Modeling of bistatic scattering from an underwater non-penetrable target using a Kirchhoff approximation method

A numerical triangulation and transformation into the time domain of a Kirchhoff approximation(KA)method is proposed for the modeling of bistatic scattering from an underwater non-penetrable target.The time domain solution in this approximation can be split up into two parts:the solution of reflected field,contributing around the specular direction,and the solution of shadow radiation,contributing around the forward direction.An average solution in the time domain satisfying the reciprocity principle is presented.The solution is expressed in terms of non-singular functions.The proposed method is validated against a normal mode method for bistatic scattering from a rigid sphere.Moreover,the reflected and shadow highlights on the surface of the sphere are shown to verify the integration surface of the reflected field and shadow radiation.It is also tested against a finite element method and an experiment involving a scaled Benchmark Target Strength Simulation Submarine model.The time-angle bistatic spectra for the model are evaluated by the direct and transformed average solutions of KA,and the former accelerates its speed of calculation.The results are good,and show that this method can be used to predict the bistatic scattered field of a non-penetrable target.

A Survey on Blocking Technology of Entity Resolution

Entity resolution(ER)is a significant task in data integration,which aims to detect all entity profiles that correspond to the same real-world entity.Due to its inherently quadratic complexity,blocking was proposed to ameliorate ER,and it offers an approximate solution which clusters similar entity profiles into blocks so that it suffices to perform pair-wise comparisons inside each block in order to reduce the computational cost of ER.This paper presents a comprehensive survey on existing blocking technologies.We summarize and analyze all classic blocking methods with emphasis on different blocking construction and optimization techniques.We find that traditional blocking ER methods which depend on the fixed schema may not work in the context of highly heterogeneous information spaces.How to use schema information flexibly is of great significance to efficiently process data with the new features of this era.Machine learning is an important tool for ER,but end-to-end and efficient machine learning methods still need to be explored.We also sum up and provide the most promising trend for future work from the directions of real-time blocking ER,incremental blocking ER,deep learning with ER,etc.

Uniform supertrees with extremal spectral radii

A supertree is a connected and acyclic hypergraph.We investigate the supertrees with the extremal spectral radii among several kinds of r-uniform supertrees.First,by using the matching polynomials of supertrees,a new and useful grafting operation is proposed for comparing the spectral radii of supertrees,and its applications are shown to obtain the supertrees with the extremal spectral radi among some kinds of r-uniform supertrees.Second,the supertree with the third smallest spectral radius among the r-uniform supertrees is deduced.Third,among the r-uniform supertrees with a given maximum degree,the supertree with the smallest spectral radius is derived.At last,among the r-uniform starlike supert rees,the supertrees with the smallest and the largest spectral radii are characterized.