The application of unmanned aerial vehicles (UAVs) to emerging communication systems has attracted a lot of research interests due to the advantages of UAVs, such as high mobility, flexible ...deployment, and cost-effectiveness. The UAV-carried base stations (UAV-BS) can provide on-demand service to users in temporary or emergency events. However, how to optimize the communication performance of a UAV-BS with a limited-bandwidth wireless backhaul is still a challenge. This paper focuses on improving the spectrum efficiency of a UAV-BS while guaranteeing user fairness under in-band backhaul constraint. We propose to maximize the minimum user rate among all the users served by the UAV-BS by jointly optimizing the allocation of bandwidth and transmit power, as well as the trajectory of the UAV-BS. As the formulated problem is non-convex, we propose an efficient algorithm to solve it suboptimally based on the alternating optimization and successive convex optimization methods. Computer simulation results show that the proposed algorithm achieves a significantly higher minimum user rate than the benchmark schemes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this paper, an energy harvesting enabled cooperative non-orthogonal multiple access (NOMA) system for a multi-cell network is investigated. Particularly, during the direct transmission phase, base ...stations send their superposed messages to the near users and far users simultaneously according to a NOMA principle, while the near users act as energy harvesting enabled relays employing a power splitting protocol. During the cooperative phase, the near users transmit their decoded messages to the corresponding far users using harvested energy. Using tools from stochastic geometry, we firstly calculate the signal to interference ratios of the users in each NOMA group including one near user and one far user. Then, the closed-form expressions of the coverage probability, ergodic rate, and energy efficiency are derived respectively. Numerical results validate the derived expressions and show that the energy harvesting enabled cooperative NOMA system in a multi-cell network can improve the coverage probability, ergodic rate, and energy efficiency compared to its counterpart OMA system.
•Demonstrated the effectiveness of the DI-WS-MSSC algorithm in significantly improving the identification success rate.•Enhanced the versatility and applicability of near-infrared crude oil rapid ...evaluation models.•Established a framework for model transferability across platforms to broaden instrument adoption.
Model transfer, also known as instrument standardization, constitutes a fundamental aspect of near-infrared (NIR) technology. Owing to disparities among spectrometers, spectra acquired from identical samples by different instruments may be erroneously classified as belonging to distinct samples. Consequently, spectral databases established on one spectrometer cannot be directly applied to other instruments, thus impeding the widespread adoption of NIR technology. Model transfer algorithms based on factor analysis often compromise spectral integrity, rendering the transferred spectra unsuitable for pattern recognition. To address this challenge and facilitate the universality of NIR spectral databases for crude oil across diverse instrument platforms, this study proposes a novel methodology, Dense Interpolation-Wavelength Shifting-Mean Spectra Subtraction Correction. This method integrates dense interpolation, wavelength alignment, and background compensation techniques. Through meticulous implementation, this approach effectively mitigates spectral deviations induced by instrument discrepancies. Employing the moving window correlation coefficient method, the transferred NIR spectra of crude oil undergo pattern recognition computations within the NIR spectral database established on the primary instrument. The results demonstrate a successful recognition rate exceeding 90 %, indicating the effectiveness of the proposed methodology in improving spectral consistency and enabling robust pattern recognition in NIR analysis of crude oil.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Two similar crude oils (Arab middle crude oil and Arab heavy crude oil) were selected from the MIR spectral library according to their detailed assay data. The moving window correlation coefficients ...of the two very similar crude oils were calculated using the parameters established. It can be seen that some MWR values are less than 0.9450 in the region of 700–720 and 760–770cm−1, the two similar crude oils have been distinguished, although the Q value was 0.9988, and the correlation coefficient of the full spectra as one was near 0.9990. The result shows that the moving window correlation coefficient method can distinguish the MIR spectra of very similar crude oils.
•We collect a total of 330 crude oil samples.•We presented a fast analytical tool for rapid identification of crude oil type.•Compared with NIR, IR method can distinguish highly similar mixed crude oils given in the study.•We study parameters of the moving window correlation coefficient method in the paper.
Based on attenuated total reflectance mid-infrared spectroscopy and moving window correlation coefficient method, a efficient analytical tool is presented for rapid identification of crude oil type. Spectra between highly similar crude oils can be easily distinguished by the spectral searching method. Compared with NIR, IR method can distinguish highly similar mixed crude oils given in the study. Parameters of the moving window correlation coefficient method are studied in the paper.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Total acid number (TAN) is one of the most important parameters for petroleum. The combined use of multivariate calibration and mid-infrared attenuated total reflection spectroscopy allows it to be ...estimated accurately. The calibration models of acid number have been established by partial least-squares (PLS). The predictive ability of the IR technique with regard to the TAN have been explored. The results predicted by this method were very close to those determined by standard methods. Compared with Standards, this method is provided with advantages such as high speed, simplicity, no pretreatment, and good-repeatability.
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IJS, KILJ, NUK, PNG, UL, UM
Communicating in a non-terrestrial network (NTN) has recently emerged as a promising technology to provide global seamless connectivity. Although low earth orbit (LEO) satellites in an NTN have been ...employed for providing ubiquitous coverage and high data rates for ground users, especially in emergent outdoor scenarios, NTN has not been integrated into the design of multi-connectivity for users in a terrestrial network (TN). Inspired by the 3rd Generation Partnership Program (3GPP) suggestion, this paper investigates TN-NTN-combined multi-connectivity downlink multiple-input multiple-output (MIMO) communication system, where each user may simultaneously connect to a base station (BS) in a TN and an LEO satellite in an NTN. Specifically, each user may have four different downlink access modes: served by both an LEO satellite and a BS, served by a BS, served by an LEO satellite, and not scheduled. Zero-forcing beamforming is employed at each LEO satellite to reduce the mutual interference among the satellite's served users, and maximum ratio transmission beamforming is used at each terrestrial BS to enhance the downlink signal strength. By deriving the probability of each access mode and modeling the interference in such a TN-NTN-combined multi-connectivity MIMO system, we obtain a typical user's downlink coverage probability and average achievable data rate. Extensive Monte Carlo simulations are conducted to validate our analytical derivations. Simulation results demonstrate that the user's coverage probability and average achievable data rate can be significantly improved by realizing multi-connectivity with both TN and NTN compared to pure TN or NTN.
Energy harvesting has been recognized as a promising technique with which to effectively reduce carbon emissions and electricity expenses of base stations. However, renewable energy is inherently ...stochastic and intermittent, imposing formidable challenges on reliably satisfying users' time-varying wireless traffic demands. In addition, the probability distribution of the renewable energy or users’ wireless traffic demand is not always fully known in practice. In this paper, we minimize the total energy cost of a hybrid-energy-powered cellular network by jointly optimizing the energy sharing among base stations, the battery charging and discharging rates, and the energy purchased from the grid under the constraint of a limited battery size at each base station. In solving the formulated non-convex chance-constrained stochastic optimization problem, a new ambiguity set is built to characterize the uncertainties in the renewable energy and wireless traffic demands according to interval sets of the mean and covariance. Using this ambiguity set, the original optimization problem is transformed into a more tractable second-order cone programming problem by exploiting the distributionally robust optimization approach. Furthermore, a low-complexity distributionally robust chance-constrained energy management algorithm, which requires only interval sets of the mean and covariance of stochastic parameters, is proposed. The results of extensive simulation are presented to demonstrate that the proposed algorithm outperforms existing methods in terms of the computational complexity, energy cost, and reliability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Flaky alumina was synthesized by a molten-salt method, and spherical boron nitride was prepared by the spray drying method. The thermal grease was prepared by mixing the alumina platelets and the ...spherical boron nitride in dimethyl silicon oil. The alumina platelets and the spherical boron nitride were characterized by scanning electron microscope, transmission electron microscope and X-ray diffraction. The effects of the addition of aluminaplatelets and spherical boron nitride were studied. The results showed that the thermal conductivity increased with the volume fraction of alumina fillers increasing from 20% to 65%, when the alumina filler was replaced with spherical boron nitride, the similar thermal conductivity increase occurred in new thermal grease. When the volume fraction of flaky alumina is 60%,the maximum thermal conductivity is 2.76 W·（m·K）-1
This detailed, up-to-date introduction to heterogeneous cellular networking introduces its characteristic features, the technology underpinning it and the issues surrounding its use. Comprehensive ...and in-depth coverage of core topics catalogue the most advanced, innovative technologies used in designing and deploying heterogeneous cellular networks, including system-level simulation and evaluation, self-organisation, range expansion, cooperative relaying, network MIMO, network coding and cognitive radio. Practical design considerations and engineering tradeoffs are also discussed in detail, including handover management, energy efficiency and interference management techniques. A range of real-world case studies, provided by industrial partners, illustrate the latest trends in heterogeneous cellular networks development. Written by leading figures from industry and academia, this is an invaluable resource for all researchers and practitioners working in the field of mobile communications.
Because the current network music operation mechanism is constantly improving and the matching of music platforms and users is poor, in this paper, the characteristics of digital music are analyzed, ...and the music features, rhythm, tune, intensity, and timbre with the MIDI format are extracted. Then, a music feature information extraction algorithm based on neural networks is proposed, and according to the extracted information of the music style, the B2T model is adopted for intelligent text generation. Finally, test results are given by the style matching rate and ROUGE value, which show that the model is accurate and effective for classification of music and description of related text, and the extraction of music feature information has a certain influence on its intelligent text generation.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
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