwise rotation. The dome geometry was modified by introducing dome expansion angles of 60° and 45° with respect to the swirler centerline, in addition to the baseline case of sudden expansion (90°). The flow downstream of the swirler is confined by a 50.8mm × 50.8mm × 304.8mm (2″ × 2″ × 12″) plexiglass chamber. A two-component laser doppler velocimetry (LDV) system was used to measure the velocities in the flow field. The dome geometry is seen to have a clear impact on mean swirling flow structure near the swirler exit rather than the downstream flow field. For the configurations with 60° and 45° expansion, no corner recirculation zone is observed and the swirling flow structure is asymmetric due to the non-axisymmetric dome geometry. The cross-section area of central recirculation zone is larger for dome geometry with 60° expansion angle, as compared to the 90° and 45° cases. The configurations with 60° and 45° expansion have higher magnitudes of negative velocity inside the core of central recirculation zone, as compared to the configuration with 90° expansion angle.
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Tempelis, Andreas, Matthew Jussaume, and Julie Ann Jackson. "Comparison of measured and predicted bistatic scattering from a right-angle dihedral." In 2011 IEEE Radar Conference (RadarCon). IEEE, 2011. http://dx.doi.org/10.1109/radar.2011.5960515.
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Sipos, G. "Secondary Flow and Loss Distribution in a Radial Compressor With Untwisted Backswept Vanes." In ASME 1990 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1990. http://dx.doi.org/10.1115/90-gt-161.
Full textAbstract:
The unshrouded impeller and the vaneless diffuser of a single-stage radial compressor have been investigated at three flow rates. Three-dimensional velocities and pressures were measured at a tip speed of 84 m/s by an L2F-velocimeter, a slanted single hot-wire probe and piezoresistive pressure transducers. The measurements show that upstream the blading the averaged meridional inlet flow angle is about 54 degree and a periodical variation of the meridional flow angle of about 25 degree occurs near the casing wall. Further, an inlet vortex of clockwise direction appears and an initial whirl is induced. The specific work of the initial whirl corresponds to approximately 12% of the enthalpy losses between inlet pipe and diffuser outlet. In the beginning of the passage, the inlet vortex is suppressed and a solid body vortex of counterclockwise direction can be observed. At the outlet, a heavy flow deceleration at the blade suction side with subsequent separation can be seen. Increasing the flow rate decreases the wake and causes a more uniform loss distribution in this area. The measured secondary vortex flow and rotary stagnation pressure gradients are compared with test results from impellers with inducer. The incidence of the investigated impeller is greater than that of the impellers with inducer, but the wake-jet outlet flows are very similar. Inlet losses could be reduced by improving incidence angles by matching the blade angles to the inlet flow angles. Smaller blade angles at the shroud would reduce or eliminate separation at the leading edge, and the resulting reduction in low momentum fluid along the suction surface would help to avoid separation on that surface near the outlet.
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Brizuela, Edward A. "A Contribution to the Study of Exit Flow Angle in Radial Turbines." In ASME 1991 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1991. http://dx.doi.org/10.1115/91-gt-010.
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The emergence and evolution of relative whirling motions in the exducer region of an Inward Flow Radial Turbine is discussed. Existing models of relative motion are reviewed and expanded by consideration of the effect of centrifugal forces differences arising from velocity gradients. It is shown that the often observed phenomenon of outlet overturn/underturn is inherent to the use of straight-helix exducers. Explicit mathematical relationships between exit velocities and radius are not available. If, however, such relationships could be considered linear, it is shown that two new reference radii may be identified such that the net outlet properties can be measured or computed at these locations as lump parameters. These radii are different from the often used hydraulic radius. The new models and reference radii are verified using published experimental data.
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Kassens, I., and M. Rautenberg. "Flow Measurements Behind the Inlet Guide Vane of a Centrifugal Compressor." In ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-086.
Full textAbstract:
In a centrifugal compressor adjustable inlet guide vanes (IGV) in front of the impeller are used to regulate the pressure ratio and the mass flow. The stationary measurement of the velocity profile in front of the impeller with different angles of the IGV displays shock losses at the inlet edge of blade of the impeller. In the partial-load region (e.g. partial-load efficiency) the radial distribution of the flow influences considerably the performance of the impeller. The tested compressor consists of an adjustable IGV with straight vanes, a shrouded impeller and a vaneless, parallel diffuser. In the first measurement location, behind the IGV, total pressure, static pressure and flow angle were measured with a 5-hole cylinder probe. In the second measurement location, in front of the impeller, the measurement of the total pressure was carried out with a Kiel probe and the flow angle with a Cobra probe accordingly the static wall pressure was measured. Taking into consideration the fundamental thermodynamical equations it was possible to determine the velocity profiles because of the measured distributions of the flow angle in these two measurement locations. For different angles of the IGV and with various mass flows the distributions of the deflection defect behind the IGV are described. Starting with the measured distributions of the flow in front of the impeller the flow angles at the impeller inlet are calculated and the distributions of the incidence angle at the impeller inlet are figured out.
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Brown, Neal A. "Unique Calibration of a "5-hole" Pitot Rake and Application for Wake Survey." In SNAME 25th American Towing Tank Conference. SNAME, 1998. http://dx.doi.org/10.5957/attc-1998-030.
Full textAbstract:
A rake of five “5-hole" directional Pitot tubes (actually "6-hole" because static taps are included) was calibrated for angular sensitivity, as well as velocity, in a towing tank. This was; accomplished by deploying the rake on a tubular shaft out of the bow of a propeller boat. Combinations of propeller boat yaw angle and rotation angle of the rake shaft provided a full and systematic coverage of flow angles in tangential and radial planes of each probe. Thirty single ended pressure transducers were used, one for each hole in each of five probes, to measure pressures. The transducers resided below the waterline, making air purging practical. Calibration required forty one runs.
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Shreeve, R. P., H. D. Schulz, J. R. Erwin, and L. Schumann. "A Novel Centrifugal Diffuser Test Device." In ASME 1985 Beijing International Gas Turbine Symposium and Exposition. American Society of Mechanical Engineers, 1985. http://dx.doi.org/10.1115/85-igt-135.
Full textAbstract:
A large scale (2 inch wide test vanes at 50-inch inlet diameter), low speed (100–200 ft/sec) steady flow radial cascade wind tunnel for diffuser studies was designed, built and tested. The apparatus was shown to provide flow angles from radial in the range 58–72 degrees with suitable spanwise profiles. The novel flow angle control mechanism was shown to work but measured flow angles were somewhat smaller than expected. The mechanism for controlling case-wall boundary layer profile did not behave as predicted. Attempts to predict the generated flow both analytically and with computational codes are compared with initial measurements. The low speed apparatus will be used to obtain detailed data for diffuser design and analysis code verification, and to provide experience toward the design of a high speed device.