Search

In this paper, we study the weak convergence and convergence rate in the weak law of large numbers for weighted sums of a class of random variables satisfying the Rosenthal type inequality. The necessary and sufficient conditions for the convergence rates in the weak law of large numbers under some mild conditions are provided. Moreover, the main results that we established are applied to simple linear errors-in-variables regression models and nonparametric regression models based on a class of random errors. Finally, we present some numerical simulations to assess the finite sample performance of the theoretical results. [ABSTRACT FROM AUTHOR]

Image segmentation implementation provides simplified and effective feature information of image. Neural network algorithms have made significant progress in the application of image segmentation task. However, few studies focus on the implementation of hardware circuits with high-efficiency analog calculations and parallel operations for image segmentation problem. In this paper, a memristor-based competitive Hopfield neural network circuit is proposed to deal with the image segmentation problem. In this circuit, the memristive cross array is applied to store synaptic weights and perform matrix operations. The competition module based on the Winner-take-all mechanism is composed of the competition neurons and the competition control circuit, which simplifies the energy function of the Hopfield neural network and realizes the output function. Operational amplifiers and ABM modules are used to integrate operations and process external input information, respectively. Based on these designs, the circuit can automatically implement iteration and update of data. A series of PSPICE simulations are designed to verify the image segmentation capability of this circuit. Comparative experimental results and analysis show that this circuit has effective improvements both in processing speed and segmentation accuracy compared with other methods. Moreover, the proposed circuit shows good robustness to noise and memristive variation. [ABSTRACT FROM AUTHOR]

In order to study the turnabout roller coal slime freezing adhesion problem in the process of open-pit mine during winter,experimental apparatus was designed by ourselves,simulated the production site,studied the change of freezing adhesive characteristics of different material in different temperature and different freezing time condition. The results show that different materials and dry basis moisture content 40% of the coal slime have different freezing adhesive strength,among them PTFE material in normal and tangential freezing adhesive strength is lower than other materials,2. 5hours at- 25℃,normal freezing adhesive coefficient is 0. 037 MPa,tangential freezing adhesive coefficient is 0. 076 MPa,it is about 1 /3 of UHMW-PE material ’s normal freezing adhesive coefficient,and about 1 /6 of it’s tangential freezing adhesive coefficient; it is about 1 /44 of Q235 material’s normal freezing adhesive coefficient,and about 1 /19 of it’s tangential freezing adhesive coefficient,It illustrates PTFE has good antifreezing adhesive ability. Tests also show that temperature of freezing adhesive strength has a certain influence,but is not a linear relation; After 3 hours freezing adhesive strength change is small; Material of tangential freezing adhesive coefficient is usually larger than normal freezing adhesive coefficient; Surface freezing adhesive strength is independent of how much coal sample.

Coal is the important basic energy in China,while the coal freezing adhesion seriously restricts with coal mine safe and efficient production in winter. Pressure as a secondary factor of coal freeze condition,it has an important influence on coal freezing adhesive strength. Through the freezing adhesive strength test device designed by ourselves,under conditions of- 25 ℃temperature and 3h freezing time,freezing adhesive characteristic of six different materials with moisture content 40% of the coal slime were tested. Studies have shown that pressure usually makes the coal freezing adhesive strength increase,such as Q235,normal freezing adhesive strength of under prepressure is 6. 2 times bigger than under no pressure’s,tangential freezing adhesive strength of under prepressure is 5. 9 times bigger than under no pressure’s. But only PTFE’s normal and tangential freezing adhesive strength under the condition of pressure both do not increase among six materials. In a sense,pressure will increase the hydrophilic material freezing adhesive strength,instead it will reduce the hydrophobic material freezing adhesive strength. The excellent characteristic of PTFE material shows wide application prospect in cold area of coal transportation,it deserves further study.

Coal is the important basic energy in China,however due to the problems of conveyor belt running deviation and avultion caused by freezing adhesive turnabout roller surface,it seriously restricts with coal mine safe and efficient production in cold regions during winter and brings huge economic losses to the company,although existing solutions have a certain ease of coal freezing adhesion but can not fundamentally solve the problem. Through the freezing adhesive strength test device designed by ourselves,under conditions of- 25℃ temperature and 3h freezing time,freezing adhesive characteristic of four different materials with moisture content 40% of the coal slime were tested. Experimental studies have found that with the decrease of material waterlubricating coefficient of kinetic friction coal normal and tangential freezing adhesive strength decrease,it shows a certain linear relation,the results indicate that improving the water-lubricating performance can reduce the freezing adhesive strength,the discovery has important guiding significance to the selection and preparation of anti-freezing adhesive coating in engineering field,it deserves further explore and study.

According to the freezing adhesion problem which exists between the coal and the belt conveyor turnabout roller surface,the freezing adhesive strength test device is created. To simulate the belt conveyor turnabout roller surface environment,- 30℃ temperature and 3h freezing time of stress conditions,several different materials are studied with moisture content 30% of the coal slime,each of the freezing adhesive characteristic. Comparative tests have proved that UHMW-PE material in normal,tangential freezing adhesive strength is lower than test of other materials,which proves that it is provided with good anti-freezing adhesive capability. According to UHMW-PE package roller based on the actual application situation can further illustrate that the UHMW-PE can be used as roller coating in order to achieve anti-freezing adhesive effect.

In order to optimize the layout of the large vibrating screen side panel stiffeners,Topology optimization design was applied in structural design of the side panel stiffeners. The topology optimization model of side panel stiffeners which were based on the goal of maximizing the lateral stiffness of side panel stiffeners was established. According to the pseudo density distribution of the topology optimization,the stiffeners would be rewired. The modal analysis and the harmonic response analysis were done for the panels before and after optimization. Compared with the original side panel structure,the new side panel’s dynamic stress was reduced by 56. 5%,Vibration displacement was reduced by 55. 3%. In addition,the first natural frequency was improved by 72. 03%,the natural frequency was far from working frequency effectively.

The finite element model of belt conveyor drum is established.And the stress and deformation of with and without reinforcement ring and different structures of reinforcing ring are analyzed by using finite element analysis software ANSYS.The corresponding relation between the different structures of reinforcing ring and the maximum deformation of drive drum is obtained after modeling and calculation.And the function relation between different structures of reinforcing ring and maximum displacement is fitted by using MATLAB,and the structure of reinforcing ring with minimum displacement can be selected according to the function.The theoretical basis and thought are provided for the standardized design of reinforcing ring of belt conveyor drive drum.