SOUTH EAST ASIAN (SEA) GAMES BIOMECHANICS PROJECT

Introduction: The 19th SEA Games were held in Jakarta, Indonesia in October 1997 and presented an ideal opportunity for much needed kinematic data to be collected from the track and field athletes representing the ten South East Asian countries. The quantitative data obtained from high speed video cameras will be used to provide coaches and athletes with information to further improve their performance. Methods: Two- and three-dimensional video data was collected at 50 and 200 frames/sec using two Peak Motus motion analysis systems. The men’s javelin, hammer throw and discus events were recorded using a fixed 3-camera system, while the women’s and men’s 100 m sprints, 110 m hurdles and triple jump events were recorded using a two camera pan and tilt system. As an example of the data collected, the men’s hammer throw gold medalist was analyzed. The three cameras were placed to provide a rear, lateral and left-frontal view, with the reference origin being the center of the throwing circle: X (anterior-posterior), Y (medio-lateral), Z (vertical). The position of the hammer, resultant velocity and angle of projection (with respect to the horizontal) were measured at the instant of release. Results: The hammer was thrown distances ranging from 53.22m to 58.00m by the gold medalist. At the point of release the position of the hammer ranged from 0.75-0.88 m (X), -2.02-(-1.58) m (Y) and 1.62-1.90 m (Z), with a resultant velocity of 23.3-24.3 m/s and an angle of projection of 41.0-44.2 degrees. Conclusions: The major difference observed when comparing the SEA Games gold medalist with world class throwers was the lower release velocity of the SEA Games athletes. As a practical research project the major problem encountered were obtaining access to the field for video recording, transport of equipment, ensuring stable power supply and equipment failure

Study on Semantic Contrast Evaluation Based on Vector and Raster Data Patch Generalization

We used buffer superposition, Delaunay triangulation skeleton line, and other methods to achieve the aggregation and amalgamation of the vector data, adopted the method of combining mathematical morphology and cellular automata to achieve the patch generalization of the raster data, and selected the two evaluation elements (namely, semantic consistency and semantic completeness) from the semantic perspective to conduct the contrast evaluation study on the generalization results from the two levels, respectively, namely, land type and map. The study results show that: (1) before and after the generalization, it is easier for the vector data to guarantee the area balance of the patch; the raster data’s aggregation of the small patch is more obvious. (2) Analyzing from the scale of the land type, most of the land use types of the two kinds of generalization result’s semantic consistency is above 0.6; the semantic completeness of all types of land use in raster data is relatively low. (3) Analyzing from the scale of map, the semantic consistency of the generalization results for the two kinds of data is close to 1, while, in the aspect of semantic completeness, the land type deletion situation of the raster data generalization result is more serious

Tensor product representation of topological ordered phase: necessary symmetry conditions

The tensor product representation of quantum states leads to a promising variational approach to study quantum phase and quantum phase transitions, especially topological ordered phases which are impossible to handle with conventional methods due to their long range entanglement. However, an important issue arises when we use tensor product states (TPS) as variational states to find the ground state of a Hamiltonian: can arbitrary variations in the tensors that represent ground state of a Hamiltonian be induced by local perturbations to the Hamiltonian? Starting from a tensor product state which is the exact ground state of a Hamiltonian with $\mathbb{Z}_2$ topological order, we show that, surprisingly, not all variations of the tensors correspond to the variation of the ground state caused by local perturbations of the Hamiltonian. Even in the absence of any symmetry requirement of the perturbed Hamiltonian, one necessary condition for the variations of the tensors to be physical is that they respect certain $\mathbb{Z}_2$ symmetry. We support this claim by calculating explicitly the change in topological entanglement entropy with different variations in the tensors. This finding will provide important guidance to numerical variational study of topological phase and phase transitions. It is also a crucial step in using TPS to study universal properties of a quantum phase and its topological order.Comment: 10 pages, 6 figure

A Multitarget Land Use Change Simulation Model Based on Cellular Automata and Its Application

Based on the analysis of the existing land use change simulation model, combined with macroland use change driving factors and microlocal land use competition, and through the application of Python language integrated technical approaches such as CA, GIS, AHP, and Markov, a multitarget land use change simulation model based on cellular automata(CA) is established. This model was applied to conduct scenario simulation of land use/cover change of the Jinzhou New District, based on 1:10000 map scale land use, planning, topography, statistics, and other data collected in the year of 1988, 2003, and 2012. The simulation results indicate the following: (1) this model can simulate the mutual transformation of multiple land use types in a relatively satisfactory way; it takes land use system as a whole and simultaneously takes the land use demand in the macrolevel and the land use suitability in the local scale into account; and (2) the simulation accuracy of the model reaches 72%, presenting higher creditability. The model is capable of providing auxiliary decision-making support for coastal regions with the analysis of the land use change driving mechanism, prediction of land use change tendencies, and establishment of land resource sustainable utilization policies

Influence maximization in multilayer networks based on adaptive coupling degree

Influence Maximization(IM) aims to identify highly influential nodes to maximize influence spread in a network. Previous research on the IM problem has mainly concentrated on single-layer networks, disregarding the comprehension of the coupling structure that is inherent in multilayer networks. To solve the IM problem in multilayer networks, we first propose an independent cascade model (MIC) in a multilayer network where propagation occurs simultaneously across different layers. Consequently, a heuristic algorithm, i.e., Adaptive Coupling Degree (ACD), which selects seed nodes with high spread influence and a low degree of overlap of influence, is proposed to identify seed nodes for IM in a multilayer network. By conducting experiments based on MIC, we have demonstrated that our proposed method is superior to the baselines in terms of influence spread and time cost in 6 synthetic and 4 real-world multilayer networks

Quantum codes give counterexamples to the unique pre-image conjecture of the N-representability problem

It is well known that the ground state energy of many-particle Hamiltonians involving only 2-body interactions can be obtained using constrained optimizations over density matrices which arise from reducing an N-particle state. While determining which 2-particle density matrices are "N- representable" is a computationally hard problem, all known extreme N-representable 2-particle reduced density matrices arise from a unique N-particle pre-image, satisfying a conjecture established in 1972. We present explicit counterexamples to this conjecture through giving Hamiltonians with 2-body interactions which have degenerate ground states that cannot be distinguished by any 2-body operator. We relate the existence of such counterexamples to quantum error correction codes and topologically ordered spin systems.Comment: 4 pages, 1 figur

Anisotropic Energy Gaps of Iron-based Superconductivity from Intra-band Quasiparticle Interference in LiFeAs

If strong electron-electron interactions between neighboring Fe atoms mediate the Cooper pairing in iron-pnictide superconductors, then specific and distinct anisotropic superconducting energy gaps \Delta_i(k) should appear on the different electronic bands i. Here we introduce intra-band Bogoliubov quasiparticle scattering interference (QPI) techniques for determination of \Delta_i(k) in such materials, focusing on LiFeAs. We identify the three hole-like bands assigned previously as \gamma, \alpha_2 and \alpha_1, and we determine the anisotropy, magnitude and relative orientations of their \Delta_i(k). These measurements will advance quantitative theoretical analysis of the mechanism of Cooper pairing in iron-based superconductivity