Efficient Astronomical Data Condensation Using Approximate Nearest Neighbors

Extracting useful information from astronomical observations represents one of the most challenging tasks of data exploration. This is largely due to the volume of the data acquired using advanced observational tools. While other challenges typical for the class of big data problems (like data variety) are also present, the size of datasets represents the most significant obstacle in visualization and subsequent analysis. This paper studies an efficient data condensation algorithm aimed at providing its compact representation. It is based on fast nearest neighbor calculation using tree structures and parallel processing. In addition to that, the possibility of using approximate identification of neighbors, to even further improve the algorithm time performance, is also evaluated. The properties of the proposed approach, both in terms of performance and condensation quality, are experimentally assessed on astronomical datasets related to the GAIA mission. It is concluded that the introduced technique might serve as a scalable method of alleviating the problem of the dataset size.

Development of a New Contact Angle Control Algorithm for Level-Set Method

A contact angle control algorithm is developed and implemented in the multiphase interface tracking flow solver—phasta. The subgrid force model is introduced to control the evolving contact angle. The contact angle force is applied when the current contact angle deviates from the desired value (or range of values) and decreases to zero when it reaches the desired value. The single bubble departure simulation and the capillary flat plates simulation are performed for verification purpose. The numerical results are compared with the analytical solution with good agreement. The mesh resolution sensitivity analysis and parametric study are conducted for both simulations. Coupled with the other existing capabilities in phasta like evaporation and condensation algorithm, the contact angle control algorithm will allow us to investigate the boiling phenomenon in various conditions with lower cost (by utilizing localized mesh refinement for bubble growth region) compared to uniformly refined structured meshes and in engineering geometries.

Research on Fast Conversion of Large Complex Block Model in SURPAC to Three-Dimensional Numerical Grid in FLAC3D

Existing numerical grid generation based on Surpac block model is inefficient when the grid quantity is large. This article obtains from the existing methods, summarizes the complete process, and adds the key details of it. By setting simpler nodes condensation algorithm, improving the problem of low conversion efficiency caused by the too large node number, achieving the fast effective conversion of Surpac block model to FLAC3D model by using C language programming. This new method has been used in building rock burst hazard analysis model of Ling-Long gold mine, which proves this modeling method is feasible and effective.