Quantitative analysis and prediction of the sound field convergence zone in mesoscale eddy environment based on data mining methods

The mesoscale eddy(ME)has a significant influence on the convergence effect in deep-sea acoustic propagation.This paper use statistical approaches to express quantitative relationships between the ME conditions and convergence zone(CZ)characteristics.Based on the Gaussian vortex model,we construct various sound propagation scenarios under different eddy conditions,and carry out sound propagation experiments to obtain simulation samples.With a large number of samples,we first adopt the unified regression to set up analytic relationships between eddy conditions and CZ parameters.The sensitivity of eddy indicators to the CZ is quantitatively analyzed.Then,we adopt the machine learning(ML)algorithms to establish prediction models of CZ parameters by exploring the nonlinear relationships between multiple ME indicators and CZ parameters.Through the research,we can express the influence of ME on the CZ quantitatively,and achieve the rapid prediction of CZ parameters in ocean eddies.The prediction accuracy(R)of the CZ distance(mean R:0.9815)is obviously better than that of the CZ width(mean R:0.8728).Among the three ML algorithms,Gradient Boosting Decision Tree has the best prediction ability(root mean square error(RMSE):0.136),followed by Random Forest(RMSE:0.441)and Extreme Learning Machine(RMSE:0.518).

Research in migration route of hatchery released Chinese shrimp(Fenneropenaeus chinensis) in the Bohai Bay using method of SSR marker

This study provides new insights for the hatchery released Chinese shrimp(Fenneropenaeus chinensis),including proportion,dynamic migration route,after they were released into nature for stock enhancement using a new strategy quite different than ever.Chinese shrimp were sampled at 22 survey stations during two investigation voyages acrossing 74 survey stations in the Bohai Sea from July 16 to August 9 in 2015.Among 289 sampled individuals during the second voyage,totally 155 shrimps were identified as hatchery shrimp released into the Laizhou Bay at mid-May in 2015 based on finger-print of eight SSR(simple sequence repeats)markers,and the proportion of hatchery released shrimp in recapture samples were from 41.30%–85.71%in each station with an average value 53.63%,which verified a previous view point that up to 90%of autumn season Chinese shrimp landing in the Bohai Sea were composed of hatchery released.Meanwhile,the dynamic migration route of hatchery released shrimp revealed that part of released shrimp migrated heading northwest along the west coast of the Bohai Sea up to the Bohai Bay but just remained at the Laizhou Bay until over-wintering migration at midOctober when they initiate over-wintering migration.Present unnatural spring season shrimp fishing model cut the throat of spawner shrimp chance to swim back to their respective spawning plants at each spring,it still no chance to clarify whether the hatchery released shrimp could replenish to the reproduce population and complete a whole life cycle as same as their natural relatives.

Evolving a Bayesian network model with information flow for time series interpolation of multiple ocean variables

Based on Bayesian network (BN) and information flow (IF),a new machine learning-based model named IFBN is put forward to interpolate missing time series of multiple ocean variables. An improved BN structural learning algorithm with IF is designed to mine causal relationships among ocean variables to build network structure. Nondirectional inference mechanism of BN is applied to achieve the synchronous interpolation of multiple missing time series. With the IFBN,all ocean variables are placed in a causal network visually,making full use of information about related variables to fill missing data. More importantly,the synchronous interpolation of multiple variables can avoid model retraining when interpolative objects change. Interpolation experiments show that IFBN has even better interpolation accuracy,effectiveness and stability than existing methods.

Molecular Basis of Unique Branching Phenotypes in Salvia splendens and the Role of PSY

The branching system of higher plants plays a very important role in plant morphogenesis,and the number of branches can directly affect crop yield and the ornamental value of plants.It is a complicated development process involving complex molecular mechanisms.The‘Cailinghong’variety of Salvia splendens is characterized by its great branching ability with the ability to grow into a spherical form naturally,without pinching.To gain insight into the molecular events during the branching development of S.splendens,suppressive subtractive hybridization(SSH)technology was used to screen differentially expressed genes between the erect plant type(strain 35)and the spherical plant type(‘Cailinghong’).In total,96 and 116 unigenes were annotated.Four and eight unigenes up-regulated in‘Cailinghong’and strain 35,respectively,were associated with plant hormone anabolism and signal transduction,suggesting that they participate in the branching process.One of these genes,phytoene synthase(PSY),is a precursor of the new plant hormone group strigolactones.Using the PSY fragment(192 bp)as a template,the cDNA sequence of PSY in S.splendens was cloned and named SsPSY.A relative expression analysis and transgenic test results indicated that SsPSY plays an important role in lateral branch development in‘Cailinghong’.These results provide new insight into the molecular mechanisms underlying branching in S.splendens.

Kähler流形谱几何

本文从谱几何的历史出发,介绍谱几何的起源与波动方程、量子力学的联系,以及Riemann流形特别是Kähler流形的谱几何相关问题与中国学者的一些工作.最后两节介绍我们在复射影空间谱刚性以及常全纯截面曲率谱刻画方面的工作.

Sensitivity Experiments on the Poleward Shift of Tropical Cyclones over the Western North Pacific under Warming Ocean Conditions

Recent studies found that in the context of global warming, the observed tropical cyclones （TCs） exhibit signific-ant poleward migration trend in terms of the mean latitude where TCs reach their lifetime-maximum intensity in the western North Pacific （WNP）. This poleward migration of TC tracks can be attributed to not only anthropogenic for-cing （e.g., continuous increase of sea surface temperature （SST））, but also impacts of other factors （e.g., natural vari- ability）. In the present study, to eliminate the impacts of other factors and thus focus on the impact of unvaried SST on climatological WNP TC tracks, the mesoscale Weather Research and Forecasting （WRF） model is used to con- duct a suite of idealized sensitivity experiments with increased SST. Comparisons among the results of these experi- ments show the possible changes in climatological TC track, TC track density, and types of TC track in the context of SST increase. The results demonstrate that under the warmer SST conditions, the climatological mean TC track sys-tematically shifts poleward significantly in the WNP, which is consistent with the previous studies. Meanwhile, the ocean warming also leads to the decreased （increased） destructive potential of TCs in low （middle） latitudes, and thus northward migration of the region where TCs have the largest impact. Further results imply the possibility that under the ocean warming, the percentage of TCs with westward/northwestward tracks decreases/increases distinctly.

Impact of Initial Storm Intensity and Size on the Simulation of Tropical Cyclone Track and Western Pacific Subtropical High Extent

Typhoon Megi, the 13th typhoon of the 2010 typhoon season, was selected for case study by utilizing the Weather Research and Forecasting （WRF） model. Twelve sensitivity experiments with various initial tropical cyclone （TC） in- tensities and sizes were conducted to investigate their impacts on the simulation of typhoon track. Interaction between TC and the western Pacific subtropical high （WPSH） was also analyzed to explore the mechanism for the impact on TC track of the initial TC intensity and size. Numerical results indicate that the simulated TC size and TC track are sensitive to initial TC intensity and size. Stronger initial TC intensity and larger initial TC size often lead to larger simulated TC size and make TC turn northward earlier. Further analysis suggests that, with the increase of ini- tial TC intensity and size, more air mass enters into the TC region, which subsequently reduces the extent of WPSH. As a result, the steering flow changes significantly and eventually causes the TC to turn northward earlier. The present study confirms that the initial TC intensity and size have certain influences on the TC track simulation, which demonstrates the importance of accurate initial condition for successful simulation of the TC intensity and TC track. Moreover, it also deepens our understanding of the interaction between TC and WPSH, provides helpful clues for the TC track change study, and discusses the future directions for improvement of TC track forecast.

Remarks on BCOV invariants and degenerations of Calabi-Yau manifolds

For a one parameter family of Calabi-Yau threefolds, Green et al.(2009) expressed the total singularities in terms of the degrees of Hodge bundles and Euler number of the general fiber. In this paper,we show that the total singularities can be expressed by the sum of asymptotic values of BCOV(BershadskyCecotti-Ooguri-Vafa) invariants, studied by Fang et al.(2008). On the other hand, by using Yau's Schwarz lemma, we prove Arakelov type inequalities and Euler number bound for Calabi-Yau family over a compact Riemann surface.

Logarithmic vanishing theorems for effective q-ample divisors

Let X be a compact K?hler manifold and D be a simple normal crossing divisor. If D is the support of some effective q-ample divisor, we show H^i(X, ?_X^j (log D)) = 0, for i + j > n + q.

Harmonic 2-forms and positively curved 4-manifolds

We prove that if a compact Riemannian 4-manifold with positive sectional curvature satisfies a strengthened Kato type inequality,then it is definite.We also discuss some new insights for compact Riemannian 4-manifolds with positive sectional curvature.

Deformations of complex orbifolds and the period maps

We consider the deformations of complex orbifolds with the underlying smooth structures being fixed.As a corollary,we can prove that the deformations of a Calabi-Yau orbifold is unobstructed by using standard arguments.Then we consider the period map for a family of complex Kahler orbifolds.We prove that the period map is holomorphic,horizontal and consistent with our Kodaira-Spencer map.