- 标题
- 摘要
- 关键词
- 实验方案
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Singular Atmospheric Optics: From Wavefront Dislocations to Synthesis of Vortex Laser Beams
摘要： Studies on the singular optics of scalar wave fields carried out in the world and at V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences (IAO SB RAS) are reviewed. The study results of the processes of origination and annihilation of phase singularities are generalized. The methods for singular phase reconstruction and their applicability to the problems of adaptive focusing of radiation in randomly inhomogeneous media are examined. The energy, statistical, and topological properties of vortex optical beams propagating through a turbulent atmosphere are analyzed. The results of the synthesis of vortex beams with quickly controllable orbital angular momentum by the matrix approach developed at IAO SB RAS are described.
关键词： vortex beam,turbulent atmosphere,probability density function,intensity fluctuations
更新于2025-09-19 17:13:59
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Exact distributions for bit error rate and channel capacity in free-space optical communication
摘要： Bit error rate (BER) and channel capacity are two important metrics to assess the performance of free-space optical communication (FSOC) systems. Due to the fading of the optical signal owing to the atmospheric effects, these two quantities behave as random variables. Most of the studies in this direction have focused on the calculation of only the average of these quantities. However, since the complete information about a random variable is encoded in its distribution, it is more informative to examine the latter itself. In this work, the authors derive exact probability density function (PDF) expressions for the BER and the channel capacity for an arbitrary irradiance model. In particular, they investigate these exact results for log-normal, gamma-gamma, and K distributions. For the BER analysis, they focus on the binary phase shift keying and quadrature phase shift keying modulation schemes. The authors' analytical reults are found to be in conformity with Monte Carlo simulations. The exact PDFs of the BER and the channel capacity reveal that there are several instances when the average is unable to capture the actual behaviour of these quantities, and therefore one must be careful in drawing conclusions based on the first moment only.
关键词： binary phase shift keying,bit error rate,quadrature phase shift keying,gamma-gamma distribution,channel capacity,log-normal distribution,K distribution,probability density function,free-space optical communication
更新于2025-09-12 10:27:22
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Experimental study of the effects of thermally induced optical turbulence on underwater wireless optical communication link parameters
摘要： In this experimental research, the effects of refractive index fluctuations resulting from temperature fluctuations on some of the most important underwater communication link parameters such as the average received power, Signal to Noise Ratio (SNR) and normalized power variance (aperture averaged scintillation) has been experimentally investigated. Moreover, by introducing a new probability density function which is fitted more appropriately to the experimental data obtained from our simulator tank, the Bit Error Rate (BER) behavior of an Underwater Wireless Optical Communication (UWOC) link is also studied. These investigations are essential due to the optical turbulence limiting effects on the performance of UWOC systems. The experimental results indicate that reduction of the aperture averaged scintillation effects by using of optical components in the transmitter and receiver of UWOC links can enhance their performance. In general, increasing the strength of the optical turbulence (by increasing the temperature gradient induced by the rod heater) or the distance of the localized turbulence screen generated by temperature gradient from the transmitter plane, the aperture averaged scintillation decreases and consequently the SNR raises whilst the BER declines. Also, expanding the aperture diameter of the receiver optics reduces the normalized power variance which leads to decrease and increase in the BER and the SNR amounts respectively. The results are presented as experimental simulation graphs.
关键词： Laser beam propagation through turbulence,aperture averaged scintillation,Probability density function,BER,SNR,Underwater optical communication link
更新于2025-09-12 10:27:22
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Modeling and Experimental Study of the Vibration Effects in Urban Free-Space Optical Communication Systems
摘要： Free-space optical (FSO) communication, considered as a last-mile technology, is widely used in many urban scenarios. However, the performance of urban free-space optical (UFSO) communication systems fades in the presence of system vibration caused by many factors in the chaotic urban environment. In this paper, we develop a dedicated indoor vibration platform and atmospheric turbulence to estimate the Bifurcated-Gaussian (B-G) distribution model of the receiver optical power under different vibration levels and link distances using nonlinear iteration method. Mean square error (MSE) and coef?cient of determination (R2) metrics have been used to show a good agreement between the PDFs of the experimental data with the resulting B-G distribution model. Besides, the UFSO channel under the effects of both vibration and atmospheric turbulence is also explored under three atmospheric turbulence conditions. Our proposed B-G distribution model describes the vibrating UFSO channels properly and can easily help to perform and evaluate the link performance of UFSO systems, e.g., bit-error-rate (BER), outage probability. Furthermore, this work paves the way for constructing completed auxiliary control subsystems for robust UFSO links and contributes to more extensive optical communication scenarios, such as underwater optical communication, etc.
关键词： Urban free-space optical (UFSO) communication,probability density function (PDF),Bifurcated-Gaussian distribution,vibration analysis,received optical power
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Photonics Conference (IPC) - San Antonio, TX, USA (2019.9.29-2019.10.3)] 2019 IEEE Photonics Conference (IPC) - Probability Distribution of Intercore Crosstalk in Weakly Coupled MCFs with Multiple Interferers
摘要： The statistical behavior of the intercore crosstalk (ICXT) power in weakly coupled multicore fibers (MCFs) with multiple interfering cores is experimentally assessed. The histograms with multiple interfering cores are compared with the probability density function (pdf) of the quadratic form corresponding to the ICXT power considering different correlation coefficients between the in-phase and quadrature Gaussian ICXT field components of the orthogonal polarizations. A very good fitting between experimental histograms and the numerical pdf of the quadratic form occurs when the ICXT field components are modeled as uncorrelated random processes. These results demonstrate that the ICXT power can, with a very low error, be described by a chi-square distribution with 4 degrees of freedom not only with a single interfering core but also with multiple interfering cores. This means that the ICXT contributions induced by different cores of the MCF are uncorrelated.
关键词： Multicore fiber,probability density function,space division multiplexing,multiple interferers
更新于2025-09-11 14:15:04
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[IEEE 2018 IEEE Canadian Conference on Electrical & Computer Engineering (CCECE) - Quebec, QC, Canada (2018.5.13-2018.5.16)] 2018 IEEE Canadian Conference on Electrical & Computer Engineering (CCECE) - Accommodating High Penetration of PV in Distribution Networks Considering Smart Curtailment
摘要： This paper presents an approach for photo-voltaic based DG allocation in distribution networks. The objective of the proposed approach is to minimize the developer’s investment cost associated with energy supply requirements over predefined planning period. Uncertainties associated with supply and demand are considered in this work, as well as, the uncertainty associated with energy prices. In addition, this work introduces smart curtailment of renewable resources, which can maximize the penetration and minimize the overall investment. Simulation results on a typical distribution network are provided, which prove the effectiveness and robustness of the proposed resource allocation approach.
关键词： distributed generation,renewable resources,probability density function,genetic algorithms,smart grids
更新于2025-09-09 09:28:46
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[IEEE 2018 15th European Radar Conference (EuRAD) - Madrid, Spain (2018.9.26-2018.9.28)] 2018 15th European Radar Conference (EuRAD) - Quality Analysis of Antenna Reflection Coefficient in Massive MIMO Antenna Array Module
摘要： Number of antennas per an antenna module will increase in upcoming 5G millimeter wave (mmW) radio products. The usage of antenna arrays compensates the increased propagation loss of a radio signal at mmW frequencies. The worst performing antenna defines the quality level MIMO antenna module. This paper presents an analysis and a relationship between the variation of the antenna resonance frequency and the reflection coefficient. A probability density function (PDF) of the antenna reflection coefficient at the specification limit is a non- linearly scaled mirrored version of the PDF of the variation of the antenna resonance. We measured the PDF of antenna reflection coefficient from manufactured prototypes and there is a good correlation between the measured and the simulated PDFs.
关键词： 5G,Antenna,Impedance matching,Process capability index,Probability density function,mmW
更新于2025-09-09 09:28:46
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[IEEE 2018 International Conference on Emerging Trends and Innovations In Engineering And Technological Research (ICETIETR) - Ernakulam, Cochin, India (2018.7.11-2018.7.13)] 2018 International Conference on Emerging Trends and Innovations In Engineering And Technological Research (ICETIETR) - Statistical Analysis of Monthly Solar Radiations and Wind Speed Data
摘要： Increase in electricity demand has motivated us to move towards renewable energy sources. These energy sources are available abundantly and can never be exhausted. Environmental impacts are much lower than those with conventional energy sources. Therefore, in this study, solar and wind data has been collected at Aurangabad, Maharashtra (Latitude: 19o52’ 3.61” N – Longitude: 75o19’ 23.99” E) for a period of one year and statistical analysis has been carried out. Solar radiation data has been recorded to estimate the level of radiations falling on the same location mentioned above, while the wind speed data has been recorded and analyzed using Weibull and Rayleigh distribution and the best fitting distribution of wind has been found out using goodness of fit tests.
关键词： Weibull,Rayleigh,goodness of fit tests,Chi-Squared test,root mean square error,monthly solar radiation,wind speed,probability density function
更新于2025-09-04 15:30:14