A forecasting model for wave heights based on a long short-term memory neural network

To explore new operational forecasting methods of waves,a forecasting model for wave heights at three stations in the Bohai Sea has been developed.This model is based on long short-term memory(LSTM)neural network with sea surface wind and wave heights as training samples.The prediction performance of the model is evaluated,and the error analysis shows that when using the same set of numerically predicted sea surface wind as input,the prediction error produced by the proposed LSTM model at Sta.N01 is 20%,18%and 23%lower than the conventional numerical wave models in terms of the total root mean square error(RMSE),scatter index(SI)and mean absolute error(MAE),respectively.Particularly,for significant wave height in the range of 3–5 m,the prediction accuracy of the LSTM model is improved the most remarkably,with RMSE,SI and MAE all decreasing by 24%.It is also evident that the numbers of hidden neurons,the numbers of buoys used and the time length of training samples all have impact on the prediction accuracy.However,the prediction does not necessary improve with the increase of number of hidden neurons or number of buoys used.The experiment trained by data with the longest time length is found to perform the best overall compared to other experiments with a shorter time length for training.Overall,long short-term memory neural network was proved to be a very promising method for future development and applications in wave forecasting.

Long-term trend analysis of wave characteristics in the Bohai Sea based on interpolated ERA5 wave reanalysis from 1950 to 2020

Reasonably understanding of the long-term wave characteristics is very crucial for the ocean engineering.A feedforward neural network is operated for interpolating ERA5 wave reanalysis in this study,which embodies a detailed record from 1950 onwards.The spatiotemporal variability of wave parameters in the Bohai Sea,especially the significant wave height(SWH),is presented in terms of combined wave,wind wave and swell by employing the 71 years(1950–2020)of interpolated ERA5 reanalysis.Annual mean SWH decreases at−0.12 cm/a estimated by Theil-Sen estimator and 95th percentile SWH reflecting serve sea states decreases at−0.20 cm/a.Inter-seasonal analysis shows SWH of wind wave has steeper decreasing trend with higher slopes than that of swell,especially in summer and winter,showing the major decrease may attribute to the weakening of monsoon.The inner Bohai Sea reveals a general decreasing trend while the intersection connecting with the Yellow Sea has the lower significance derived by Mann-Kendall test.Meanwhile,95th percentile SWH decreases at a higher rate while with a lower significance in comparison with the mean state.The frequencies of mean wave directions in sub-sector are statistically calculated to find the seasonal prevailing directions.Generally,the dominant directions in summer and winter are south and north.A similar variation concerning to SWH,the trend of the mean wave period is provided,which also shows a decrease for decades.

Analysis on the causes of massive stranding of Yellow Sea green tide on Lianyungang and Rizhao coasts in 2022

In 2022,Yellow Sea green tide caused by Ulva prolifera reached a historic minimum and the coastal areas of Shandong Peninsula were less affected.However,the largest amount of seaweed biomass has been washed ashore on Lianyungang and Rizhao coasts since 2015.We studied the development pattern of Yellow Sea green tide in 2022,and analyzed the key environmental factors on the growth and drifting,then discussed the possible reasons that resulted in the massive stranding of green tide biomass in Lianyungang and Rizhao.Results show under the combined influence of the east to southeast winds and currents with shoreward anomalies,green tide drifted to the coastal waters between Shandong and Jiangsu provinces and the distribution areas located westward compared with previous years(2008–2021).Floating U.prolifera rafts from the coastal waters of Binhai and Sheyang drifted continuously into the coastal waters of Lianyungang and Rizhao,providing important supplements for Yellow Sea green tide.Because green tide in 2022 distributed close to the coastal waters,the abundant nutrients might support their continuous high growth rate.In addition,the amount of rainfall around Shandong Peninsula from late June to early July were significantly higher than in previous years,which might promote the development of green tide to some extent.

A Highly Active Pd（Ⅱ） Complex with 1-Tritylimidazole Ligand for Suzuki-Miyaura and Heck Coupling Reactions

A [Pd（1-tritylimidazole）2Cl2] complex was synthesized and characterized by IH and 13C NMR spectroscopy, elemental analysis, and X-ray crystallography. The X-ray analysis confirmed that the Pd（II） has a four-coordinated square planar structure. The palladium complex was used to carry out Suzuki-Miyaura coupling reactions of aryl chlorides with a variety of phenylboronic acids in i-PrOH-H20 （1 ： 1, V ： V） at room temperature and Heck coupling reactions of aryl halides with methyl acrylate in DMF at 110℃. High yields of the cross-coupling products were obtained.

Synthesis and Catalytic Study of Ruthenium Carbene Catalyst Containing a Zn-Porphyrin Ligand

包含 Zn 卟啉 ligand 的钌 carbene 建筑群被开发了。建筑群被 1 H NMR，红外， HRMS 和元素的分析。为石蜡换位反应的钌 carbene 建筑群的催化活动也被调查。建筑群在 35 °C 为关上戒指、生气的换位反应展出了优秀性能。

Synthesis of Quinoline and 1,2,3,4-Tetrahydroquinoline Derivatives from Substituted o-Nitrotoluenes via Cesium-promoted [2＋4] Cycloaddition

一个原子节俭的高度有效的方法从生撤退电子的组和石蜡(丙烯酸的酉旨，丙烯腈，和甲基 acrylates ) 经由的 o 硝基甲苯为喹啉和 1,2,3,4-tetrahydroquinoline 衍生物的合成被开发了一催化底[2 + 4 ] cycloaddition。这简单，快速，并且环境 -- 友好方法为喹啉和 1,2,3,4-tetrahydroquinoline 衍生物的合成提供一条实际小径。开始的材料是容易地可得到的， 37 个产品被获得在对优秀收益好。

Synthesis and Catalytic Activity of a Grubbs-Hoveyda Pre-catalyst Having a Trimeric Resting State

A Grubbs-Hoveyda pre-catalyst having a trimeric resting state based on 2,4,6-trichloro-1,3,5-triazine was syn-thesized and the complex was characterized by NMR,HRMS and elemental analysis.The activity of this complex for ring-closing metathesis(RCM)was investigated.The catalytic system possesses high catalytic activity for many different olefin substrates.

N-Heterocyclic Carbene Copper(Ⅰ)Complex Catalyzed Coupling of(Hetero)aryl Chlorides and Nitrogen Heterocycles:Highly Efficient Catalytic System

of main observation and conclusion A highly efficient catalytic system for the N-arylation reactions of(hetero)aryl chlorides and nitrogen heterocycles with a copper(l)complex containing a 1,10-phenanthroline analogue N-heterocyclic carbene(NHC)has been reported.The complex was characterized by^lH NMR and^13C NMR spectroscopy and elemental analysis,and its structure was determined by single-crystal X-ray diffraction.The NHC-copper(l)complex was employed as pre-catalyst for Ullmann type N-arylation reactions of(hetero)aryl chlorides with various azoles.A variety of hindered and functionalized azoles and(hetero)aryl chlorides were transformed in good to excellent yields.