Lower bound for the Poisson bracket invariant on surfaces

Recently, L. Buhovsky, A. Logunov and S. Tanny proved the (strong) Poisson bracket conjecture by Leonid Polterovich in dimension 2. In this note, instead of open cover constituted of displaceable sets in their work, considering open cover constituted of topological discs we give a sufficient and necessary condition that Poisson bracket invariants of these covers are positive.Comment: 10 page

Local Descriptors Optimized for Average Precision

Extraction of local feature descriptors is a vital stage in the solution pipelines for numerous computer vision tasks. Learning-based approaches improve performance in certain tasks, but still cannot replace handcrafted features in general. In this paper, we improve the learning of local feature descriptors by optimizing the performance of descriptor matching, which is a common stage that follows descriptor extraction in local feature based pipelines, and can be formulated as nearest neighbor retrieval. Specifically, we directly optimize a ranking-based retrieval performance metric, Average Precision, using deep neural networks. This general-purpose solution can also be viewed as a listwise learning to rank approach, which is advantageous compared to recent local ranking approaches. On standard benchmarks, descriptors learned with our formulation achieve state-of-the-art results in patch verification, patch retrieval, and image matching.Comment: 13 pages, 8 figures. IEEE Conference on Computer Vision and Pattern Recognition (CVPR), 201

Integrating Connectivity Conservation Factors Into Legal Frameworks of China

National legislation has been recognized as a valid and effective tool for connectivity conservation worldwide. However, the existing policy and law in China is not sufficient to meet the increasing challenges of connectivity conservation. Only a few regulations focus on fundamental principles rather than any substantive result, these are related to issues including without consideration of connectivity conservation in land-use plans, ambiguity of responsibility and accountability of design entity and management authority, lack of corresponding design criteria and operating guidelines. China needs to strengthen and integrate connectivity conservation factors into legal frameworks, which relate to plan content, the rights and responsibilities of all parties, and the process of environmental impact statement preparation

What kind of research topics emerged in the biomedical domain?: A perspective from newly added subject terms in a thesaurus

Understanding what kind of research topics will emerge in scientific domains has implications for researchers, policy makers, and industry. Existing studies on emerging topics generally approach the problem from the publication perspective, that is, to retrieve a set of publications and identify emerging topics from them. This study aims to offer a different perspective to understand emerging topics. By tracing the newly added subject terms in a thesaurus, this study provides insights into what kind of topics emerged and what did not. This study found that economic, biomedical, or social impact is important for a biomedical topic to emerge in addition to the common features used for identifying emerging topics. More attention was paid to topics that have direct impact on humans than on other species. This aspect is largely neglected in the literature. The findings from this study have implications for designing predictors for emerging research topics in the biomedical domain

Numerical Investigations of Flow and Film Cooling with Endwall Contouring and Blade Tip Ejection under Rotating Turbine Conditions

An effort is made to numerically study the impact of rotating turbine conditions on the aerodynamic performance, film cooling effectiveness and heat transfer with the application of the endwall contouring and blade tip ejection. For this purpose, the three-stage HP turbine research facility at the Turbomachinery Performance and Flow Research Laboratory (TPFL), Texas A&M University, was newly designed and equipped. Using the geometry of this three-stage research turbine rig, comprehensive numerical simulations are performed to systematically study the impact of the rotation from the perspectives of both aerodynamics and heat transfer. Introducing endwall contouring has become a promising means to reduce the secondary flow losses. Thus TPFL developed a physics-based method which enables researchers and engineers to design endwall contours for any arbitrary blade types regardless of the blade loading, degree of reaction, stage load and flow coefficients. Using this approach, TPFL designed the new endwall contouring which was implemented on the platform of both the first-stage and second-stage rotors. The rotation impacts on the aerodynamics performance due to the endwall contouring were numerically studied using four different rotational speeds namely, 2000 rpm, 2400 rpm, 2600 rpm and 3000 rpm. Meanwhile, the influence on film cooling effectiveness and heat transfer caused by the endwall contouring was investigated for the first-stage rotor. Different purge-to-mainstream mass flow ratios of MFR = 0.5%, 1.0% and 1.5% were taken into account at the design rotational speed of 3000rpm. The effect of rotational speed (2400rpm, 2550rpm and 3000rpm) was investigated at typical MFR=1.0%. To investigate the flow characteristics and film cooling at high pressure turbine blade tips, four different rotor-blade tip configurations are designed and studied at TPFL: the plane and squealer tips with tip hole cooling and the plane and squealer tips with pressure-side-edge compound angle hole cooling. Seven perpendicular holes that are evenly distributed along the camber line are used for the tip hole cooling, whilst eight compound-angle holes for the pressure-side-edge cooling. The coolant was ejected through the cooling holes with low, medium and high global blowing ratios at 3000 rpm to study the impact of the blowing ratio on both the cooling effectiveness and heat transfer. Effects of rotation on the cooling effectiveness and heat transfer were calculated at the rotational speeds of 2000rpm, 2550 rpm, and 3000 rpm

Analyzing query reformulation data using multi-level modeling

This study explores the adoption of multi-level modeling to analyze query reformulation data. Thus far, the dependency among query reformulations within the same search session has not been adequately treated in the experimental design. This has limited the analysis of users’ query behavior. This study introduces multi-level modeling to query reformulation data analysis. Multi-level modeling is capable of handling the correlations among query reformulations and provides an avenue to analyzing the nested data structure. A demonstration of fitting query reformulation data to two types of multi-level models is provided. The method introduced in this study provides a potential solution to the analysis of query reformulations