Готові списки джерел за темами / Propagation

Зміст

  1. Статті в журналах
  2. Дисертації
  3. Книги
  4. Частини книг
  5. Тези доповідей конференцій
  6. Звіти організацій

Добірка наукової літератури з теми "Propagation"

Автор: Grafiati
Опубліковано: 4 червня 2021
Оновлено: 23 листопада 2024

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

Оберіть тип джерела:

Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Propagation".

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

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

Статті в журналах з теми "Propagation"

1

Zheng, Guoliang, Lili Wan, Tiefeng He, Qingyang Wu, and Xuhui Zhang. "The Propagation Characteristics of Circular Airy Beams with Propagational Fractional-Order Optical Vortices." Photonics 11, no. 1 (January 7, 2024): 64. http://dx.doi.org/10.3390/photonics11010064.

Повний текст джерела
Анотація:
We investigate the propagation properties of circular Airy beams (CABs) with propagational fractional-order optical vortices (OVs). The superposition of the phase singularity and polarization singularity from a vortex vector beam (VVB) plays a significant role in creating a propagational fractional vortex beam. Propagational fractional vortex beams can be considered as a superposition of left and right circularly polarized vortex beams with different integer topological charges (TCs). We study the propagation characteristics of two kinds of propagational fractional vortex CABs, and the results show that both of the two kinds of beams can stably propagate in free space, and they exhibit an “abruptly auto-focusing” property and “self-healing” property during the propagation. The intensity distribution of the first kind of propagational fractional vortex CAB has an odd number of petals (2m + 1), while the second kind of beam has a crescent-shaped intensity distribution. The influence of turbulence on the beam propagation through atmosphere under different turbulence strengths is also numerically studied in this paper. A fractional vortex CAB with an initial radius r0 = 10 mm can retain its shape after propagating 20 m when the atmospheric refractive-index structure constant CN2=0.2×10−12m−2/3. Our results are expected to broaden the application of CABs.
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Abrame, Andre, and Djamal Habet. "Handling All Unit Propagation Reasons in Exact Max-SAT Solvers." Proceedings of the International Symposium on Combinatorial Search 5, no. 1 (September 1, 2021): 2–9. http://dx.doi.org/10.1609/socs.v5i1.18313.

Повний текст джерела
Анотація:
Unit propagation (UP) based method are widely used in Branch and Bound (BnB) Max-SAT solvers for detecting disjoint inconsistent subsets (IS) during the lower bound (LB) estimation. UP consists in assigning to true (propagating) all the literals which appear in unit clauses. The existing implementations of UP only consider the first unit clause causing the assignment of each variable, thus the propagations must be done and undone chronologically to ensure that all the unit clauses are properly exploited. Max-SAT BnB solvers transforms the formulas to ensure IS disjointness. These transformations remove clauses from the formula thus propagations are frequently undone. Since the propagations are undone in chronological order, many useless unassignments and reassignments are performed. We propose in this paper a new unit propagation scheme which considers all the unit clauses causing the assignment of the variables by UP. This new scheme allows to undo propagations in a non-chronological way and thus it reduces the number of redundant propagation steps made by BnB solvers. We also show how the information available with this new scheme can be used to influence the characteristics of the IS built by BnB solvers. We propose a heuristic which aims at reducing their size, and thus improving the quality of the LB estimation. We have implemented the new propagation scheme as well as the IS building heuristic in our solver MSsolver. We present and discuss the results of the experimental study we have performed.
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Wang, Bin, Guosen Chen, and Fei Liu. "Diversity of the Madden-Julian Oscillation." Science Advances 5, no. 7 (July 2019): eaax0220. http://dx.doi.org/10.1126/sciadv.aax0220.

Повний текст джерела
Анотація:
Madden-Julian Oscillation (MJO) is the dominant mode of atmospheric intraseasonal variability and the cornerstone for subseasonal prediction of extreme weather events. Climate modeling and prediction of MJO remain a big challenge, partially due to lack of understanding the MJO diversity. Here, we delineate observed MJO diversity by cluster analysis of propagation patterns of MJO events, which reveals four archetypes: standing, jumping, slow eastward propagation, and fast eastward propagation. Each type exhibits distinctive east-west asymmetric circulation and thermodynamic structures. Tight coupling between the Kelvin wave response and major convection is unique for the propagating events, while the strength and length of Kelvin wave response distinguish slow and fast propagations. The Pacific sea surface temperature anomalies can affect MJO diversity by modifying the Kelvin wave response and its coupling to MJO convection. The results shed light on the mechanisms responsible for MJO diversity and provide potential precursors for foreseeing MJO propagation.
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Toutain, P. L., P. G. Marnet, M. P. Laurentie, R. Garcia-Villar, and Y. Ruckebusch. "Direction of uterine contractions during estrus in ewes: a reevaluation." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 249, no. 4 (October 1, 1985): R410—R416. http://dx.doi.org/10.1152/ajpregu.1985.249.4.r410.

Повний текст джерела
Анотація:
In four ewes direction of propagation of uterine contractions was evaluated using an electromyographic technique during 15 entire estrous periods; 120,101 propagations were analyzed. When horns were considered separately 89.9% of all propagations were classified into three main modes: ascending (34.3%), descending (59.85%), and divergent (5.85%). When both horns were analyzed simultaneously, horn's synchronicity was observed in most instances; on this basis, eight modes of propagation were identified of which three accounted for two-thirds of all propagation: synchronous descending (24.9%), reciprocal propagation (descending on one horn and then ascending on contralateral horn) (22.1%), and isolated descending propagation (18.0%). A time-dependent pattern of propagation throughout estrus was clearly identified, the percentage of ascending propagations reaching a minimum (16.5%) and the percentage of descending propagation reaching a maximum (77%) at peak uterine motility level. By considering both direction of uterine propagation and cervical mechanical activity, a new hypothesis concerning two aspects of sperm transport (speed and mechanism) was formulated. It is hypothesized that the high prevalence of descending propagations is important to reduce sperm cell population by selecting the most vigorous spermatozoa; such selection is possible when the mechanical cervical activity is low or absent (cervix open); when cervical mechanical activity is high (cervix closed), it is suggested that both descending and ascending propagations participate in sperm transport by back and forth motion of luminal fluid within the uterine lumen.
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Cohen, David, Christopher Jefferson, and Karen Petrie. "A Theoretical Framework for Constraint Propagator Triggering." Proceedings of the International Symposium on Combinatorial Search 7, no. 1 (September 1, 2021): 19–27. http://dx.doi.org/10.1609/socs.v7i1.18388.

Повний текст джерела
Анотація:
CSP instances are commonly solved by backtracking search combined with constraint propagation. During search, constraint solvers aim to remove any literals (variable-value pair) that can be shown not to be part of any solution. This literal removal, called propagation, is the beating heart of modern constraint solvers. A significant proportion of the runtime of propagating constraint solvers is spent running propagation algorithms. Therefore any mechanism for reducing how frequently propagators are called leads directly to significant performance improvements. One family of popular techniques is dynamic triggering — these techniques aim to avoid invoking a propagator when it would remove no literals. While this technique has been successful in practice, it has not yet been studied theoretically. This paper provides a theoretical framework for understanding when dynamic triggering will be successful. In particular, we prove when a literal deletion does not require a propagator to be executed. To achieve this, we describe supports: a support for a constraint is a set of literals whose presence in a search state ensures that propagating the constraint will not remove any literals. Therefore running the propagator when a literal outside the support is deleted is a waste of time. By characterising supports and giving a definition of dynamic and static supports for the CSP, we provide the framework for a proper analysis. We show how the number of triggers required for different constraints varies widely. For some constraints, dynamic triggering allows very small supports, for others the number of required supports is provably large.
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Stovas, Alexey, Yuriy Roganov, and Vyacheslav Roganov. "Interaction between P, S1 and S2 waves in multilayered periodic monoclinic media at low frequencies." Geophysical Journal International 220, no. 3 (December 5, 2019): 1947–55. http://dx.doi.org/10.1093/gji/ggz551.

Повний текст джерела
Анотація:
SUMMARY Application of the Floquet theorem and the matrix propagator method reduces the problem of the plane wave propagation in a periodically layered anisotropic media, to analysis of the properties of stationary envelopes of different wave modes propagating up- and downwards. We analyse the interchanging of stop- and pass-bands and their structure at low frequencies for a periodically layered medium with monoclinic symmetry. The analysis shows the effect of interaction between P,S1 and S2 wave multipliers for stop- and pass-band structure and gives insight into the wave propagation in vertically heterogeneous anisotropic media which is important in modelling and interpretation of seismic data.
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Kohles, S. S., J. R. Bowers, A. C. Vailas, and R. Vanderby. "Ultrasonic Wave Velocity Measurement in Small Polymeric and Cortical Bone Specimens." Journal of Biomechanical Engineering 119, no. 3 (August 1, 1997): 232–36. http://dx.doi.org/10.1115/1.2796085.

Повний текст джерела
Анотація:
A system was refined for the determination of the bulk ultrasonic wave propagation velocity in small cortical bone specimens. Longitudinal and shear wave propagations were measured using ceramic, piezoelectric 20 and 5 MHz transducers, respectively. Results of the pulse transmission technique were refined via the measurement of the system delay time. The precision and accuracy of the system were quantified using small specimens of polyoxymethylene, polystyrene-butadiene, and high-density polyethylene. These polymeric materials had known acoustic properties, similarity of propagation velocities to cortical bone, and minimal sample inhomogeneity. Dependence of longitudinal and transverse specimen dimensions upon propagation times was quantified. To confirm the consistency of longitudinal wave propagation in small cortical bone specimens (<1.0 mm), cut-down specimens were prepared from a normal rat femur. Finally, cortical samples were prepared from each of ten normal rat femora, and Young’s moduli (Eii), shear moduli (Gij), and Poisson ratios (vij) were measured. For all specimens (bone, polyoxymethylene, polystyrene-butadiene, and high-density polyethylene), strong linear correlations (R2 > 0.997) were maintained between propagation time and distance throughout the size ranges down to less than 0.4 mm. Results for polyoxymethylene, polystyrene-butadiene, and high-density polyethylene were accurate to within 5 percent of reported literature values. Measurement repeatability (precision) improved with an increase in the wave transmission distance (propagating dimension). No statistically significant effect due to the transverse dimension was detected.
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Kim, Hyo Jin, Sang Ho Lee, and Moon Kyum Kim. "Prediction of Crack Propagation under Dynamic Loading Conditions by Using the Enhanced Point Collocation Meshfree Method." Key Engineering Materials 324-325 (November 2006): 1059–62. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.1059.

Повний текст джерела
Анотація:
An efficient and accurate numerical program with enhanced point collocation meshfree method is developed to simulate crack propagation under dynamic loading conditions. The enhanced meshfree method with point collocation formulation and derivative approximation in solids is presented. This study also presents the crack propagation criterion and computation of propagating direction, and the total structure of the numerical program named PCMDYC(Point Collocation Meshfree method for DYnamic Crack propagation). Several examples of crack propagation under dynamic loads are analyzed to simulate the arbitrary crack propagation under dynamic loads. The results show that PCMDYC predicts the propagating path of crack under dynamic loading conditions accurately and robustly.
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Idol, Travis, Adel Youkhana, and Renier Paul Santiago. "Vegetative and micropropagation of leucaena." Tropical Grasslands-Forrajes Tropicales 7, no. 2 (May 31, 2019): 87–95. http://dx.doi.org/10.17138/tgft(7)87-95.

Повний текст джерела
Анотація:
Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.To effectively utilize sterile hybrids of leucaena, efficient protocols for vegetative propagation are needed that meet different user requirements and capabilities. We developed and compared methods for propagating several sterile hybrids of leucaena and compared them with each other and with propagation via seeds for variety K636. Methods included air-layers, rooted cuttings, grafting and tissue culture (micropropagation). All methods required 14‒20 weeks from generation of new shoots on the stock plant to production of rooted plantlets ready to outplant as compared with 6‒8 weeks for seedlings of K636. Successful rooting was highest for air-layers and rooted cuttings. Grafting had lower success owing to a higher skill requirement for the propagator. Tissue culture showed promise, but use of field-grown material was limited by microbial contamination of propagation media. Rooted cuttings are the best option presently for operational-scale propagation, but the method requires a mist system or a carefully controlled non-mist environment. If an effective method can be developed, grafting of young shoots onto a seedling rootstock is an alternative that retains the advantages of a seedling tap root and requires fewer resources than rooted cuttings or tissue culture.
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Hamabata, Hiromitsu, Tomikazu Namikawa, and Kazuhiro Mori. "The effect of lower-hybrid waves on the propagation of hydromagnetic waves." Journal of Plasma Physics 40, no. 2 (October 1988): 337–51. http://dx.doi.org/10.1017/s0022377800013313.

Повний текст джерела
Анотація:
Propagation characteristics of hydromagnetic waves in a magnetic plasma are investigated using the two-plasma fluid equations including the effect of lower-hybrid waves propagating perpendicularly to the magnetic field. The effect of lower-hybrid waves on the propagation of hydromagnetic waves is analysed in terms of phase speed, growth rate, refractive index, polarization and the amplitude relation between the density perturbation and the magnetic-field perturbation for the cases when hydromagnetic waves propagate in the plane whose normal is perpendicular to both the magnetic field and the propagation direction of lower-hybrid waves and in the plane perpendicular to the propagation direction of lower-hybrid waves. It is shown that hydromagnetic waves propagating at small angles to the propagation direction of lower-hybrid waves can be excited by the effect of lower-hybrid waves and the energy of excited waves propagates nearly parallel to the propagation direction of lower-hybrid waves.
Стилі APA, Harvard, Vancouver, ISO та ін.
Більше джерел

Дисертації з теми "Propagation"

1

Braunstein, Alfredo. "Survey propagation." Doctoral thesis, SISSA, 2004. http://hdl.handle.net/20.500.11767/4250.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Nechayev, Yuriy Ivanovich. "Investigations into propagation mechanisms for urban radiowave propagation modelling." Thesis, University of Birmingham, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420512.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Kubicek, Martin. "High dimensional uncertainty propagation for hypersonic flows and entry propagation." Thesis, University of Strathclyde, 2018. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=30780.

Повний текст джерела
Анотація:
To solve complex design problems, engineers cannot avoid to take into account the involved uncertainties. This is important for the analysis and design of hypersonic objects and vehicles, which have to operate in extreme conditions. In this work, two approaches for a high dimensional uncertainty quantification (UQ) are developed. The first approach performs a single-fidelity non-intrusive forward UQ, while the second one performs a multi fidelity UQ, as an extension of the first approach. Both methods are focused on real engineering problems and, therefore, appropriate heuristics are included to achieve an optimal trade-off between accuracy and computational costs. In the first approach, the stochastic domain is decomposed into domains of lower dimensionality, and, then, each domain is handled separately. This is possible due to the application of the HDMR, which is here derived in a new way. This new derivation allowed to deduce important conclusions about the high dimensional modelling, which are used in the prediction scheme. This novel approach for the selection of the higher order interaction effects drastically reduce the required number of samples. In order to have optimally distributed samples for the problem of interest, the adaptive sampling scheme is introduced. Moreover, the multi-surrogate approach is introduced in order to improve the robustness of the method. The single-fidelity approach is tested on a debris re-entry case and the method is validated with respect to the MC simulation method. In the second approach, the multi-fidelity approach has been developed. In order to have the optimal combination of the low fidelity models, the power ratio approach is introduced. To correct the low fidelity model, the classical additive correction, adapted to work within the HDMR approach, is used. The multi-fidelity approach has been tested on the GOCE re-entry case, where the performed tests demonstrate the potentialities of the method.
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Tu, Ronghui. "Generalized Survey Propagation." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19972.

Повний текст джерела
Анотація:
Survey propagation (SP) has recently been discovered as an efficient algorithm in solving classes of hard constraint-satisfaction problems (CSP). Powerful as it is, SP is still a heuristic algorithm, and further understanding its algorithmic nature, improving its effectiveness and extending its applicability are highly desirable. Prior to the work in this thesis, Maneva et al. introduced a Markov Random Field (MRF) formalism for k-SAT problems, on which SP may be viewed as a special case of the well-known belief propagation (BP) algorithm. This result had sometimes been interpreted to an understanding that “SP is BP” and allows a rigorous extension of SP to a “weighted” version, or a family of algorithms, for k-SAT problems. SP has also been generalized, in a non-weighted fashion, for solving non-binary CSPs. Such generalization is however presented using statistical physics language and somewhat difficult to access by more general audience. This thesis generalizes SP both in terms of its applicability to non-binary problems and in terms of introducing “weights” and extending SP to a family of algorithms. Under a generic formulation of CSPs, we first present an understanding of non-weighted SP for arbitrary CSPs in terms of “probabilistic token passing” (PTP). We then show that this probabilistic interpretation of non-weighted SP makes it naturally generalizable to a weighted version, which we call weighted PTP. Another main contribution of this thesis is a disproof of the folk belief that “SP is BP”. We show that the fact that SP is a special case of BP for k-SAT problems is rather incidental. For more general CSPs, SP and generalized SP do not reduce from BP. We also established the conditions under which generalized SP may reduce as special cases of BP. To explore the benefit of generalizing SP to a wide family and for arbitrary, particularly non-binary, problems, we devised a simple weighted PTP based algorithm for solving 3-COL problems. Experimental results, compared against an existing non-weighted SP based algorithm, reveal the potential performance gain that generalized SP may bring.
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Muirhead, Matthew. "Interior wave propagation." Thesis, University of Nottingham, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.289312.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Mikulica, Tomáš. "Light Propagation Volumes." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2015. http://www.nusl.cz/ntk/nusl-234902.

Повний текст джерела
Анотація:
This thesis deals with problem of computation of global illumination in real-time. Two methods are described. Namely Reflective Shadow Maps and Light Propagation Volumes. The first of them deals with the problem by using extended Shadow Mapping algorithm. The second one uses scene embedded into a 3D grid together with Spherical harmonics to compute light propagation in the scene. Furthermore this thesis contains results of measurement of the rendering speed of the Light Propagation Volumes algorithm with various settings on several machines. Quality of the resulting output of the algorithm is also evaluated.
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Růžička, Tomáš. "Light Propagation Volumes." Master's thesis, Vysoké učení technické v Brně. Fakulta informačních technologií, 2016. http://www.nusl.cz/ntk/nusl-255483.

Повний текст джерела
Анотація:
The aim of master thesis is to describe different calculation of global illumination methods including Light Propagation Volumes. All three steps of LPV calculation are widely described: injection, propagation and rendering. It is also proposed several custom extensions improving graphics quality of this method. Two parts of design and implementation are focused on scene description, rendering system, shadow rendering, implementation of LPV method and proposed extensions. As conclusion, measurement and several images of application are presented, followed by comparison in environment with diffenent parameters, thesis summary with evaluation of achieved results and suggestions of further improvements.
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Bertin, Michaël. "Propagation des incertitudes dans un modèle réduit de propagation des infrasons." Thesis, Cachan, Ecole normale supérieure, 2014. http://www.theses.fr/2014DENS0020/document.

Повний текст джерела
Анотація:
La perturbation d’un système peut donner lieu à de la propagation d’onde. Une façon classique d’appréhender ce phénomène est de rechercher les modes propres de vibration du milieu. Mathématiquement, trouver ces modes consiste à rechercher les valeurs et fonctions propres de l’opérateur de propagation. Cependant, d’un point de vue numérique, l’opération peut s’avérer coûteuse car les matrices peuvent avoir de très grandes tailles. En outre, dans la plupart des applications, des incertitudes sont inévitablement associées à notre modèle. La question se pose alors de savoir s’il faut attribuer d’importantes ressources de calcul pour une simulation dont la précision du résultat n’est pas assurée. Nous proposons dans cette thèse une démarche qui permet à la fois de mieux comprendre l’influence des incertitudes sur la propagation et de réduire considérablement les coûts de calcul pour la propagation des infrasons dans l’atmosphère. L’idée principale est que tous les modes n’ont pas la même importance et souvent, seule une poignée d’entre eux suffit à décrire le phénomène sans perte notable de précision. Ces modes s’avèrent être ceux qui sont les plus sensibles aux perturbations atmosphériques. Plus précisément, l’analyse de sensibilité permet d’identifier les structures de l’atmosphère les plus influentes, les groupes de modes qui leur sont associés et les parties du signal infrasonore qui leur correspondent. Ces groupes de modes peuvent être spécifiquement ciblés dans un calcul de spectre au moyen de techniques de projection sur des sous-espace de Krylov, ce qui implique un gain important en coût de calcul. Cette méthode de réduction de modèle peut être appliquée dans un cadre statistique et l’estimation de l’espérance et de la variance du résultat s’effectue là aussi sans perte notable de précision et avec un coût réduit
The perturbation of a system can give rise to wave propagation. A classical approach to understand this phenomenon is to look for natural modes of vibration of the medium. Mathematically, finding these modes requires to seek the eigenvalues and eigenfunctions of the propagation operator. However, from a numerical point of view, the operation can be costly because the matrices can be of very large size. Furthermore, in most applications, uncertainties are inevitably associated with our model. The question then arises as to whether we should allocate significant computational resources for simulation while the accuracy of the result is not guaranteed. We propose in this thesis an approach that allows both a better understanding of the influence of uncertainties on the propagation and a significant decrease of computational costs for infrasound propagation in the atmosphere. The main idea is that all modes do not have the same importance and only a few of them is often sufficient to account for the phenomenon without a significant loss of accuracy. These modes appear to be those which are most sensitive to atmospheric disturbances. Specifically, a sensitivity analysis is used to identify the most influential structures of the atmosphere, the associated groups of modes and their associated parts of the infrasound signal. These groups of modes can be specifically targeted in a spectrum calculation with the projection of the operator onto Krylov subspaces, that allows a significant decrease of the computational cost. This method of model reduction can be applied in a statistical framework as well and estimations of the expectation and the variance of the results are carried out without a significant loss of accuracy and still with a low cost
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Maxwell, Douglas Wayne. "Propagation of Camptotheca acuminata." [College Station, Tex. : Texas A&M University, 2004. http://hdl.handle.net/1969.1/454.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Izquierdo, Fernández Benjamín. "Electromagnetic propagation in tunnels." Doctoral thesis, Universitat Politècnica de Catalunya, 2011. http://hdl.handle.net/10803/38437.

Повний текст джерела
Анотація:
Introduction of wireless communications systems in railway communications are at the origin of this thesis. Ifercat, the company in charge of the development of Línia 9 of Barcelona Metro, decided that wireless systems were employed in order to increase efficiency and safety. For this reason, characterisation of ISM 5.8GHz band in tunnel environments for broad band wireless train communications becomes necessary. Tunnel environments constitute harsh environments due to humidity, obstacles, power systems, moving trains, curves¿ The Automatic Train Control system requires a 20MHz bandwidth for train-to-ground video transmission in order to get on-board information and surveillance. Given that Línia 9 was at the early stages of its development at the beginning of the study, a dual-polarised spectral simulator was developed first. Spectral techniques work in both spatial and spatial-frequency domain and are extremely adaptable to changes in the tunnel cross section as the wave front passes down the tunnel. Efficiency of this technique comes from the well-known properties of FFT algorithms. Spectral techniques provide good near-field predictions and can model different antenna configurations easily. On the other hand, boundary conditions present some issues that must be overcome. Long tunnels also represent a problem in terms of required memory space. The parabolic equation has been used to enhance the performance of spectral techniques far from the source. They complement each other well because parabolic conditions require smooth variations in one direction, thus far from the source, where only field components propagating parallel to the tunnel axis remain, in order to provide accurate results. Application of Leontovich boundary conditions ensures proper solution at the change of media and its low computational cost permits acceleration of predictions. These two techniques are then combined to verify the measurement campaigns developed at metro tunnels during the thesis. MIMO schemes are used to enhance the system throughput and simulation predictions are compared to measurements with good results. The work presented in this thesis consisted first on implementing both simulators and verifying their correct behaviour with theoretical analytical solutions. Secondly, predictions are compared with measurement campaigns carried out in Barcelona Metro environments. The study focuses on EM attenuation, field distribution, fading characterisation, antenna location and MIMO processing at the frequency band of interest.
Стилі APA, Harvard, Vancouver, ISO та ін.
Більше джерел

Книги з теми "Propagation"

1

Bellman, Richard, and Ramabhadra Vasudevan. Wave Propagation. Dordrecht: Springer Netherlands, 1985. http://dx.doi.org/10.1007/978-94-009-5227-0.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Ferrarese, Giorgio, ed. Wave Propagation. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11066-5.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Kim, Yang-Hann. Sound Propagation. Chichester, UK: John Wiley & Sons, Ltd, 2010. http://dx.doi.org/10.1002/9780470825853.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Union, International Telecommunication. Radiowave propagation. Geneva: International Telecommunication Union, 1998.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Royal Horticultural Society (Great Britain), ed. Plant propagation. New York, N.Y: Simon & Schuster published in cooperation with the Royal Horticultural Society, 1988.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

M, Hall M. P., and Barclay L. W, eds. Radiowave propagation. London, United Kingdom: P. Peregrinus on behalf of the Institution of Electrical Engineers, 1989.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Yeung, Edward Chee-Tak, and Yung-I. Lee, eds. Orchid Propagation. New York, NY: Springer US, 2024. http://dx.doi.org/10.1007/978-1-0716-4031-9.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

service), SpringerLink (Online, ed. Wave Propagation. Berlin, Heidelberg: Springer-Verlag Berlin Heidelberg, 2011.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
9

R, Toogood Alan, ed. Plant propagation. New York: DK Pub., 1999.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

M, Dole John, and Gibson James L, eds. Cutting propagation: A guide to propagating and producing floriculture crops. Batavia, Ill: Ball Pub., 2006.

Знайти повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
Більше джерел

Частини книг з теми "Propagation"

1

Solimini, Domenico. "Propagation." In Remote Sensing and Digital Image Processing, 135–63. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-25633-7_5.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Gooch, Jan W. "Propagation." In Encyclopedic Dictionary of Polymers, 592. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_9516.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Simmonds, Andrew. "Propagation." In Data Communications and Transmission Principles, 111–31. London: Macmillan Education UK, 1997. http://dx.doi.org/10.1007/978-1-349-13900-2_5.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Plonsey, Robert, and Roger C. Barr. "Propagation." In Bioelectricity, 105–24. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4757-9456-4_5.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Sharma, Nimisha, Laxuman Sharma, and B. P. Singh. "Propagation." In Strawberries, 179–92. Boca Raton, FL : CRC Press, Taylor & Francis Group, 2019.: CRC Press, 2019. http://dx.doi.org/10.1201/b21441-197.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Mitra, Sisir. "Propagation." In The papaya: botany, production and uses, 37–48. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789241907.0037.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Weik, Martin H. "propagation." In Computer Science and Communications Dictionary, 1355. Boston, MA: Springer US, 2000. http://dx.doi.org/10.1007/1-4020-0613-6_14943.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Mitra, Sisir, and Pravat K. Ray. "Propagation." In Guava: botany, production and uses, 64–88. Wallingford: CABI, 2021. http://dx.doi.org/10.1079/9781789247022.0004.

Повний текст джерела
Анотація:
Abstract This chapter deals with various propagation methods used in the multiplication of guava and progress made so far in this field. Seeds, stem cuttings, root cuttings, air layering, stooling, grafting, budding, rootstock, and in vitro propagation are discussed.
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Ramírez, Fernando, and Thomas Lee Davenport. "Propagation." In Uchuva (Physalis peruviana L.) Reproductive Biology, 105–25. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-66552-4_7.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Vucetic, Branka. "Propagation." In Satellite Communications, 57–101. Boston, MA: Springer US, 1993. http://dx.doi.org/10.1007/978-1-4615-3230-9_2.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.

Тези доповідей конференцій з теми "Propagation"

1

Yu, Fei, and Fengming Liu. "Network rumor propagation model based on the principles of drought propagation." In Seventh International Conference on Advanced Electronic Materials, Computers, and Software Engineering (AEMCSE 2024), edited by Lvqing Yang, 67. SPIE, 2024. http://dx.doi.org/10.1117/12.3038170.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Hawkins, Raymond J. "Numerical path integration: a computationally simple approach to the propagation properties of graded-index dielectric waveguide structures." In OSA Annual Meeting. Washington, D.C.: Optica Publishing Group, 1987. http://dx.doi.org/10.1364/oam.1987.thl6.

Повний текст джерела
Анотація:
I present an improved approach to numerical path integration that expands the scope of the method I discussed recently1 and yields the propagation constants and field distributions of all the modes of a dielectric waveguide structure while retaining the ease of implementation, computational simplicity, and ability to accommodate arbitrarily graded refractive-index profiles characteristic of the previous approach. This approach follows that of Yevick and Hermansson2 in that the propagation properties are obtained by diagonalizing the propagator of the optical wave equation. It differs from their method in the manner by which the propagator is calculated: they use the propagating beam method, I use the Trotter product formula to obtain a closed form expression for the matrix elements of the propagator. The spectral properties calculable using this method are discussed, and the utility of this method in waveguide design is illustrated by calculating the propagation properties of slab waveguide structures.
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Turner, Greg, and Commonwealth Scientific and Industrial Research Org. "Propagation Deconvolution." In Fourth International Conference on Ground Penetrating Radar. European Association of Geoscientists & Engineers, 1992. http://dx.doi.org/10.3997/2214-4609-pdb.303.12.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Monerie, M. "Propagation guidée." In Optoélectronique (Volume 1). Les Ulis, France: EDP Sciences, 1990. http://dx.doi.org/10.1051/sfo/1990014.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

"Wave Propagation." In 10th International Conference on Mathematical Methods in Electromagnetic Theory, 2004. IEEE, 2004. http://dx.doi.org/10.1109/mmet.2004.1397039.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Stoltz, Eric, Michael Wolfe, and Michael P. Gerlek. "Constant propagation." In the 1994 ACM symposium. New York, New York, USA: ACM Press, 1994. http://dx.doi.org/10.1145/326619.326791.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Matalon, Moshe, Changrong Cui, and Thomas Jackson. "Flame Propagation in Channels: Steady and Pulsating Propagation." In 42nd AIAA Aerospace Sciences Meeting and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2004. http://dx.doi.org/10.2514/6.2004-298.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Pereira, Fernando Magno Quintao, and Daniel Berlin. "Wave Propagation and Deep Propagation for Pointer Analysis." In 2009 7th Annual IEEE/ACM International Symposium on Code Generation and Optimization (CGO). IEEE, 2009. http://dx.doi.org/10.1109/cgo.2009.9.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Tian, Xiao-ping, and Ji-hua Lu. "Shortwave Propagation over Oceans and HF Propagation Prediction Model." In 2009 International Conference on Computational Intelligence and Software Engineering. IEEE, 2009. http://dx.doi.org/10.1109/cise.2009.5362511.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Makarov, Denis V., and Aleksandr A. Komissarov. "Modelling of sound propagation in the ocean using the matrix propagator." In 179th Meeting of the Acoustical Society of America. ASA, 2020. http://dx.doi.org/10.1121/2.0001404.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.

Звіти організацій з теми "Propagation"

1

Doss-Hammel, Steve, Douglas Jensen, Charles McGrath, Jeffrey Reid, and Carl Zeisse. Electrooptic Propagation. Fort Belvoir, VA: Defense Technical Information Center, September 2000. http://dx.doi.org/10.21236/ada610160.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
2

Barrios, Amalia E., Kenneth D. Anderson, and Ramakrishna Janaswamy. Electromagnetic Propagation. Fort Belvoir, VA: Defense Technical Information Center, September 2000. http://dx.doi.org/10.21236/ada610168.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
3

Doss-Hammel, Stephen, Charles McGrath, and Jeffrey Reid. Electrooptic Propagation. Fort Belvoir, VA: Defense Technical Information Center, September 2001. http://dx.doi.org/10.21236/ada627904.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
4

Barrios, Amalia E., and Richard Sprague. Propagation Modeling. Fort Belvoir, VA: Defense Technical Information Center, September 2003. http://dx.doi.org/10.21236/ada628911.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
5

Richter, Juergen H. Electromagnetic Propagation. Fort Belvoir, VA: Defense Technical Information Center, September 1997. http://dx.doi.org/10.21236/ada629293.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
6

Barrios, Amalia E., Herbert V. Hitney, Kenneth D. Anderson, and Ramakrishna Janaswamy. Electromagnetic Propagation. Fort Belvoir, VA: Defense Technical Information Center, September 1999. http://dx.doi.org/10.21236/ada629904.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
7

Jensen, Douglas R. Electrooptic Propagation. Fort Belvoir, VA: Defense Technical Information Center, September 1999. http://dx.doi.org/10.21236/ada630092.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
8

Barrios, Amalia E., Kenneth D. Anderson, and Ramakrishna Janaswamy. Electromagnetic Propagation. Fort Belvoir, VA: Defense Technical Information Center, September 2001. http://dx.doi.org/10.21236/ada625828.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
9

Barrios, Amalia E., and Kenneth D. Anderson. Electromagnetic Propagation. Fort Belvoir, VA: Defense Technical Information Center, August 2002. http://dx.doi.org/10.21236/ada627345.

Повний текст джерела
Стилі APA, Harvard, Vancouver, ISO та ін.
10

Malik. L51877 Crack Arrest Toughness to Avoid Dynamic Ductile Fracture in Gas Transmission Pipelines. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), March 2001. http://dx.doi.org/10.55274/r0010192.

Повний текст джерела
Анотація:
Design against long ductile fracture propagation in gas pipelines involves an analysis of the balance between driving force, derived from the gas pressure, and the fracture resistance of the material. Initially, the shelf energy in the Charpy test was successfully used as a measure of fracture propagation resistance. As material strength, pipe diameter and operating pressures increased and required greater fracture propagation resistance, the limitations of the Charpy energy approach became increasingly apparent. This limitation for modern steels is due to the fact that the Charpy test involves significant energy absorption contributions from processes not related to fracture propagation. If an energy-balance approach is to be maintained, and if material resistance is to be measured in a fairly simple laboratory notch bend test (e.g. Charpy or drop-weight tear), the problem reduces to the isolation of the propagation energy absorption per unit of crack advance. To resolve crack propagation energy, a novel modification was evaluated for both Charpy and DWTT specimens by employing a back-slot including a snug fitting shim to replace the removed material. In most cases, this modification was effective in curtailing the load-displacement trace when the propagating crack interacted with the slot on the backside of the specimen. It is also noted that this approach did not affect the initial portion of the load-displacement history and thus allowed crack propagation energies to be resolved.
Стилі APA, Harvard, Vancouver, ISO та ін.
Також вас можуть зацікавити розширені добірки на тему "Propagation" для конкретних типів джерел:
Статті в журналах Дисертації Книги
Ми пропонуємо знижки на всі преміум-плани для авторів, чиї праці увійшли до тематичних добірок літератури. Зв'яжіться з нами, щоб отримати унікальний промокод!

До бібліографії