Experimental Study on the Compaction and Deformation of Filling Gangue by Reducing Waste Gangue for Filling Mining

The coal mining technology of fully mechanized solid filling is an efficient and green mining method that integrates “sediment reduction” and “emission reduction.” However, the discharge of wasted gangue and surface subsidence are controlled by the amount of wasted gangue used in filling mining and the compaction rate of gangue filled into a goaf, respectively. To increase the consumption of wasted gangue and reduce surface subsidence, mixed gangue composed of equal-quality washed gangue and crushed gangue is proposed as a raw material for solid filling on the basis of gradation theory. Next, a screening experiment was performed to analyze the grain gradation of different specimens, and a compression experiment was executed to compare and analyze the compression characteristics. The results show that the nonuniformity coefficient of mixed gangue is 55.2 and the curvature coefficient is 1.53, which significantly improve the grain gradation of washed gangue. The degree of relative compaction of mixed gangue is 1.226, which is significantly lower than that of washed gangue, which is 1.33. The deformation modulus of mixed gangue is 23–135 MPa, which is better than that of washed gangue (26–100 MPa), indicating that the compressive resistance of mixed gangue is significantly improved. The case study of the Tangkou mine suggests that mixed gangue greatly promotes the consumption of wasted gangue and can effectively control the surface deformation.

ASSESSMENT OF A CITY CENTRALITY BASED ON CONNECTION CURVATURE COEFFICIENT

Положение города в системе «центр-периферия» во многом определяется его транспортно-географическим положением. Последнее является одной из наиболее значимых составляющих экономико-географического положения и определяет динамику социально-экономического развития города. В настоящем исследовании оценивается центральность городов некоторых регионов России на основе применения коэффициента кривизны сообщения. Такой коэффициент рассчитывается как сумма частных расстояния по дороге и напрямую между городами. Чем меньше итоговое значение коэффициента - тем более выгодное (центральное) положение занимает город по отношению к другим городам региона. Нами показано, что первый город (крупнейший по людности и, как правило, административный центр региона) обладает наименьшим (т.е. лучшим) значением показателя рассчитанного коэффициента. The position of the city in the «center-periphery» system is largely determined by its transport and geographical location. The latter is one of the most significant components of the economic and geographical position and determines the dynamics of the socio-economic development of the city. This study evaluates the centrality of cities in some regions of Russia based on the application of the connection curvature coefficient. This ratio is calculated as the sum of the private distances by road and directly between cities. The lower the final value of the coefficient, the more favorable (central) position the city occupies in relation to other cities in the region. We have shown that the first city (the largest in terms of population and, as a rule, the administrative center of the region) has the smallest (that is, the best) value of the indicator of the calculated coefficient.

The Correlation of Cycloplegic Refraction with Corneal Radius of Curvature-Adjusted Axial Length in Chinese Preschoolers

Background: In order to master the refractive status and detect severe refractive errors quickly and effectively, this study aimed to investigate the association of axial length after adjusting for corneal radius of curvature with refraction in a group of Chinese preschoolers. Methods: Retrospective review of 716 Chinese children aged from 3 to 6 years, who underwent cycloplegic optometry with 1% atropine eye gel in the ophthalmology department of Children’s Hospital of Fudan University, National Children’s Medical Center in Shanghai. Meanwhile axial length, corneal radius of curvature and cycloplegic autorefraction were obtained and axial length/corneal radius of curvature (AL/CR) ratio was calculated. The correlations of spherical equivalent refraction (SER) with axial length, corneal radius of curvature, AL/CR ratio and corneal radius of curvature-adjusted axial length were analyzed. Results: Only data from the right eye were included in this analysis. Among 716 eyes of 716 Chinese preschoolers, the mean (±SD) SER was 2.28±2.41 diopters (D), of which hyperopia, emmetropia, myopia were 84.64%, 8.54%, 6.84%, respectively. The mean(±SD) axial length, corneal radius of curvature and AL/CR ratio were 21.89±1.01mm, 7.76±0.27 mm, and 2.82±0.13, respectively. The SER was highly negative correlated with both axial length (coefficient –0.722) and AL/CR ratio (coefficient-0.814), and weakly correlated with corneal radius of curvature (coefficient 0.090) and gender(coefficient 0.093). Axial length was weakly correlated with age and gender(coefficient 0.232 and 0.268, respectively), but moderately correlated with corneal radius of curvature (coefficient 0.424). After adjusting for corneal radius of curvature, the correlation coefficient between SER and axial length significantly increased to-0.918. Conclusion: In the samples of 716 3-to 6-year-old Chinese children, axial length was moderately correlated with corneal radius of curvature. After adjusting for corneal radius of curvature, refraction was closely correlated with axial length than axial length alone and AL/CR ratio. Therefore, corneal radius of curvature-adjusted axial length might be a useful tool for pediatric ophthalmologists to detect refractive errors. Key Words: spherical equivalent refraction; corneal radius of curvature; adjusted; axial length; preschoolers.

Warsaw Glacial Quartz Sand with Different Grain-Size Characteristics and Its Shear Wave Velocity from Various Interpretation Methods of BET

After obtaining the value of shear wave velocity (VS) from the bender elements test (BET), the shear modulus of soils at small strains (Gmax) can be estimated. Shear wave velocity is an important parameter in the design of geo-structures subjected to static and dynamic loading. While bender elements are increasingly used in both academic and commercial laboratory test systems, there remains a lack of agreement when interpreting the shear wave travel time from these tests. Based on the test data of 12 Warsaw glacial quartz samples of sand, primarily two different approaches were examined for determining VS. They are both related to the observation of the source and received BE signal, namely, the first time of arrival and the peak-to-peak method. These methods were performed through visual analysis of BET data by the authors, so that subjective travel time estimates were produced. Subsequently, automated analysis methods from the GDS Bender Element Analysis Tool (BEAT) were applied. Here, three techniques in the time-domain (TD) were selected, namely, the peak-to-peak, the zero-crossing, and the cross-correlation function. Additionally, a cross-power spectrum calculation of the signals was completed, viewed as a frequency-domain (FD) method. Final comparisons between subjective observational analyses and automated interpretations of BET results showed good agreement. There is compatibility especially between the two methods: the first time of arrival and the cross-correlation, which the authors considered the best interpreting techniques for their soils. Moreover, the laboratory tests were performed on compact, medium, and well-grained sand samples with different curvature coefficient and mean grain size. Investigation of the influence of the grain-size characteristics of quartz sand on shear wave velocity demonstrated that VS is larger for higher values of the uniformity coefficient, while it is rather independent of the curvature coefficient and the mean grain size.

Wear depth calculation and influence factor analysis for groove ball bearing

Based on Hertz contact theory and load distribution, the formulas for contact stress cycle times, slip distance and wear depth measurements are derived, and the influences of load, curvature coefficient, roll body diameter and friction coefficient on the contact region wear depth and distributions are thoroughly analyzed. The results show that the wear depth is zero at the pure rolling point and the long half-axle terminals of contact ellipse, and reaches maximum value near by the long half-axle terminals of the contact ellipse, and further shows that the wear depth increases with increase of the load and friction coefficient, however decreases with increase of the curvature coefficient and roll body diameter.

TYPOLOGICAL FEATURES OF THE FRONTAL BONE SUPRAORBITAL MARGIN

The article presents data about the anatomical variability of the supraorbital edge of the frontal bone, obtained by skull craniometry of people using lepten facial index values. The evaluation of a number of indicators developed by the size of the orbit and the classification reflects the degree of curvature of the arc of the supraorbital region, based on the author's introduction curvature coefficient (CC). Three groups of skulls on the value of CC supraor-bital edge of the frontal bone: less than 30 a small curved arc; 30-45 with average and more than 45 with a large arc curved. Significant correlation of moderate intensity was found between the values of CC and the facial index.

Research on Disparity Map Generation Method of Underwater Target Based on the Improved SIFT Algorithm

In order to obtain the depth information of the underwater target, it’s necessary to generate the disparity map based on binocular vision stereo matching. In the circulation water channel, the stereo matching experiments with underwater target were carried out by using the BM algorithm, SGBM algorithms and SIFT algorithm respectively. Then the characteristics of the disparity maps were analyzed for the three kinds of stereo matching algorithms. Compared with the BM algorithm and SGBM algorithms, the SIFT algorithm has been proved to be more suitable for underwater stereo matching. In order to obtain more feature points of underwater image, it is necessary to improved SIFT algorithm parameter. Underwater image matching experiments were made to determine the principal curvature coefficientγ. The results illustrated that the improvedγis better than the original value for underwater disparity map generation.

The Statistical Analysis of Gravel Soil Permeability Coefficient of the Three Gorges Reservoir Area

According to the Geological Diversity and Soil Characteristics in the Gorges Reservoir Area, the Statistical Analysis was Carried on the Content, Grade, Porosity and Permeability Coefficient (PC) of Gravel Soil, Respectively. the Value of Saturated Permeability Coefficient (SPC) is up to 10-3. the Value of the Total SPC is that Zigui is the Highest, Badong-Fengjie Area is Less than that in Zigui, and it is the Lowest in Fengjie-Chongqing Area in its Distribution. the Relationship between the Montmorillonite (MMT) Content, Stone Content, the Uneven Coefficient and PC are all Positive. the Curvature Coefficient and Void Ratio are all Negatively Correlated with PC. these Data Showed the Relationship between the Index of Material Composition and PC of Gravel Soil.