Net 835-Gb/s/{\lambda} Carrier- and LO-Free 100-km Transmission Using Channel-Aware Phase Retrieval Reception

We experimentally demonstrate the first carrier- and LO-free 800G/{\lambda} receiver enabling direct compatibility with standard coherent transmitters via phase retrieval, achieving net 835-Gb/s transmission over 100-km SMF and record 8.27-b/s/Hz net optical spectral efficiency.Comment: 3 pages, 3 figure

Integrative transcriptome and metabolome analysis reveals the mechanisms of light-induced pigmentation in purple waxy maize

IntroductionWaxy maize, mainly consumed at the immature stage, is a staple and vegetable food in Asia. The pigmentation in the kernel of purple waxy maize enhances its nutritional and market values. Light, a critical environmental factor, affects anthocyanin biosynthesis and results in pigmentation in different parts of plants, including in the kernel. SWL502 is a light-sensitive waxy maize inbred line with purple kernel color, but the regulatory mechanism of pigmentation in the kernel resulting in purple color is still unknown.MethodsIn this study, cyanidin, peonidin, and pelargonidin were identified as the main anthocyanin components in SWL502, evaluated by the ultra-performance liquid chromatography (UPLC) method. Investigation of pigment accumulation in the kernel of SWL502 was performed at 12, 17, and 22 days after pollination (DAP) under both dark and light treatment conditions via transcriptome and metabolome analyses.ResultsDark treatment affected genes and metabolites associated with metabolic pathways of amino acid, carbohydrate, lipid, and galactose, biosynthesis of phenylpropanoid and terpenoid backbone, and ABC transporters. The expression of anthocyanin biosynthesis genes, such as 4CL2, CHS, F3H, and UGT, was reduced under dark treatment. Dynamic changes were identified in genes and metabolites by time-series analysis. The genes and metabolites involved in photosynthesis and purine metabolism were altered in light treatment, and the expression of genes and metabolites associated with carotenoid biosynthesis, sphingolipid metabolism, MAPK signaling pathway, and plant hormone signal transduction pathway were induced by dark treatment. Light treatment increased the expression level of major transcription factors such as LRL1, myc7, bHLH125, PIF1, BH093, PIL5, MYBS1, and BH074 in purple waxy maize kernels, while dark treatment greatly promoted the expression level of transcription factors RVE6, MYB4, MY1R1, and MYB145.DiscussionThis study is the first report to investigate the effects of light on waxy maize kernel pigmentation and the underlying mechanism at both transcriptome and metabolome levels, and the results from this study are valuable for future research to better understand the effects of light on the regulation of plant growth

Kernel Joint Sparse Representation Based on Self-Paced Learning for Hyperspectral Image Classification

By means of joint sparse representation (JSR) and kernel representation, kernel joint sparse representation (KJSR) models can effectively model the intrinsic nonlinear relations of hyperspectral data and better exploit spatial neighborhood structure to improve the classification performance of hyperspectral images. However, due to the presence of noisy or inhomogeneous pixels around the central testing pixel in the spatial domain, the performance of KJSR is greatly affected. Motivated by the idea of self-paced learning (SPL), this paper proposes a self-paced KJSR (SPKJSR) model to adaptively learn weights and sparse coefficient vectors for different neighboring pixels in the kernel-based feature space. SPL strateges can learn a weight to indicate the difficulty of feature pixels within a spatial neighborhood. By assigning small weights for unimportant or complex pixels, the negative effect of inhomogeneous or noisy neighboring pixels can be suppressed. Hence, SPKJSR is usually much more robust. Experimental results on Indian Pines and Salinas hyperspectral data sets demonstrate that SPKJSR is much more effective than traditional JSR and KJSR models

Photo-Generation of Tunable Microwave Carriers at 2 µm Wavelengths Using Double Sideband with Carrier Suppression Modulation

At 2 µm wavelengths (149.9 THz), hollow-core photonics band gap fibers have higher light power damage thresholds, stable polarization states, and lower losses of 0.1 dB/km. Additionally, a thulium-doped fiber amplifier can provide a gain of >35 dB. Specifically, an indium-rich InGaAs photodetector shows a naturally higher photoresponsivity at 2 µm wavelengths than the C-band. Therefore, using tunable photo-generated microwave technology at 2 µm wavelengths could achieve higher photo-to-electric power conversion efficiencies for higher RF output power applications using the same method at the same frequency. Here, a double sideband with the carrier suppression modulation method was experimentally applied on 2 µm wavelengths to generate tunable and stable microwave carriers. Comparison experiments were also applied on the 1.55 µm (193.4 THz)/1.31 µm wavelengths (228.8 THz) based on the same indium-rich InGaAs photodetector. Through normalization on the wavelength-corresponded squared external quantum efficiency to visualize the photo-to-electric power conversion efficiency at different wavelengths under the same input optical signal power, the ratio between the results at 2 µm wavelengths and C/O-band is abstracted as 1.31/1.98, approaching theoretical estimations. This corresponds to a power conversion efficiency increasement of ~1.16 dB/~2.98 dB. To our knowledge, this is the first study on 2 micron wavelengths that proves the corresponding high efficiency power conversion property

Generation of Frequency-tunable Microwave Carriers based on the U-band Lightwave Carrier

【Objective】High-frequency microwave carriers (GHz) with tunable capability have a wide range of applications in 5th Generation Mobile Communication Technology (5G)/ 6th Generation Mobile Communication Technology (6G) wireless networks, radar systems, and satellite communications. Due to the relatively simple structure of the system, the large bandwidth and the low loss, the technical scheme of generating high-frequency tunable microwave carriers based on photonic technology has attracted extensive attention from domestic and international research teams. Current photogenerated microwave experiments are mostly conducted in C-band wavelengths because of the mature commercial devices. Meanwhile, the Wavelength Division Multiplexing (WDM)-Radio Over Fiber (ROF) technology integrates the WDM technology with the ROF technology so as to flexibly realize the combining/splitting of microwave bands with the help of the combining/splitting of WDM system in the optical frequency domain. The ROF part of the system employs photogenerated microwave technology to simplify the base station configuration. Constrained by the limited bandwidth resources in the C-band wavelengths(35 nm, 1 530~1 565 nm), there is a drive for the generation of microwave to expand to wider spectral ranges. The U-band wavelengths can also provide channel bandwidths as wide as 50 nm (1 625~1 675 nm) to alleviate the channel utilization pressure in the C-band wavelengths; In the U-band wavelengths, Standard Single Mode Fibers(SSMFs) have achieved optical power loss as low as 0.195 dB/km (@1 625 nm); In particular, thulium-doped fiber amplifiers have also demonstrated a large bandwidth gain of 18.7 dB (@1 655 nm). These advantages attract SSMFs-based WDM systems to expand into the U-band, which leads to the extension of WDM-ROF technology into long wavelengths, and in turn leads to the expansion of photogenerated microwave technology. Therefore, this paper studies the photogenerated microwave technology in the U-band.【Methods】From the mathematical model, the commonly used photogenerated microwave carriers technologies are transparent to the applied optical carrier bands, and can be used to generate microwave carriers at arbitrary bands by selecting photonics devices corresponding to the operating bands. In principle, C-band wavelengths photonics devices (such as polarization controllers, Phase Modulator (PM), Fiber Phase Shifter (FPS), etc.) can work in the U-band, and the process technology of these devices is mature. Therefore, in this paper, photonics devices such as C-band wavelengths PM, FPS and optocouplers are used to build a photogenerated microwave carrier system based on U-band optical carriers.【Results】Finally, tunable microwave carrier with a tuning range of 7.5~12.0 GHz and a spurious rejection ratio of 29.6~35.2 dB is ultimately generated based on this system.【Conclusion】Through formula principle analysis and experimental verification, this paper extends the working band wavelengths of the photogenerated microwave carrier to the U-band wavelengths

Transfer learning assisted deep neural network for OSNR estimation

We propose a transfer learning assisted deep neural network (DNN) method for optical-signal-to-noise ratio (OSNR) monitoring and realize fast remodel to response to various system parameters changing, e.g. optical launch power, residual chromatic dispersion (CD) and bit rate. By transferring the hyper-parameters of DNN at the initial stage, we can fast response to the channel variation with fewer training set size and calculations to save consumptions. For feature extraction processing, we use amplitude histograms of received 56-Gb/s QPSK signals as the input for DNN at the initial stage, which shows the root mean squared error (RMSE) of OSNR estimation is less than 0.1 dB with the OSNRs ranging from 5 to 35 dB. Then, we change several system parameters and find superior capabilities of fast remodeling and data resource saving with the proposed method. The required training epochs have about four times reduction, and the required training set size is only one-fifth compared to retraining the network without any accuracy penalty. The DNN assisted by transfer learning can save resources and will be beneficial for real-time application on OSNR estimation

A fuzzy control and neural network based rotor speed controller for maximum power point tracking in permanent magnet synchronous wind power generation system

When the wind speed changes significantly in a permanent magnet synchronous wind power generation system, the maximum power point cannot be easily determined in a timely manner. This study proposes a maximum power reference signal search method based on fuzzy control, which is an improvement to the climbing search method. A neural network-based parameter regulator is proposed to address external wind speed fluctuations, where the parameters of a proportional-integral controller is adjusted to accurately monitor the maximum power point under different wind speed conditions. Finally, the effectiveness of this method is verified via Simulink simulatio

A comparison of chemical composition, bioactive components and hypoglycemic activity of Stigma maydis obtained from different growing times

AbstractStigma maydis (SM) possesses remarkable nutritional value due to the presence of health-protective chemical constituents in it. Despite its commercial uses, there is a lack of information on changes in the nutritional profile of SM during Shenke 601 waxy corn development by following four different maturity stages (silking stage; blister stage; milky stage; dough stage). In this study, the ideal times for the development of seven active compounds (polysaccharides, saponin, rutin, luteolin, quercetin, kaempferol and chlorogenic acid) were at the silking stage. The total flavonoid and total phenol content increased as the SM matured. Except for the above-mentioned active compounds, the content of major nutritional components of dough stage was higher than that of three other stages. The extract of Stigma maydis exhibited good α-amylase, α-glucosidase and pancreatic lipase inhibition activities. The ethanolic SM extracts showed better inhibitory effects than aqueous SM extracts with a dose–effect relationship. The hypoglycemic activity of ethanolic extract was higher than that of aqueous extract at each stage. This provided an important basis for the application of SM