Artículos de revistas:

1

Schmitz, A., T. Rick, T. Karolski, T. Kuhlen y L. Kobbelt. "Efficient Rasterization for Outdoor Radio Wave Propagation". IEEE Transactions on Visualization and Computer Graphics 17, n.º 2 (febrero de 2011): 159–70. http://dx.doi.org/10.1109/tvcg.2010.96.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

2

Athanaileas, T. E., G. E. Athanasiadou, G. V. Tsoulos y D. I. Kaklamani. "Parallel radio-wave propagation modeling with image-based ray tracing techniques". Parallel Computing 36, n.º 12 (diciembre de 2010): 679–95. http://dx.doi.org/10.1016/j.parco.2010.08.002.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

3

Varela, Mercedes S�nchez y Manuel Garc�a S�nchez. "EGPROM: An empirical-geometrical propagation model to simulate radio wave propagation and diversity reception". Computer Applications in Engineering Education 7, n.º 2 (1999): 120–32. http://dx.doi.org/10.1002/(sici)1099-0542(1999)7:2<120::aid-cae5>3.0.co;2-m.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

4

Adjei-Frimpong, Bernard y László Csurgai-Horváth. "Using Radio Wave Satellite Propagation Measurements for Rain Intensity Estimation". Infocommunications journal, n.º 3 (2018): 2–8. http://dx.doi.org/10.36244/icj.2018.3.1.

Texto completo

Resumen

The European Space Agency launched a communication satellite called Alphasat in 2013, with two experimental beacons to carry out a scientific experiment by measurement at frequencies of 19.7 GHz and 39.4 GHz respectively. Propagation through the atmosphere at these frequencies is affected by the resence of atmospheric gases and other particles like water vapour, rain and ice drops. Rain attenuation is the most significant parameter which degrades the performance of the links by absorbing and scattering radio waves that can be determined as the measured received signal power’s deviation from the nominal, non-attenuated level. Rainfall statistical data are also measured and recorded by the propagation terminals to provide additional information to apply prediction methods that require minutes of integration time rain intensity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

5

Manrique, Luis Carlos, Anthony Weiss y Sandra Puentes. "Simulating Wave Propagation Distribution Through GIS Integration". WSEAS TRANSACTIONS ON INFORMATION SCIENCE AND APPLICATIONS 18 (7 de julio de 2021): 82–90. http://dx.doi.org/10.37394/23209.2021.18.11.

Texto completo

Resumen

The use of electronic devices designed for user location estimation has become widely popular in the last decade. This is thanks to emergent technologies such as Bluetooth Low Energy, Radio-Frequency Identification, and Ultra-WideBand (UWB) among others. In the present study; the authors provide a method for using a Geographic Information System (GIS) to define spatial constraints, in order to simulate the lines of sight of anchors to make an informed selection of adequate locations for installation. By leveraging GIS, researchers or enterprises can improve the installation process by reducing costs while setting up arrangements that will ensure reliable data collection. We include a scenario illustrating the possibility of budget reduction of around 30% related to the orientation and survey of the devices.

Los estilos APA, Harvard, Vancouver, ISO, etc.

6

O'Donoghue, Padraic E., Charles E. Anderson, Gerald J. Friesenhahn y Charles H. Parr. "A Constitutive Formulation for Anisotropic Materials Suitable for Wave Propagation Computer Programs". Journal of Composite Materials 26, n.º 13 (diciembre de 1992): 1860–84. http://dx.doi.org/10.1177/002199839202601301.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

7

Gondarenko, Natalia A., Parvez N. Guzdar, Sidney L. Ossakow y Paul A. Bernhardt. "Perfectly matched layers for radio wave propagation in inhomogeneous magnetized plasmas". Journal of Computational Physics 194, n.º 2 (marzo de 2004): 481–504. http://dx.doi.org/10.1016/j.jcp.2003.09.013.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

8

Aragon-Zavala, A., B. Belloul, V. Nikolopoulos y S. R. Saunders. "Accuracy evaluation analysis for indoor measurement-based radio-wave-propagation predictions". IEE Proceedings - Microwaves, Antennas and Propagation 153, n.º 1 (2006): 67. http://dx.doi.org/10.1049/ip-map:20045131.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

9

Sato, Yoshihito, Ryo Ishiyama y Shigeki Takeda. "Analysis on ceiling space radio wave propagation in indoor environment". Electronics and Communications in Japan 103, n.º 11-12 (6 de octubre de 2020): 31–37. http://dx.doi.org/10.1002/ecj.12272.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

10

Anderson, Ch E., P. A. Cox, G. R. Johnson y P. J. Maudlin. "A constitutive formulation for anisotropic materials suitable for wave propagation computer programs—II". Computational Mechanics 15, n.º 3 (diciembre de 1994): 201–23. http://dx.doi.org/10.1007/bf00375030.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

11

Liu, Wenbin y Dongbing Liu. "Propagation Model of Multi-hop High-frequency Radio in Ocean Signal Attenuation". International Journal of Pattern Recognition and Artificial Intelligence 34, n.º 14 (4 de mayo de 2020): 2058019. http://dx.doi.org/10.1142/s0218001420580197.

Texto completo

Resumen

On the basis of propagation the characteristics of Multi-hop High-Frequency Radio waves in Marine environment, the modeling and analysis method of ocean signal reflection model are firstly introduced from the attenuation of the radio wave. Then the difference between the influence of ocean and earth on wireless communication is studied. By studying the influence of ship on the loss of radio wave propagation, the original ocean model is improved. Finally, an ocean signal reflection model suitable for different marine environments is obtained.

Los estilos APA, Harvard, Vancouver, ISO, etc.

12

Girma, Solomon T., Dominic B. O. Konditi y Ciira Maina. "A Novel Radio Wave Propagation Modeling Method Using System Identification Technique over Wireless Links in East Africa". International Journal of Antennas and Propagation 2018 (26 de noviembre de 2018): 1–7. http://dx.doi.org/10.1155/2018/2162570.

Texto completo

Resumen

Transmission of a radio signal through a wireless radio channel is affected by refraction, diffraction and reflection, free space loss, object penetration, and absorption that corrupt the originally transmitted signal before radio wave arrives at a receiver antenna. Even though there are many factors affecting wireless radio channels, there are still a number of radio wave propagation models such as Okumura, Hata, free space model, and COST-231 to predict the received signal level at the receiver antenna. However, researchers in the field of radio wave propagation argue that there is no universally accepted propagation model to guarantee a universal recommendation. Thus, this research is aimed at determining the difference between the measured received signal levels and the received signal level calculated from the free space propagation model. System identification method has been proposed to determine this unknown difference. Measured received signal levels were collected from three randomly selected urban areas in Ethiopia using a computer, Nemo test tool, Actix software, Nokia phone, and GPS. The result from the simulations was validated against the received experimental signal level measurement taken in a different environment. From the simulation results, the mean square error (MSE) was 4.169 dB, which is much smaller than the minimum acceptable MSE value of 6 dB for good signal propagation, and 74.76% fit to the estimation data. The results clearly showed that the proposed radio wave propagation model predicts the received signal levels at 900 MHz and 1800 MHz in the study region.

Los estilos APA, Harvard, Vancouver, ISO, etc.

13

HARA, Masaki, Hitoshi SHIMASAKI, Yuichi KADO y Masatoshi ICHIDA. "Effect of Vegetation Growth on Radio Wave Propagation in 920-MHz Band". IEICE Transactions on Communications E99.B, n.º 1 (2016): 81–86. http://dx.doi.org/10.1587/transcom.2015isp0021.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

14

Yu Song Meng, Yee Hui Lee y Boon Chong Ng. "The Effects of Tropical Weather on Radio-Wave Propagation Over Foliage Channel". IEEE Transactions on Vehicular Technology 58, n.º 8 (octubre de 2009): 4023–30. http://dx.doi.org/10.1109/tvt.2009.2021480.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

15

Chen, Zhongqiang, Alex Delis y Henry L. Bertoni. "Radio-wave propagation prediction using ray-tracing techniques on a network of workstations (NOW)". Journal of Parallel and Distributed Computing 64, n.º 10 (octubre de 2004): 1127–56. http://dx.doi.org/10.1016/j.jpdc.2004.07.004.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

16

Ferrer-Coll, J., P. Stenumgaard, P. Ängskog y J. Chilo. "Characterisation of highly absorbent and highly reflective radio wave propagation environments in industrial applications". IET Communications 6, n.º 15 (16 de octubre de 2012): 2404–12. http://dx.doi.org/10.1049/iet-com.2012.0028.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

17

Jun Horikoshi, K. Tanaka y T. Morinaga. "1.2 GHz band wave propagation measurements in concrete building for indoor radio communications". IEEE Transactions on Vehicular Technology 35, n.º 4 (noviembre de 1986): 146–52. http://dx.doi.org/10.1109/t-vt.1986.24084.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

18

Weiner, M. "Use of the Longley-Rice and Johnson-Gierhart Tropospheric Radio Propagation Programs:0.02-20 GHz". IEEE Journal on Selected Areas in Communications 4, n.º 2 (marzo de 1986): 297–307. http://dx.doi.org/10.1109/jsac.1986.1146313.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

19

Suryawanshi, Prakash, Sanjay Dambhare y Ashutosh Pramanik. "Detection of Electromechanical Wave Propagation Using Synchronized Phasor Measurements". International Journal of Emerging Electric Power Systems 15, n.º 1 (14 de enero de 2014): 69–75. http://dx.doi.org/10.1515/ijeeps-2013-0155.

Texto completo

Resumen

Abstract Considering electrical network as a continuum has become popular for electromechanical wave analysis. This paper reviews the concept of electromechanical wave propagation. Analysis of large number of generator ring system will be an easy way to illustrate wave propagation. The property of traveling waves is that the maximum and minimum values do not occur at the same time instants and hence the difference between these time delays can be easily calculated. The homogeneous, isotropic 10 generator ring system is modeled using electromagnetic transient simulation programs. The purpose of this study is to investigate the time delays and wave velocities using Power System Computer Aided Design (PSCAD)/Electromagnetic Transient Program (EMTP). The disturbances considered here are generator disconnections and line trips.

Los estilos APA, Harvard, Vancouver, ISO, etc.

20

Yang, M. y S. Stavrou. "Three-dimensional modal transmission-line method for radio wave propagation through periodic building structures". IEE Proceedings - Microwaves, Antennas and Propagation 152, n.º 6 (2005): 597. http://dx.doi.org/10.1049/ip-map:20045097.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

21

Wang, Haiming, Peize Zhang, Jing Li y Xiaohu You. "Radio propagation and wireless coverage of LSAA-based 5G millimeter-wave mobile communication systems". China Communications 16, n.º 5 (mayo de 2019): 1–18. http://dx.doi.org/10.23919/j.cc.2019.05.001.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

22

Isabona, Joseph y Divine O. Ojuh. "Application of Levenberg-Marguardt Algorithm for Prime Radio Propagation Wave Attenuation Modelling in Typical Urban, Suburban and Rural Terrains". International Journal of Intelligent Systems and Applications 13, n.º 3 (8 de junio de 2021): 35–42. http://dx.doi.org/10.5815/ijisa.2021.03.04.

Texto completo

Resumen

The desire to achieve an adaptive prognostics regression learning processes of physical and empirical phenomenon is a complex task and open problem in radio frequency telecommunication engineering. One key method to solving such complex task or problems is by means of numerical based optimisation algorithms. The Levenberg–Marquardt algorithm (LMA) is an efficient nonlinear parametric machine learning based modelling algorithm with optimal, fast, and accurate convergence speed. This paper proposes and demonstrates the real-time application of the LMA in developing a log-distance like propagation loss model based on received radio strength measurements conducted over deployed long term evolution (LTE) eNodeBs antennas in three different propagation areas. The LTE eNodeB signal propagation areas were selected to reflect typical urban, suburban and rural terrains which represent urban, suburban and rural terrains. The heights of the three eNodeBs are 30, 28 and 32m respectively and each operate at 2.6GHz carrier frequency with 10MHz channel bandwidths. The resultant outcome of the proposed propagation loss modelling using LMA indicates a high approximation efficacy over the popular Gauss-Newton algorithm (GNA) modelling method, which has been used to benchmark the process. Precisely, the developed propagation loss model using LMA method attained lower maximum absolute error (MABE) of 7.73, 14.57and 10.53 for urban, suburban and rural terrains compared to the ones developed by GNA which yielded 15.19, 16.59 and 13.05 MABE values. The improved approximation performance of the LMA over the GNA can be ascribed to its capacity handle multiple free parameters and attain optimum solution irrespective of the selected values of initial guess parameters.

Los estilos APA, Harvard, Vancouver, ISO, etc.

23

Solomitckii, Dmitrii, Yevgeni Koucheryavy, Vasilii Semkin, Aki Karttunen, Vitaly Petrov, Sinh Le Hong Nguyen, Hosein Nikopour, Katsuyuki Haneda, Sergey Andreev y Shilpa Talwar. "Characterizing Radio Wave Propagation in Urban Street Canyon With Vehicular Blockage at 28 GHz". IEEE Transactions on Vehicular Technology 69, n.º 2 (febrero de 2020): 1227–36. http://dx.doi.org/10.1109/tvt.2019.2959127.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

24

Davies, O. T. y P. A. Watson. "GPS phase-delay measurement: Technique for the calibration and analysis in millimetre-wave radio propagation studies". IEE Proceedings - Microwaves, Antennas and Propagation 146, n.º 6 (1999): 369. http://dx.doi.org/10.1049/ip-map:19990780.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

25

Buzin, Vladimir, Dmitry Edemsky, Sergey Gudoshnikov, Vladimir Kopeikin, Pavel Morozov, Alexey Popov, Igor Prokopovich et al. "Search for Chelyabinsk Meteorite Fragments in Chebarkul Lake Bottom (GPR and Magnetic Data)". Journal of Telecommunications and Information Technology, n.º 3 (2017): 69–78. http://dx.doi.org/10.26636/jtit.2017.120817.

Texto completo

Resumen

The paper summarizes experimental efforts of the Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN) undertaken in search of the biggest part of Chelyabinsk meteorite in the bottom of lake Chebarkul, South Ural, Russia, and to estimate the ecological effects of its subsequent excavation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

26

Vafidis, A., F. Abramovici y E. R. Kanasewich. "Elastic wave propagation using fully vectorized high order finite‐difference algorithms". GEOPHYSICS 57, n.º 2 (febrero de 1992): 218–32. http://dx.doi.org/10.1190/1.1443235.

Texto completo

Resumen

Two finite‐difference schemes for solving the elastic wave equation in heterogeneous two‐dimensional media are implemented on a vector computer. A modified Lax‐Wendroff scheme that is second‐order accurate both in time and space and is a version of the MacCormack scheme that is second‐order accurate in time and fourth‐order in space. The algorithms are based on the matrix times vector by diagonals technique that is fully vectorized and is described using a novel notation for vector supercomputer operations. The technique described can be implemented on a vector processor of modest dimensions and increase the applicability of finite differences. The two difference operators are compared and the programs are tested for a simple case of standing sinusoidal waves for which the exact solution is known and also for a two‐layer model with a line source. A comparison of the results for an actual well‐to‐well experiment verifies the usefulness of the two‐dimensional approach in modeling the results.

Los estilos APA, Harvard, Vancouver, ISO, etc.

27

Lv, Zhengnan y Zhenghao Xi. "Radio Frequency Link and User Selection Algorithm for 5G Mobile Communication System". Complexity 2021 (18 de mayo de 2021): 1–10. http://dx.doi.org/10.1155/2021/1976499.

Texto completo

Resumen

Based on the millimetre-wave time-domain channel detector, this paper conducts channel measurement and modelling for different scenarios and antenna types in typical frequency bands and thus carries out a study on the propagation characteristics of millimetre-wave channels in typical frequency bands and scenarios for 5G. The time-varying characteristics and modelling methods of millimetre-wave clusters are studied, and the time-varying channel simulation strategy and linear regression fitting method are used to establish the time-varying generation and extinction model of clusters by combining the measured data of 26 GHz large-scale antenna channels. The algorithm is based on the correlation dictionary and achieves the efficient and optimal selection of large-scale antenna arrays in the millimetre-wave band. A low-complexity multiuser hybrid precoding design scheme is proposed based on the wideband millimetre-wave large-scale Multiple-Input Multiple-Output (MIMO) system. The scheme aims to maximize the system spectral efficiency and introduces the net spectral efficiency as a bridge to decouple the analogy precoding design from the digital precoding design, thus significantly reducing the computational complexity. In the analogy precoding stage, a Hungarian algorithm-based beam assignment method is proposed to avoid beam conflicts and maximize the net spectral efficiency of the system; in the digital precoding stage, the equivalent channel matrix of each subcarrier is diagonalized to eliminate multiuser interference. Finally, the effectiveness of the scheme is verified by simulation. In this paper, we focus on the radio frequency (RF) link and user selection algorithm of 5G mobile communication system. Through the study of these two aspects, the RF link of our communication system has high stability and reliability, and through the study of the algorithm used for selection, our results also have a strong practical value.

Los estilos APA, Harvard, Vancouver, ISO, etc.

28

Corre, Y. y Y. Lostanlen. "Three-Dimensional Urban EM Wave Propagation Model for Radio Network Planning and Optimization Over Large Areas". IEEE Transactions on Vehicular Technology 58, n.º 7 (septiembre de 2009): 3112–23. http://dx.doi.org/10.1109/tvt.2009.2016973.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

29

Zhang, Peize, Haiming Wang y Wei Hong. "Radio propagation measurement and cluster-based analysis for millimeter-wave cellular systems in dense urban environments". Frontiers of Information Technology & Electronic Engineering 22, n.º 4 (abril de 2021): 471–87. http://dx.doi.org/10.1631/fitee.2000489.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

30

Myagmardulam, Bilguunmaa, Ryu Miura, Fumie Ono, Toshinori Kagawa, Lin Shan, Tadachika Nakayama, Fumihide Kojima y Baasandash Choijil. "Performance Evaluation of LoRa 920 MHz Frequency Band in a Hilly Forested Area". Electronics 10, n.º 4 (20 de febrero de 2021): 502. http://dx.doi.org/10.3390/electronics10040502.

Texto completo

Resumen

Long-range (LoRa) wireless communication technology has been widely used in many Internet-of-Things (IoT) applications in industry and academia. Radio wave propagation characteristics in forested areas are important to ensure communication quality in forest IoT applications. In this study, 920 MHz band propagation characteristics in forested areas and tree canopy openness were investigated in the Takakuma experimental forest in Kagoshima, Japan. The aim was to evaluate the performance of the LoRa 920 MHz band with spreading factor (SF12) in a forested hilly area. The received signal strength indicator (RSSI) was measured as a function of the distance between the transmitter antenna and ground station (GS). To illustrate the effect of canopy openness on radio wave propagation, sky view factor (SVF) and a forest canopy height model were considered at each location of a successfully received RSSI. A positive correlation was found between the RSSI and SVF. It was found that between the GS and transmitter antenna, if the canopy height is above 23 m, the signal diffracted and RSSI fell to −120 to −127 dBm, so the presence of the obstacle height should be considered. Further research is needed to clarify the detailed tree density between the transmitter and ground station to propose an optimal propagation model for a forested environment.

Los estilos APA, Harvard, Vancouver, ISO, etc.

31

Lin, Xuemei y Jiande Z. Chen. "Abnormal gastric slow waves in patients with functional dyspepsia assessed by multichannel electrogastrography". American Journal of Physiology-Gastrointestinal and Liver Physiology 280, n.º 6 (1 de junio de 2001): G1370—G1375. http://dx.doi.org/10.1152/ajpgi.2001.280.6.g1370.

Texto completo

Resumen

The aim of this study was to utilize multichannel electrogastrography to investigate whether patients with functional dyspepsia had impaired propagation or coordination of gastric slow waves in the fasting state compared with healthy controls. The study was performed in 10 patients with functional dyspepsia and 11 healthy subjects. Gastric myoelectrical activity was measured by using surface electrogastrography with a specially designed four-channel device. The study was performed for 30 min or more in the fasting state. Special computer programs were developed for the computation of the propagation and coupling of the gastric slow wave. It was found that, compared with the healthy controls, the patients showed a significantly lower percentage of slow wave propagation (58.0 ± 8.9 vs. 89.9 ± 2.6%, P < 0.002) and a significantly lower percentage of slow wave coupling (46.9 ± 4.4 vs. 61.5 ± 6.9%, P < 0.04). In addition, the patients showed inconsistencies in the frequency and regularity of the gastric slow wave among the four-channel electrogastrograms (EGGs). It was concluded that patients with functional dyspepsia have impaired slow wave propagation and coupling. Multichannel EGG has more information than single-channel EGG for the detection of gastric myoelectrical abnormalities.

Los estilos APA, Harvard, Vancouver, ISO, etc.

32

Oraizi, Homayoon y Shahram Hosseinzadeh. "Radio-Wave-Propagation Modeling in the Presence of Multiple Knife Edges by the Bidirectional Parabolic-Equation Method". IEEE Transactions on Vehicular Technology 56, n.º 3 (mayo de 2007): 1033–40. http://dx.doi.org/10.1109/tvt.2007.895496.

Texto completo

Los estilos APA, Harvard, Vancouver, ISO, etc.

33

González-Plaza, Ana, César Calvo-Ramírez, César Briso-Rodríguez, Juan Moreno García-Loygorri, David Oliva y José I. Alonso. "Propagation at mmW Band in Metropolitan Railway Tunnels". Wireless Communications and Mobile Computing 2018 (2018): 1–10. http://dx.doi.org/10.1155/2018/7350494.

Texto completo

Resumen

The next generation of mobile communications, 5G, will provide a wideband network based on microwave and millimeter-wave (mmW) communication radio links with the goal of fulfilling the strict and severe requirements of the future test cases. In particular, this paper research is focused on mmW bands in metropolitan railway tunnels. For that purpose, a propagation measurement campaign was performed at 24 GHz band in a passenger train on a realist subway environment, and these results were combined with simulations ad hoc for tunnels and a theoretical modal propagation model. A narrowband and a wideband study have been conducted with the aim of obtaining the path loss, fading, power-delay profile, and angle of arrival, taking into consideration horizontal and vertical polarization in the receiving and transmitting antennas. This validation can be used to design and deploy wideband mobile communication networks at mmW bands in railway scenarios.

Los estilos APA, Harvard, Vancouver, ISO, etc.

34

Banaseka, Frank Kataka, Ferdinand Katsriku, Jamal Deen Abdulai, Kofi Sarpong Adu-Manu y Felicia Nana Ama Engmann. "Signal Propagation Models in Soil Medium for the Study of Wireless Underground Sensor Networks: A Review of Current Trends". Wireless Communications and Mobile Computing 2021 (2 de abril de 2021): 1–12. http://dx.doi.org/10.1155/2021/8836426.

Texto completo

Resumen

Radio signal propagation modeling plays an important role in the design of wireless communication systems. Various models have been developed, over the past few decades, to predict signal propagation and behavior for wireless communication systems in different operating environments. Recently, there has been an interest in the deployment of wireless sensors in soil. To fully exploit the capabilities of sensor networks deployed in soil requires an understanding of the propagation characteristics within this environment. This paper reviews the cutting-edge developments of signal propagation in the subterranean environment. The most important modeling techniques for modeling include electromagnetic waves, propagation loss, magnetic induction, and acoustic wave. These are discussed vis-a-vis modeling complexity and key parameters of the environment including electric and magnetic properties of soil. An equation to model propagation in the soil is derived from the free space model. Results are presented to show propagation losses and at different frequencies and volumetric water content. The channel capacity and the operating frequency are also analyzed against soil moisture at different soil types and antenna sizes.

Los estilos APA, Harvard, Vancouver, ISO, etc.

35

Gui, Jinsong y Fujian Cai. "Efficient Radio Channel Allocation in Integrated mmWave/Sub-6 GHz UAV-Assisted Disaster Relief Networks". Mobile Information Systems 2021 (21 de agosto de 2021): 1–18. http://dx.doi.org/10.1155/2021/6707804.

Texto completo

Resumen

The unmanned aerial vehicle- (UAV-) assisted sub-6 GHz disaster relief networks cannot meet high-speed transmission requirements. In this paper, the millimeter wave (mmWave) frequency band is combined with the sub-6 GHz frequency band to build a high-speed UAV-assisted disaster relief network. However, the high propagation path loss of mmWave signals usually needs to be compensated by beamforming, where the ground-facing beam of each UAV is the desired receiving beam of ground user information. The different channels need to be allocated to a single UAV so that this kind of beam can be used simultaneously by different ground users to communicate with this UAV. Also, the other UAVs should reuse these channels as much as possible to save spectrum resources. In this paper, the beamforming training (BFT) mechanism is firstly used to obtain the signal-to-noise ratio (SNR) values of all possible links between ground terminals and UAVs, which are used to estimate these links’ energy efficiency. Then, an interference graph construction algorithm is proposed to identify the links that cannot be used simultaneously in the same channel according to the system energy efficiency. Finally, an iterative channel allocation algorithm is designed to allocate new channels to eliminate the edges of the interference graph, so that the links obtained by the BFT process can be used simultaneously as much as possible under the constraint of the number of channels. The simulation results show that our proposed scheme can achieve the shorter average convergence time, the higher data rate (or the lower data loss rate), and the higher energy efficiency.

Los estilos APA, Harvard, Vancouver, ISO, etc.

36

Al-samman, Ahmed M., Tharek Abd Rahman y Marwan Hadri Azmi. "Indoor Corridor Wideband Radio Propagation Measurements and Channel Models for 5G Millimeter Wave Wireless Communications at 19 GHz, 28 GHz, and 38 GHz Bands". Wireless Communications and Mobile Computing 2018 (2018): 1–12. http://dx.doi.org/10.1155/2018/6369517.

Texto completo

Resumen

This paper presents millimeter wave (mmWave) measurements in an indoor environment. The high demands for the future applications in the 5G system require more capacity. In the microwave band below 6 GHz, most of the available bands are occupied; hence, the microwave band above 6 GHz and mmWave band can be used for the 5G system to cover the bandwidth required for all 5G applications. In this paper, the propagation characteristics at three different bands above 6 GHz (19, 28, and 38 GHz) are investigated in an indoor corridor environment for line of sight (LOS) and non-LOS (NLOS) scenarios. Five different path loss models are studied for this environment, namely, close-in (CI) free space path loss, floating-intercept (FI), frequency attenuation (FA) path loss, alpha-beta-gamma (ABG), and close-in free space reference distance with frequency weighting (CIF) models. Important statistical properties, such as power delay profile (PDP), root mean square (RMS) delay spread, and azimuth angle spread, are obtained and compared for different bands. The results for the path loss model found that the path loss exponent (PLE) and line slope values for all models are less than the free space path loss exponent of 2. The RMS delay spread for all bands is low for the LOS scenario, and only the directed path is contributed in some spatial locations. For the NLOS scenario, the angle of arrival (AOA) is extensively investigated, and the results indicated that the channel propagation for 5G using high directional antenna should be used in the beamforming technique to receive the signal and collect all multipath components from different angles in a particular mobile location.

Los estilos APA, Harvard, Vancouver, ISO, etc.

37

Kalistatov, Kalistratov Dmitry. "Wireless Video Monitoring of the Megacities Transport Infrastructure". Civil Engineering Journal 5, n.º 5 (22 de mayo de 2019): 1033–40. http://dx.doi.org/10.28991/cej-2019-03091309.

Texto completo

Resumen

The article discusses the development of megacities transport infrastructure. The problem of traffic congestion is touched upon, the task of optimal road design is justified. In the context of these issues gives a system of wireless video monitoring of traffic flows on base of digital panoramic video images. The main objective is to obtain a universal mathematical model for the description of a radio signal with any type of digital modulation. This will greatly facilitate the parametric calculation of the radio channel for image transmission and the design of the monitoring system. The objective is achieved by applying the Fourier method of separation of variables in combination with computer simulation methods. As result, a highly accurate universal mathematical model of radio signal with digital modulation is proposed. The scientific novelty of the model is that it allows to simulate the propagation of a radio signal with an arbitrary waveform. Thanks to this, the model covers almost all common types of digital modulation of the radio signal. In addition, the model takes into account the internal noise of the equipment and the external interference of the radio channel. The article describes in detail the process of solving the wave equation, underlying the model. Examples of modeling are given, the advantages and disadvantages of the model are indicated. Recommendations are made on its use for calculating radio channels and designing systems for analyzing and developing the transport infrastructure of a megacity.

Los estilos APA, Harvard, Vancouver, ISO, etc.

38

Giacomin, João C., Flávio H. Vasconcelos y Elson J. Silva. "A distributed measurement system to estimate plant water content in agricultural fields based on wireless sensor networks". Sba: Controle & Automação Sociedade Brasileira de Automatica 19, n.º 4 (diciembre de 2008): 367–78. http://dx.doi.org/10.1590/s0103-17592008000400001.

Texto completo

Resumen

This paper proposes a distributed measuring system based on wireless sensor networks (WSN) employed to estimate vegetation water content in agricultural fields. A WSN deployed along the whole field permits to measure and map soil, air and plant variables and transmit these data, by small radios, to a central computer. Water content is obtained by measuring the attenuation of the network communication signals (RF), without the use of any specific sensor. The need of distributed measurements to estimate agricultural crop parameters is pointed out. A mathematical model of radio wave propagation through vegetation is used to develop the method of estimating vegetation water content with a RSSF. Field tests confirmed the viability of the proposal.

Los estilos APA, Harvard, Vancouver, ISO, etc.

39

Kiciński, Radosław y Bogdan Szturomski. "Pressure Wave Caused by Trinitrotoluene (TNT) Underwater Explosion—Short Review". Applied Sciences 10, n.º 10 (15 de mayo de 2020): 3433. http://dx.doi.org/10.3390/app10103433.

Texto completo

Resumen

The development of computational techniques and computer hardware has an impact the analysis of short-term (fast-changing) processes, such as the impact of a non-contact underwater explosion pressure waves. A theory of underwater explosions, gas bubble formation and pressure waves are presented. The course of the pressure wave in time, and its propagation in the acoustic medium are presented. The study presents empirical descriptions of non-contact pressure explosion waves. We propose to use them in simulations of ship hull strength and other objects immersed in liquids that are exposed to the effects of non-contact trinitrotoluene (TNT)-charge explosions. Pressure distributions and their time courses given by authors such as R.H. Cole, J.S. Nawagin, W. Stiepanow, T.E. Farley and H.G. Snay, T.L. Geers and K.S. Hunter are compared. A method of pressure wave modeling using acoustic media implemented in Computer Aided Engineering (CAE) programs is presented. The results of the values and the time course of the pressure acting on the underwater object are given. The influence of FEM (Finite Element Method) mesh density on the obtained results is examined and presented. The aim of the article is to expand our knowledge of underwater explosions, compare mathematical descriptions of the pressure waves developed by different authors and show the differences between them. In addition, we present the distinction between contact and non-contact explosions and analyze how changes in the mesh density of acoustic elements affects the reflection of the incident wave caused by an underwater explosion.

Los estilos APA, Harvard, Vancouver, ISO, etc.

40

Keam, R. B., J. R. Holdem y J. A. Schoonees. "Soil moisture profile estimation from surface measurements at multiple frequencies". Soil Research 37, n.º 6 (1999): 1107. http://dx.doi.org/10.1071/sr99011.

Texto completo

Resumen

It is possible to obtain estimates in situ of volumetric soil moisture content (SMC) as a function of depth using measurements of radio wave reflection at the soil surface at several discrete frequencies. The feasibility of the method was demonstrated through computer simulation by deriving empirical relationships between the number of frequencies, the frequency range, and the number of soil layers for which the SMC is estimated. The SMC profile was obtained to a depth of 1.5 m by inverting, through function minimisation, a simulation of the reflection coefficient from layered dielectric materials. The number of soil layers in which SMC could be resolved was found to be twice the number of frequencies used. The required bandwidth increased with the number of soil layers from 20 MHz for 6 layers to 140 MHz for 16 layers. Within some assumptions about the nature of the radio wave propagation, the theoretical accuracy of the estimate depended only on the quantisation error introduced by having to consider discrete layers of uniform soil with finite thicknesses. The method may have potential for enabling sensitive measurements of SMC profiles at lower cost and lower complexity than methods which use analysis of steps or pulses, such as time-domain reflectometry, and should be well suited for routine use by horticulturists and soil researchers.

Los estilos APA, Harvard, Vancouver, ISO, etc.

41

Lee, Seung-Yop y C. D. Mote. "Vibration Control of an Axially Moving String by Boundary Control". Journal of Dynamic Systems, Measurement, and Control 118, n.º 1 (1 de marzo de 1996): 66–74. http://dx.doi.org/10.1115/1.2801153.

Texto completo

Resumen

The stabilization of the transverse vibration of an axially moving string is implemented using time-varying control of either the boundary transverse motion or the external boundary forces. The total mechanical energy of the translating string is a Lyapunaov functional and boundary control laws are designed to dissipate the total vibration energy of the string at the left and/or right boundary. An optimal feedback gain determined by minimizing the energy reflected from the boundaries, is the radio of tension to the propagation velocity of an incident wave to the boundary control. Also the maximum time required to stabilize all vibration energy of the system for any initial disturbance is the time required for a wave to propagate the span of the string before hitting boundary control. Asymptotic and exponential stability of the axially moving string under boundary control are verified analytically through the decay rate of the energy norm and the use of semigroup theory. Simulations are used to verify the theoretically predicted, optimal boundary control for the stabilization of the translating string.

Los estilos APA, Harvard, Vancouver, ISO, etc.

42

Smadi, Mahmoud M. y Mahmoud H. Alrefaei. "New extensions of Rayleigh distribution based on inverted-Weibull and Weibull distributions". International Journal of Electrical and Computer Engineering (IJECE) 11, n.º 6 (1 de diciembre de 2021): 5107. http://dx.doi.org/10.11591/ijece.v11i6.pp5107-5118.

Texto completo

Resumen

The Rayleigh distribution was proposed in the fields of acoustics and optics by lord Rayleigh. It has wide applications in communication theory, such as description of instantaneous peak power of received radio signals, i.e. study of vibrations and waves. It has also been used for modeling of wave propagation, radiation, synthetic aperture radar images, and lifetime data in engineering and clinical studies. This work proposes two new extensions of the Rayleigh distribution, namely the Rayleigh inverted-Weibull (RIW) and the Rayleigh Weibull (RW) distributions. Several fundamental properties are derived in this study, these include reliability and hazard functions, moments, quantile function, random number generation, skewness, and kurtosis. The maximum likelihood estimators for the model parameters of the two proposed models are also derived along with the asymptotic confidence intervals. Two real data sets in communication systems and clinical trials are analyzed to illustrate the concept of the proposed extensions. The results demonstrated that the proposed extensions showed better fitting than other extensions and competing models.

Los estilos APA, Harvard, Vancouver, ISO, etc.

43

Yin, Liang, Ruonan Yang y Yuliang Yao. "Channel Sounding and Scene Classification of Indoor 6G Millimeter Wave Channel Based on Machine Learning". Electronics 10, n.º 7 (1 de abril de 2021): 843. http://dx.doi.org/10.3390/electronics10070843.

Texto completo

Resumen

Millimeter wave, especially the high frequency millimeter wave near 100 GHz, is one of the key spectrum resources for the sixth generation (6G) mobile communication, which can be used for precise positioning, imaging and large capacity data transmission. Therefore, high frequency millimeter wave channel sounding is the first step to better understand 6G signal propagation. Because indoor wireless deployment is critical to 6G and different scenes classification can make future radio network optimization easy, we built a 6G indoor millimeter wave channel sounding system using just commercial instruments based on time-domain correlation method. Taking transmission and reception of a typical 93 GHz millimeter wave signal in the W-band as an example, four indoor millimeter wave communication scenes were modeled. Furthermore, we proposed a data-driven supervised machine learning method to extract fingerprint features from different scenes. Then we trained the scene classification model based on these features. Baseband data from receiver was transformed to channel Power Delay Profile (PDP), and then six fingerprint features were extracted for each scene. The decision tree, Support Vector Machine (SVM) and the optimal bagging channel scene classification algorithms were used to train machine learning model, with test accuracies of 94.3%, 86.4% and 96.5% respectively. The results show that the channel fingerprint classification model trained by machine learning method is effective. This method can be used in 6G channel sounding and scene classification to THz in the future.

Los estilos APA, Harvard, Vancouver, ISO, etc.

44

Thomsen, Leon. "Converted‐wave reflection seismology over inhomogeneous, anisotropic media". GEOPHYSICS 64, n.º 3 (mayo de 1999): 678–90. http://dx.doi.org/10.1190/1.1444577.

Texto completo

Resumen

Converted‐wave processing is more critically dependent on physical assumptions concerning rock velocities than is pure‐mode processing, because not only moveout but also the offset of the imaged point itself depend upon the physical parameters of the medium. Hence, unrealistic assumptions of homogeneity and isotropy are more critical than for pure‐mode propagation, where the image‐point offset is determined geometrically rather than physically. In layered anisotropic media, an effective velocity ratio [Formula: see text] (where [Formula: see text] is the ratio of average vertical velocities and γ2 is the corresponding ratio of short‐spread moveout velocities) governs most of the behavior of the conversion‐point offset. These ratios can be constructed from P-wave and converted‐wave data if an approximate correlation is established between corresponding reflection events. Acquisition designs based naively on γ0 instead of [Formula: see text] can result in suboptimal data collection. Computer programs that implement algorithms for isotropic homogeneous media can be forced to treat layered anisotropic media, sometimes with good precision, with the simple provision of [Formula: see text] as input for a velocity ratio function. However, simple closed‐form expressions permit hyperbolic and posthyperbolic moveout removal and computation of conversion‐point offset without these restrictive assumptions. In these equations, vertical traveltime is preferred (over depth) as an independent variable, since the determination of the depth is imprecise in the presence of polar anisotropy and may be postponed until later in the flow. If the subsurface has lateral variability and/or azimuthal anisotropy, then the converted‐wave data are not invariant under the exchange of source and receiver positions; hence, a split‐spread gather may have asymmetric moveout. Particularly in 3-D surveys, ignoring this diodic feature of the converted‐wave velocity field may lead to imaging errors.

Los estilos APA, Harvard, Vancouver, ISO, etc.

45

Tikhvinskiy, Valery, Grigory Bochechka, Pavel Korchagin, Shakhmaran Seilov y Andrey Gryazev. "Sharing Spectrum UE LTE and Air-Traffic Control Radars in 800 MHz Band". Journal of Telecommunications and Information Technology, n.º 2 (30 de junio de 2017): 49–53. http://dx.doi.org/10.26636/jtit.2017.114317.

Texto completo

Resumen

The need to ensure LTE network coverage in sparsely populated and rural areas of Europe (ITU Region 1) has led to a massive use of 800 MHz band (band 20) with its good characteristics of radio wave propagation in LTE networks. However, the frequency band of 800 MHz called “digital dividend” in Region 1 is used on a primary basis not only by the terrestrial mobile service but also by air-traffic control radars (ATCR) that can lead to the creation of harmful interferences at the receivers’ input of ATCR. Such scenarios of mutual interferences became possible after granting licenses for LTE-800 frequencies to operators in such countries as Azerbaijan, Kazakhstan, Russia and other CIS countries, so this problem should be solved by operators at the deployment of LTE-800 networks in airports and areas close to them. So far, for such scenarios the ITU and CEPT have not formulated criteria for interference protection. The proposed protection criteria for receivers of ATCR from user devices’ interferences of LTE-800 networks were tested by experimental studies and can provide a solution to the electromagnetic compatibility (EMC) problem in a complex electromagnetic environment of modern airports and cross-order coordination of 800 MHz frequency bands in Region 1.

Los estilos APA, Harvard, Vancouver, ISO, etc.

46

Timofeev, A. L. y A. Kh Sultanov. "Building a noise-tolerant code based on a holographic representation of arbi-trary digital information". Computer Optics 44, n.º 6 (diciembre de 2020): 978–84. http://dx.doi.org/10.18287/2412-6179-co-739.

Texto completo

Resumen

The article considers a method of error-correcting coding based on the holographic representation of a digital signal. The message encoding process is a mathematical simulation of a hologram created in virtual space by a wave from an input signal source. The code word is a hologram of a point, it is also a one-dimensional zone ruler that carries information about the input data block in the form of an n-bit code of the coordinate of the center of the Fresnel zones. It is shown that the holographic representation of the signal has significantly greater noise immunity and allows you to restore the original digital combination when most of the code message is lost and when the encoded signal is distorted by noise several times higher than the signal level. To assess the noise immunity, the reliability of information transmission over the channel with additive white Gaussian noise is compared using the Reed-Solomon code, the Reed-Muller code, the majority code, and the holographic code. The comparative efficiency of codes in the presence of packet errors caused by the effect of fading due to multipath propagation in radio channels is considered. It is shown that holographic coding provides the correction of packet errors regardless of the length of the packet and its location in the codeword. The holographic code is of interest for transmitting information over channels with a low signal-to-noise ratio (space communications and optical communication systems using free space as a transmission channel, terrestrial, including mobile radio communications), as well as for storing information in systems exposed to ionizing radiation.

Los estilos APA, Harvard, Vancouver, ISO, etc.

47

Aldalbahi, Adel, Farzad Shahabi y Mohammed Jasim. "Instantaneous Beam Prediction Scheme against Link Blockage in mmWave Communications". Applied Sciences 11, n.º 12 (17 de junio de 2021): 5601. http://dx.doi.org/10.3390/app11125601.

Texto completo

Resumen

Millimeter wave (mmWave) bands formulate the standalone (SA) operation mode in the new radio (NR) access technology of 5G systems. These bands rely on beamforming architectures to aggregate antenna array gains that compensate for dynamic channel fluctuations and propagation impairments. However, beamforming results in directional transmission and reception, thus resulting in beam management challenges, foremost initial access, handover, and beam blockage recovery. Here, beam establishment and maintenance must feature ultra-low latencies in the control and data planes to meet network specifications and standardization. Presently, existing schemes rely on arrays redundancy, multi-connectivity, such as dual-beam and carrier aggregation, and out-of-band information. These schemes still suffer from prolonged recovery times and aggregated power consumption levels. Along these lines, this work proposes a fast beam restoration scheme based on deep learning in SA mmWave networks. Once the primary beam is blocked, it predicts alternative beam directions in the next time frame without any reliance on out-of-band information. The scheme adopts long short-term memory (LSTM) due to the robust memory structure, which uses past best beam observations. The scheme achieves near-instantaneous recovery times, i.e., maintaining communications sessions without resetting beam scanning procedures.

Los estilos APA, Harvard, Vancouver, ISO, etc.

48

Al-Samman, Ahmed, Tharek Rahman, MHD Hindia, Abdusalama Daho y Effariza Hanafi. "Path Loss Model for Outdoor Parking Environments at 28 GHz and 38 GHz for 5G Wireless Networks". Symmetry 10, n.º 12 (29 de noviembre de 2018): 672. http://dx.doi.org/10.3390/sym10120672.

Texto completo

Resumen

It has been widely speculated that the performance of the next generation Internet of Things (IoT) based wireless network should meet a transmission speed on the order of 1000 times more than current wireless networks; energy consumption on the order of 10 times less and access delay of less than 1 ns that will be provided by future 5G systems. To increase the current mobile broadband capacity in future 5G systems, the millimeter wave (mmWave) band will be used with huge amounts of bandwidth available in this band. Hence, to support this wider bandwith at the mmWave band, new radio access technology (RAT) should be provided for 5G systems. The new RAT with symmetry design for downlink and uplink should support different scenarios such as device to device (D2D) and multi-hop communications. This paper presents the path loss models in parking lot environment which represents the multi-end users for future 5G applications. To completely assess the typical performance of 5G wireless network systems across these different frequency bands, it is necessary to develop path loss (PL) models across these wide frequency ranges. The short wavelength of the highest frequency bands provides many scatterings from different objects. Cars and other objects are some examples of scatterings, which represent a critical issue at millimeter-wave bands. This paper presents the large-scale propagation characteristics for millimeter-wave in a parking lot environment. A new physical-based path loss model for parking lots is proposed. The path loss was investigated based on different models. The measurement was conducted at 28 GHz and 38 GHz frequencies for different scenarios. Results showed that the path loss exponent values were approximately identical at 28 GHz and 38 GHz for different scenarios of parking lots. It was found that the proposed compensation factor varied between 10.6 dB and 23.1 dB and between 13.1 and 19.1 in 28 GHz and 38 GHz, respectively. The proposed path loss models showed that more compensation factors are required for more scattering objects, especially at 28 GHz.

Los estilos APA, Harvard, Vancouver, ISO, etc.

49

Lup, Aurel-Sorin, Gabriela Ciuprina, Daniel Ioan, Anton Duca, Alexandra Nicoloiu y Dan Vasilache. "Physics-aware macromodels for MEMS switches". COMPEL - The international journal for computation and mathematics in electrical and electronic engineering 39, n.º 2 (27 de abril de 2020): 497–509. http://dx.doi.org/10.1108/compel-06-2019-0267.

Texto completo

Resumen

Purpose The purpose of this paper is to propose a physics-aware algorithm to obtain radio frequency (RF)-reduced models of micro-electromechanical systems (MEMS) switches and show how, together with multiphysics macromodels, they can be realized as circuits that include both lumped and distributed parameters. Design/methodology/approach The macromodels are extracted with a robust procedure from the solution of Maxwell’s equations with electromagnetic circuit element (ECE) boundary conditions. The reduced model is extracted from the simulations of three electromagnetic field problems, in full-wave regime, that correspond to three configurations: signal lines alone, switch in the up and down positions. Findings The technique is exemplified for shunt switches, but it can be extended for lateral switches. Moreover, the algorithm is able take frequency dependence into account both for the signal lines and for the switch model. For the later, the order of the model is increased until a specified accuracy is achieved. Originality/value The use of ECE as boundary conditions for the RF simulation of MEMS switches has the advantage that the definition of ports is unambiguous and robust as the ports are clearly defined. The extraction approach has the advantage that the simplified model keeps the basic phenomena, i.e. the propagation of the signal along the lines. As the macromodel is realized with a netlist that uses transmission lines models, the lines’ extension is natural. The frequency dependence can be included in the model, if needed.

Los estilos APA, Harvard, Vancouver, ISO, etc.

50

Brown, Samuel J. "Energy Release Protection for Pressurized Systems. Part II: Review of Studies Into Impact/Terminal Ballistics". Applied Mechanics Reviews 39, n.º 2 (1 de febrero de 1986): 177–201. http://dx.doi.org/10.1115/1.3143704.

Texto completo

Resumen

In order to assess whether or not there is a need for protection against the failure of a pressure system, the engineer must evaluate the hazards associated with rupture. The hazards are divided into two categories: (a) force/displacement and (b) degenerative. Force/displacement is classified into (1) kinetic energy associated with the atmosphere: blast, (2) kinetic energy of objects (fragmentation and impact of missiles), and (3) kinetic energy associated with foundations: soil foundation motion. The first article of this series [Energy release protection from pressurized systems: Part I Review of studies into blast and fragmentation, Appl Mech Rev38 (Dec), 1625–1651 (1985)] has set the stage for this paper, which reviews the studies into predicting the performance (mechanics) of a receptor (target, containment, barricade, shelter) that is impacted by a missile. The study into the prediction of target missile performance or terminal ballistics has occupied interests of man since the development of a projectile as a weapon. One of the earliest publications of terminal ballistics is reported by Robins (1742). A number of experimental studies during the 1800s are reported by Holie (1950). These early experiments set the pattern for the reliance on experimental programs to define semiempirical formula to predict missile–target responses (such as penetration, perforation, spalling, and scabbing) into the 20th century. This is due to the fact that theoretically derived equations to predict missile target performance have enjoyed only limited success because of the complexity of the problems to be solved. Numerical methods essentially had to wait for the development of the high speed digital computers in the early 1960s. Historically the finite difference methods have received the earliest use in simulating impact. They tend to be more computationally cost effective than finite element programs. However, because of the generality of the finite element method to idealize structures geometrically for a considerable range of mechanics problems, it has received the greater attention of research and development over the last two decades and is capable of solving wave propagation, nonlinear material, and nonlinear large deformation problems. The computer codes developed to solve impact problems are generally characterized as either Lagrangian or Eulerian. In this paper, a brief discussion will be provided covering the development of target/missile formulas, associated experimental programs and numerical methods.

Los estilos APA, Harvard, Vancouver, ISO, etc.

Artículos de revistas sobre el tema "Radio wave propagation – Computer programs"

Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros