Improving Efficiency in Deep Learning for Large Scale Visual Recognition

The emerging recent large scale visual recognition methods, and in particular the deep Convolutional Neural Networks (CNN), are promising to revolutionize many computer vision based artificial intelligent applications, such as autonomous driving and online image retrieval systems. One of the main challenges in large scale visual recognition is the complexity of the corresponding algorithms. This is further exacerbated by the fact that in most real-world scenarios they need to run in real time and on platforms that have limited computational resources. This dissertation focuses on improving the efficiency of such large scale visual recognition algorithms from several perspectives. First, to reduce the complexity of large scale classification to sub-linear with the number of classes, a probabilistic label tree framework is proposed. A test sample is classified by traversing the label tree from the root node. Each node in the tree is associated with a probabilistic estimation of all the labels. The tree is learned recursively with iterative maximum likelihood optimization. Comparing to the hard label partition proposed previously, the probabilistic framework performs classification more accurately with similar efficiency. Second, we explore the redundancy of parameters in Convolutional Neural Networks (CNN) and employ sparse decomposition to significantly reduce both the amount of parameters and computational complexity. Both inter-channel and inner-channel redundancy is exploit to achieve more than 90\% sparsity with approximately 1\% drop of classification accuracy. We also propose a CPU based efficient sparse matrix multiplication algorithm to reduce the actual running time of CNN models with sparse convolutional kernels. Third, we propose a multi-stage framework based on CNN to achieve better efficiency than a single traditional CNN model. With a combination of cascade model and the label tree framework, the proposed method divides the input images in both the image space and the label space, and processes each image with CNN models that are most suitable and efficient. The average complexity of the framework is significantly reduced, while the overall accuracy remains the same as in the single complex model

An experimental study of the natural characteristics of the wheeled and the tracked self-propelled guns

With wheeled and tracked self-propelled guns as research object, the study carries out the experimental modal analysis by using traditional method of hammering and operational modal analysis method, and obtains low-order natural frequency of the guns, and thus lays the foundation for further research on the vibration characteristics of wheeled and tracked self-propelled guns. By contrasting the low-order natural characteristics of wheeled and tracked self-propelled guns, conclusions can draw as the following: the modal shapes (from low to high) of wheeled and tracked self-propelled guns are pitch, translation and roll; when the modal shapes are identical, the natural frequency of tracked self-propelled guns is greater than that of wheeled self-propelled guns, which accords with the test results of the gun’s suspension equivalent stiffness; for wheeled self-propelled guns, an accurate measure of the gun’s natural characteristics is feasible by either the traditional or the operational modal analysis method. When it comes to tracked self-propelled guns, the operational modal analysis method is more accurate

Experimental research on influence of ground vibration on gun measurement instrument support

In order to know well the vibration law on influence of ground vibration on instrument support in gun firing process, a measuring method for the vibration response of the instrument support based on the principle of acceleration measurement is presented. The instrument support is arranged on the ground. When the gun fires, the acceleration response of the instrument support is measured. The vibration velocity and vibration displacement responses of the support can be obtained by the integral operation of the acceleration. The results show that when the gun fires with single shot and the period of the projectile in-bore motion, the vibration response of the instrument support caused by ground vibration is very small, and it can be ignored. When the projectile moves outside the bore, the ground vibration has a significant influence on the vibration of the instrument support. The vibration response of the instrument support in the range of muzzle shock wave is mainly caused by the muzzle shock wave

Research on measuring method of the angular displacement of muzzle vibration

The angular displacement of the muzzle vibration has importance influence on the firing dispersion of gun. In order to solve the measuring problem on the angular displacement of the muzzle vibration in firing environment, a kind of measuring method of the angular displacement of the muzzle vibration based on the laser and the triangle principle was presented, and its measuring system was developed. The laser beam was sent by a laser. After the laser beam was reflected by a reflector on muzzle, the reflective beam was received by the position sensitive detector (PSD). Combining the optical distance parameter and the triangle relation, the angular displacement of the muzzle vibration could be obtained. The measuring error analysis of the system and the verification of the firing environment in shooting range were made. The performances of the measuring system were that the measuring range of the angular displacement was ±35', its angle resolution was 0.1', its relative errors under the different illumination conditions were less than 2 %. The measuring system can meet the needs of the gun measurement