Enhanced Gradient-Based Local Feature Descriptors by Saliency Map for Egocentric Action Recognition

Egocentric video analysis is an important tool in healthcare that serves a variety of purposes, such as memory aid systems and physical rehabilitation, and feature extraction is an indispensable process for such analysis. Local feature descriptors have been widely applied due to their simple implementation and reasonable efficiency and performance in applications. This paper proposes an enhanced spatial and temporal local feature descriptor extraction method to boost the performance of action classification. The approach allows local feature descriptors to take advantage of saliency maps, which provide insights into visual attention. The effectiveness of the proposed method was validated and evaluated by a comparative study, whose results demonstrated an improved accuracy of around 2%

A method to evaluate the overall breakage degree of pre-weakening processing and its applications

The product fineness indicator t and the pre-weakening degree indicator percentage change of A * b value (C) were used to described the two aspects of the breakage result of processing with pre-weakening effect. However, there lacks a method to evaluate the ‘overall’ breakage degree with a single index. It was observed that when the high voltage pulse breakage (HVP breakage or HVPB) induced cracks inside pre-weakened particles were consumed during impact breakage, the breakage characteristics of the progeny particles are the same to raw ore particles. Based on this phenomenon, the concepts of equivalent size S and equivalent size reduction t are proposed. Raw ore particles of size S is ‘equivalent’ to pre-weakened particles of size S in terms of their impact breakage product size distribution. Therefore the value of S and the consequently derived t can be used to evaluate the overall breakage degree of pre-weakened particles. The calculation procedure of S and t is demonstrated in the context of HVP breakage. It is found that the impact breakage product of pre-weakened particles can be well predicted from S. In addition to the evaluation of overall breakage degree of pre-weakening processing, this method also has potential to apply in the simulation of comminution circuits with pre-weakening processing and the development of breakage model for processing with pre-weakening effect

Effect of feed quantity on breakage degree of ore particles subjected to high voltage pulses

The effect of spatial arrangement of feed sample on the breakage degree of high voltage pulse breakage (HVPB) product was investigated by varying the number of feed particles discharged simultaneously inside a processing vessel. Two kinds of hard porphyry copper ores were treated using the commercial HVPB tester SELFRAG Lab and a custom-made unit respectively. The results indicate that, at given electrode gap and specific energy, the fineness (t10) of HVPB product increases with feed quantity, while the pre-weakening degree (CAb) of HVPB product decreases with feed quantity. A new index of equivalent product fineness (t10e), which reflects the combined effect of\ua0t10\ua0and\ua0CAb, is employed to represent the overall breakage degree of HVPB product. It is found that the value of\ua0t10e\ua0has a positive relation with the feed quantity of HVPB tests. The effect of feed quantity on ore behaviour in HVPB is attributed to the influence of particles bed volume on breakdown strength and the negative effect of water gap between ore particles and top electrode. Finally, it is recommended to take feed quantity into consideration in HVPB studies to obtain comparative testing results, and to select the most appropriate breakage degree indexes from\ua0t10,\ua0CAb\ua0and\ua0t10e\ua0according to research aim. Particularly, electrode gap just filled by feed particles is preferred to optimize the over breakage degree of ore particles