With the development of next generation mobile communication and short distance communication, mmWave is becoming more and more critical. The transmission rate and bandwidth of mmWave are greater than that of low frequency band. mmWave can effectively provide large-flow and low-latency service over short distances. Next generation WLAN, such as 802.11ad/ay, already uses mmWave. mmWave uses the directional gain antenna, and beamtracking is performed to determine the new working beam when one end of the communication is displaced. The beamtracking method is designed in detail in 802.11ad /ay: beamtracking is performed after data is sent. This method takes the delay into account, but it is easy to lose packets when nodes move quickly. To address this issue, we design an adaptive beamtracking method (ABT), which adjusts the order of sending data and performing beamtracking according to the number of consecutive beamtracking request. It can take both throughput and delay into account. The simulation results show that the adaptive beamtracking method can achieve the same delay as the beamtracking method in 802.11ad/ay, and the throughput is greater than the beamtracking method in 802.11ad/ay.
Gaining mechanistic insights into the structure-performance relationship connecting the donor and acceptor is essential to the rational design of high performance nonlinear optics (NLO) materials. Here, intramolecular boron/nitrogen (B/N)-locking strategies in combination with various electron-withdrawing groups, R (R = TXO, DPzS, TTR, DPyS, DTC, DSCZ, DMPS and TXO2), are proposed to address this issue. With the decreasing of torsion angles (θ1 and θ2) between donor (TPA) and acceptor (Py-Ph) units, the first hyperpolarizability (β) values are increased 45-65% and 4-27% by intramolecular B/N-locking strategies, respectively. Intriguingly, we also found some good linear correlations between θ1, θ2, and lgβ (where the determination coefficient R2 ranges from 0.84 to 1.00). Meanwhile, between θ1, θ2, and the excited energy (ΔE) of the crucial excited state there have also good correlations, namely, the R2 ranges from 0.80 to 1.00. As a result, given the fact of finding results, one can draw some meaningful insights, namely, intramolecular B/N-locking strategies hold good application perspective for enhancing β, and θ1 and θ2 can serve as effective descriptors in designing high-performance NLO materials based on the D-A architecture system.
Real-world image denoising is a challenging but significant problem in computer vision. Unlike Gaussian denoising on which most existing methods focus, the real-world noise is nonadditive, and the distributions are difficult to model. This leads to unsatisfactory performance when applying a Gaussian denoising approach on real-world denoising problems. In this paper, we propose a simple framework for effective real-world image denoising. Specifically, we investigate the intrinsic properties of the Gaussian denoising prior and demonstrate this prior can aid real-world image denoising. To leverage this prior, we fine-tune it for only one epoch on a recently proposed real-world image denoising dataset, and the learned model can enhance both visual and quantitative results (peak-signal-noise-ratio) for real-world image denoising tasks. Extensive experiments demonstrate the effectiveness of our approach, and indicate that the Gaussian denoising prior can be also transferred to real-world image denoising by exploiting appropriate training schemes.
In wireless network simulation, the accuracy of the simulation for higher layer communication protocols heavily depends on the quality of PHY layer (physical layer) modeling and simulation. However, the precision of OPNET modeling doesn’t meet the need of wireless network simulation. In order to model and simulate the fundamentals of PHY layer accurately, the adverse effect upon the simulation accuracy is analyzed, which is deriving from the inward deficiencies of the original OPNET PHY layer simulation mechanism, such as inauthenticity of wireless channel and inaccuracy of transceiver working. Moreover, combining the fundamentals of PHY layer, an effective improved method to make up insufficiencies cased by OPNET modeling mechanism is proposed. This method optimizes the ways of modeling the wireless channel, transceiver mechanism, calculation of frame-error rate (FER), and so on. Indicated from the simulation results, the innovated method for PHY layer modeling and simulation is able to remarkably improve the accuracy of the OPNET pipeline stage simulation mechanism.
This paper introduced ITU-R TG 5/1 task group, as well as the current research situation, especially illustrated some interference scenario. Based on 5G high frequency candidate band, radio communication services and the electromagnetic compatibility analysis work, we studied all recommendations and reports related to candidate sub bands, and then classified three very important sub-bands’ recommendations and reports, which had played a positive role in promoting 5G high-frequency candidate band radio interference coexistence analysis research.
Organic selenides are famous for their coordination and catalytic functions in the organic phase, albeit challenging for aqueous medium. Herein, the combination of a hydrophilic body of crown ether and substitution of one oxygen atom with a selenium one provides a new type of design route for organic selenide entities with charming functions in aqueous solution. The selenacrown ether C9Se presented here intrinsically shows an amphiphile-like property. Its nanosphere structure in water readily expands the catalysis of organic selenide to aqueous substrates in thiol/disulfide conversion.
Knowing the precise location where data is collected is a key feature for automated road inspection, including pavement surface and subsurface condition evaluation. The accuracy of commercially available GPS systems (5 to 10 meters) is inadequate because data for road inspection is collected at 2.5cm or smaller intervals with sensors mounted on vehicles moving at 30 mph or faster. Video data recorded from a camera mounted on the vehicle can provide additional data registration to landmarks in the scene and previously recorded data. However, using video data poses additional challenges including the collection, processing and visualization of vast amounts of data, temporal and spatial registration among different cameras used at different times, natural clutter from unstructured environments, noise, and missing key data due to occlusion or dropped frames.
Understanding of aqueous solutions is of significance to a wide range of fields. Crown macrocycles emerge as a new generation of model hosts for studying the chemistry of water and aqueous supramolecular chemistry. Herein, we present the oxacrown ether cyanobenzo-21-crown-7 ether (C7CN), and its selenium-containing counterpart selencrown ether C7SeCN possess only one chalcogen atom diverse in structure but exhibits dramatic difference in shape, solvation (e.g., hydration), and consequent thermodynamics of guest binding experimentally. The hydrogen bond strength of Se···H is similar to that of O···H, but theoretical calculations pointed out that there is a prominent electrostatic potential change for the entire molecule caused by Se substitution, which leads to the decrease of the interactions between water clusters and crown macrocycles thermodynamically and kinetically. Results established that C7CN and C7SeCN provide an easy-to-access model pair to exclusively probe water-solute interaction and host pocket wettability change caused by one atom substitution.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
