Optical communication has been employed in a wide range of applications, including terrestrial, submarine, inter-satellite, and even space communication. It is particularly successful fiber-based networks that vastly reshape modern life through the Internet. With intensified activities such as undersea resource exploration, ecosystem monitoring, recreation, underwater an exciting new arena for optical wireless (OWC). In this paper, we review recent progress water-air OWC systems. Channel...

Underwater optical wireless communication (UOWC) is of great interest to the academic and industry community. In this article, we propose a low-complexity effective joint transmitter-side digital signal processing (DSP) including geometric shaping, time-domain tone reservation (TR), clipping. The peak-to-average power ratio reduction performance implementation complexity proposed TR are extensively analyzed. We then develop real-time 2.2-Gb/s system, which optimized for its shaping clipping...

We propose a novel subcarrier and power allocation method to improve both the throughput user fairness in orthogonal frequency division multiplexing non-orthogonal multiple access visible light communication (OFDM-NOMA VLC) systems. The proposed considers various constraints practical VLC systems, including bandwidth limitation, non-negative optical signal, peak for eye safety, quality of service. adopts log utility function is applicable cases where number multiplexed users on each not...

The catalytic conversion of biomass-derived fatty acids into iso-alkanes is a promising approach for producing high-quality renewable biofuels. Herein, Ni catalysts on nanocrystal ZSM-22 (xNi/N-ZSM-22, x represents loading) featuring an abundance mesoporous structure and numerous accessible 10-member ring (10-MR) openings are prepared, then tested converting palmitic acid long-chain through single-step process involving deoxygenation hydroisomerization reactions. catalyst with loading 3.0...

To enable flexible service provisioning in elastic optical networks (EONs), quality of transmission (QoT) estimation and dynamic routing spectrum assignment (RSA) are critical network management tasks. Recently, machine learning approaches have been extensively investigated to address these tasks individually. We propose take an integrative approach design a Pointer Network (PtrNet)-based QoT-aware RSA (PtrNet-RSA) scheme optimize the blocking probability generalized signal-to-noise ratio...

In a water-air optical wireless communication (OWC) channel, dynamic ocean waves may significantly deflect the light beam from its original direction, thus deteriorating performance. this letter, tracking system to mitigate wave-induced degradation is experimentally demonstrated. By employing on PAM6 system, maximum of 486% improvement (from 140 Mb/s 820 Mb/s) in throughput realized at 1.2-m air distance for an average wave slope changing rate 0.34 rad/s. For PAM4 signals, packet loss...

We demonstrated a diversity-reception lens-free underwater wireless optical communication system employing 2×2 solar panel array as detectors. The respective relationships between sizes and photocurrents, output voltages, bandwidths were studied theoretically experimentally. signals from the combined via maximum ratio combining in order to improve signal quality. A 450-nm blue laser was used transmitter light spot with size of 20mm×35mm formed on receiving plane after 7-m transmission tap...

In next-generation centralized or cloud radio access networks (C-RANs), time and wavelength division multiplexed passive optical network (TWDM-PON) has been well recognized as a promising candidate to build the mobile fronthaul. Considering stringent bandwidth efficiency, latency, cost requirements in C-RAN, an efficient allocation scheme is highly desirable for TWDM-PON-based Especially massive multiple input outputs (mMIMO) enabled beamforming scenario, additional resource required be...

As a fast and non-destructive spectroscopic analysis technique, Raman spectroscopy has been widely applied in chemistry. However, noise is usually unavoidable spectra. Hence, denoising an important step before spectral analysis. A novel method based on variational mode decomposition (VMD) was introduced to solve the above problem. The spectrum decomposed into series of modes (uk) by VMD. Then, high-frequency are removed remaining reconstructed obtain denoised spectrum. proposed verified two...

Orthogonal frequency division multiplexing non-orthogonal multiple access (OFDM-NOMA) is a promising multi-user scheme in indoor visible light communication (VLC) systems. In this paper, we propose three novel joint subcarrier and power allocation algorithms OFDM-NOMA-VLC to improve the throughputs and/or user fairness. These proposed address requirements fairness-throughput-balanced (FTB), fairness-first (FF), throughput-first (TF) scenarios, respectively. All of them objective function...

We proposed and experimentally demonstrated the first blue-green OPA-based WDM-VLC systems with narrow channel spacing. A 4.5-Gbit/s transmission 50% capacity enhancement was achieved by OCT-precoding simplified third-order Volterra equalization.

We demonstrate the performance of Discrete-Circulant-Transform-spread-OFDM OWC system through a wavy air-water surface. The results show that scheme can mitigate induced power fading, and packet loss rate be significantly reduced from 23.0% to 5.5%.

This paper summarizes the recent trend and progress of underwater water-air optical wireless communications. Channel characterization, communication system performance, effective mitigation methods under influence bubble wave are discussed.

As a fast and nondestructive spectroscopic analysis technique, Raman spectroscopy has been widely applied in chemistry. However, noise is usually unavoidable spectra. Hence, denoising an important step before spectral analysis. A novel method based on variational mode decomposition (VMD) was introduced to solve the above problem. The spectrum decomposed into series of modes (uk) by VMD. Then, high frequency are removed remaining reconstructed obtain denoised spectrum. proposed verified two...

Real-valued OCT precoding to achieve CSI-free linear equalization is proposed for fast-OFDM VLC. We show SNRs over subcarriers can be equalized approximately the harmonic mean of original SNRs, and >35% capacity improvement achieved.

We propose and experimentally demonstrate a capacity-approaching scheme via joint probabilistic shaping (PS) precoding in an optical wireless communication (OWC) system. Different from the bit-and-power- entropy-loading schemes, proposed only requires one modulation format with single-PS distribution while offering ability of maximizing system's throughput. Moreover, we show that also exhibits superior spectral efficiency (SE) generalized mutual information (GMI) performances. As result,...

We experimentally demonstrated a reliable water-air optical wireless link with fast-tracking system to combat the wave-induced beam deflection. A maximum packet loss rate reduction from 6.04% 0.63% is achieved for 50-Mbps signal.

We systematically investigate the bubble-induced performance degradation for underwater optical wireless communication (UOWC) with different bubble sizes and positions. By using transmit receive diversities, we effectiveness of spatial diversity on mitigation impairment to UOWC link. With help a 2 × multiple input output repetition coding maximum ratio combining, robust 780 Mbit/s transmission is achieved. The corresponding outage probability can be significantly reduced from 34.6% system...

We demonstrated a proactive adaptive loading scheme for air-water SIMO OWC systems through waves based on the prediction of wave characteristics. A maximum 96.2% increase in throughput is realized by temporal and spatial diversities.

A 5000m3 single deck floating roof crude oil storage tank was found to have a cracked Q345R bottom plate during an open inspection. To analyze the cause of failure, series experiments were carried out. The results showed that chemical composition failed material had slight excess S, V, and Ti which causes form bainite structure, resulting in hard brittle with poor toughness. is susceptive H2S stress corrosion cracking according SCC test. Based on working condition investigation, subjected...

We investigate spatial diversity schemes for robust VLC to accommodate fast-moving terminals. Results show that the proposed MISO-VLC system exhibits superior robustness receiver's mobility and achieves 4-Gb/s transmissions at 1-m/s terminal moving speed.

We propose and experimentally characterize a modified fractional DFT matrix robust channel processor for FTN-NOFDM visible light communication systems without complex upconversion. A 1.76-Gb/s signal with 20% reduced bandwidth achieves ~6-dB sensitivity improvement over 2-m free-space transmission.

Abstract Bifunctional catalysts are widely used in the hydroisomerization of long‐chain n ‐alkanes, which great significance production high value‐added chemicals. Herein, Ni/ZSM‐23‐W and Ni/ZSM‐23‐EG were prepared using water ethylene glycol, respectively. The characterized XRD, SEM, TEM, NH 3 ‐TPD, Py–IR, H 2 ‐TPR, ICP–OES, XPS, their catalytic performance was evaluated by conducting ‐hexadecane as a model reaction. It revealed that polarity impregnating solvent has significant impact on...

We proposed and experimentally demonstrated the first blue-green OPA-based WDM-VLC systems with narrow channel spacing. A 4.5-Gbit/s transmission 50% capacity enhancement was achieved by OCT-precoding simplified third-order Volterra equalization.