Experimental study on the interrelation of multiple mechanical parameters in overburden rock caving process during coal mining in longwall panel

In order to comprehend the dynamic disaster mechanism induced by overburden rock caving during the advancement of a coal mining face, a physical simulation model is constructed basing on the geological condition of the 21221 mining face at Qianqiu coal mine in Henan Province, China. This study established, a comprehensive monitoring system to investigate the interrelations and evolutionary characteristics among multiple mechanical parameters, including mining-induced stress, displacement, temperature, and acoustic emission events during overburden rock caving. It is suggested that, despite the uniformity of the overburden rock caving interval, the main characteristic of overburden rock lies in its uneven caving strength. The mining-induced stress exhibits a reasonable interrelation with the displacement, temperature, and acoustic emission events of the rock strata. With the advancement of the coal seam, the mining-induced stress undergoes four successive stages: gentle stability, gradual accumulation, high-level mutation, and a return to stability. The variations in other mechanical parameters does not synchronize with the signifcant changes in mining-induced stress. Before the collapse of overburden rock occurs, rock strata temperature increment decreases and the acoustic emission ringing counts surges with the increase of rock strata displacement and mining-induced stress. Therefore, the collaborative characteristics of mining-induced stress, displacement, temperature, and acoustic emission ringing counts can be identifed as the precursor information or overburden rock caving. These results are in good consistent with on-site situation in the coal mine.

Interrelation among several important links in seismic risk analysis

In order to further reveal the interrelation among division of seismic statistical regions, delimitation of potential seismic sources and estimation of seismicity parameters, we select 21 representative sites located in different places within the range of 100°-120°E, 29°-42°N to study the influences of seismicity parameter uncertainties of statistical regions on seismic risk estimations of these sites in the inhomogeneous and homogeneous distribution models. Combining the results from this study and previous ones, we can see that different schemes for dividing seismic statistical regions can change the seismic data in a statistical region. The uncertain data and additional uncertainty in selecting time intervals for seismic statistics will result in uncertainty of seismicity parameters estimation in a statistical region. For the homogeneous model, the larger the variation of this uncertainty is, the greater the uncertain influence on the seismic risk estimation of a site will be, which means that the division of seismic statistical regions makes a major contribution. In a seismic statistical region, the delimitation of potential sources and variant weight assignment of spatial distribution functions can raise the estimated values of ground motion parameters in the place where great earthquake might occur and its vicinity. In these places, the influence of uncertainty in potential source delimitation is very obvious, especially on the absolute magnitude of ground motion parameters （e.g., intensity）, which means that the link of potential source delimitation makes a major effect. Generally speaking, the link of potential source delimitation affects mainly the sites located in the potential sources with the highest and second-high upper-limit earthquake magnitudes or in the vicinity of those with the highest upper-limit magnitude. While for the sites located in the potential sources with low upper-imit magnitudes, the uncertainty influence of statistical region division is larger than that of potential source delimitation.

Grey Interrelation Analysis for the Use of Rare Earths and the Elements in Soil in Growing Cotton

The method of grey interrelation analysis is adopted for the analysis of the relationship between the amount of rare earths applied and the factors of the soil in increasing cotton production in Kazuo County, Liaoning Province. The results show that there is an intimate relation between the use of the RE and the elements in the soil. The pH value, total K, and total P are the main factors influencing the relation, and the total N, hydrolytable N, organic matter, K2O and P2O5 are the secondary factors. This provides a scientific basis for the use of the RE.

Fan‐hinged shear instead of frictional stick–slip as the main and most dangerous mechanism of natural,induced,and volcanic earthquakes in the earth's crust

Frictional stick–slip instability along pre‐existing faults has been accepted as the main mechanism of earthquakes for about 60 years,since it is believed that fracture of intact rocks cannot reflect such features inherent in earthquakes as low shear stresses activating instability,low stress drop,repetitive dynamic instability,and connection with pre‐existing faults.This paper demonstrates that all these features can be induced by a recently discovered shear rupture mechanism(fan‐hinged),which creates dynamic ruptures in intact rocks under stress conditions corresponding to seismogenic depths.The key element of this mechanism is the fan‐shaped structure of the head of extreme ruptures,which is formed as a result of an intense tensile cracking process,with the creation of inter‐crack slabs that act as hinges between the shearing rupture faces.The preference of the fan mechanism over the stick–slip mechanism is clear due to the extraordinary properties of the fan structure,which include the ability to generate new faults in intact dry rocks even at shear stresses that are an order of magnitude lower than the frictional strength;to provide shear resistance close to zero and abnormally large energy release;to cause a low stress drop;to use a new physics of energy supply to the rupture tip,providing supersonic rupture velocity;and to provide a previously unknown interrelation between earthquakes and volcanoes.All these properties make the fan mechanism the most dangerous rupture mechanism at the seismogenic depths of the earth's crust,generating the vast majority of earthquakes.The detailed analysis of the fan mechanism is presented in the companion paper“New physics of supersonic ruptures”published in DUSE.Further study of this subject is a major challenge for deep underground science,earthquake and fracture mechanics,volcanoes,physics,and tribology.

试论梁启超对西方近代地理学在中国传播的贡献

阐述在清末民初西风东渐日益强劲的背景下,维新派的代表人物梁启超在推介西方近代地理学关于人地关系、地理环境决定论等方面的贡献和影响,同时指出梁启超也是最早正确评价徐霞客其人其事的一位学者。这都是中国地理学史上的大事,但为已有的中国地理学史所不载,应对梁启超的以上贡献给予充分肯定和公正评价。

Profile, spectrum and significance of hepatitisB virus genotypes in chronic HBV-infected patients in Yunnan, China

BACKGROUND: There are significant variations in the geographical distribution of hepatitis B virus (HBV) genotypes throughout the world, and some genotypes are associated with different clinical outcomes. Eight genotypes of human HBV (designated A-H) have been reported. The present study was designed to examine the distribution of HBV genotypes among patients at various stages of chronic type B liver disease in Yunnan Province, China, and to explore its significance and the relationship of HBV genotype with gender and age, clinical spectrum of chronic HBV infection, and viral replicative activity. METHODS: Serum samples from 126 patients with chronic HBV infection from Yunnan Province, including 26 chronic asymptomatic HBV carriers (ASC), 61 patients with chronic hepatitis B (CHB) (21 mild, 30 moderate and 10 severe), 20 patients with chronic fulminant hepatic failure (CFHF), 12 patients with HBV-related liver cirrhosis (LC) and 7 patients with HBV-related hepatocellular carcinoma (HCC) were analyzed using reverse dot blot (RDB) methodology, which is based on the reverse hybridization principle for HBV genotyping. The relations of HBV genotype with gender and age, clinical patterns, and serological data of the patients were analyzed. RESULTS: In this series, genotypes A, B, C, and D were found. 38.1% patients (48/126) belonged to B, 54.8% (69/126) to C, 0.8% (1/126) to D, 1.6% (2/126) to a mixture of B and C, and 1.6% (2/126) to a mixture of A and C. 3.2% patients (4/126) had unknown genotypes. No other genotypes (E, F, G, and H) were found. Genotypes B and C were predominant. There was a statistically significant difference in the distributions of genotypes C and B (chi(2)=7.04, P=0.008), and C was the dominant genotype in all patient categories. The rate of genotype B in the mild CHB group was significantly higher than that in the moderate and severe groups (chi(2)=12.16, P=0.0001; chi(2)=11.98, P=0.001, respectively), the ASC group (chi(2)=5.46, P=0.02), the CFHF group (chi(2)=5.53, P=0.019), and the LC/HCC group (chi(2)=12.13, P=0.001). The rate of genotype C in the LC/HCC group and the severe CHB group were significantly higher than that in the mild group (chi(2)=9.95, P=0.002; chi(2)=8.78, P=0.003, respectively). HBV DNA positivity and HBeAg positivity were higher in genotype C than in genotype B (chi(2)=9.81, P=0.002; chi(2)=3.85, P=0.05, respectively). The prevalence of genotype C showed an increasing trend in lowest-, middle- and highest-level groups of HBV replication (25.0%, 70.0%, and 55.6%, respectively); in contrast, the prevalence of genotype B showed an opposite trend in the same order (62.5%, 30.0%, and 37.0%, respectively). The rate of genotype C in the highest-level group of HBV replication was higher than genotype B (chi(2)=7.45, P=0.006). The rate of genotype C in the over-30 age group was higher than that in the below-30 age group (chi(2)=3.7, P=0.05). There was no difference between the sexes (P>0.05). More severe liver damage was found in genotype C than in genotype B (P<0.05). CONCLUSIONS: The predominant HBV genotypes in chronic HBV-infected patients are B and C, and C is the most prevalent genotype in Yunnan Province, China. HBV genotype C is associated with the development of more severe liver disease and a higher level of HBV viral replication, and genotype B has a relatively good progress.

Dynamic Variation and Correlation of Pericarp Tenderness and Component Contents of Super Sweet Corn(sh_(2))in Kernel Development

Data on the mechanism of how pericarp components in fresh sweet corn affect pericarp tenderness are scarce.This study explored variation and correlation of pericarp tenderness and components over time in three inbred lines of sweet corn that were selected for their differences in pericarp tenderness.The three lines presented a curvilinear increase in pericarp tenderness(puncture reading)from 12 to 24 d after pollination(DAP)across two environments,with the means at each time point always in the same order:S33205>T105>PE10.Pericarp tenderness difference at each same time point in two environments over time varied similarly in each of the three inbred lines:increasing first,then dropping after peak,and insignificant at the end.Of the main pericarp components,mean contents were in the order:hemicellulose>cellulose>lignin in both environments at each time point for the three inbred lines.As the pericarp developed,hemicellulose content increased gradually,lignin content varied along a single-peak curve,cellulose content fluctuated around 24%,and pectin and ash contents changed slightly and irregularly.The pericarp of PE10,with the most tender pericarp,accumulated hemicellulose faster than other two lines.Hemicellulose and lignin contents were significantly correlated with pericarp tenderness,and the main components affected pericarp tenderness.

Dreaming Forward: Postidentity and the Generative Thresholds of Tourism

This manuscript from Hollinshead and Vellah calls for researchers in Tourism Studies and related Fields to reflect upon their own role in refreshing the social imaginaries of“after-colonialism”under the nomadisms of our time.Deleuzian in outlook,it positions the“post”of postcolonialism not as an end to colonialism’s imperatives but as a generative-portal through which new-seeds-of-”becoming”are discernable as the postidentities(rather than the“identities”)of populations are interpretable in multidirectional,non-hierarchical,and not easily-predictable ways.In provoking(after Deleuze)thought per rhizomatic processes(rather than via fixed concepts),the manuscript-critiquing these dynamic matters of“postidentity”-then harnesses the insights of(Leela)Ghandi’s on hybrid-nomadic-subjects,and of Venn on alternative-(com)possible-futures.Thereafter,these concerns of and about“after-colonialism”are critically contextualised within Aboriginal“Australia”,via the views of a pool of Indigenous intellectuals there,who synthesise the disruptive dialectics of belonging-cum-aspiration which they maintain that they and fellow Aboriginal people(of many sorts)face today.Throughout this manuscript,the agency and authority of tourism hovers in its sometimes-manifest/sometimes-latent generative power to project empowering postidentities for the world’s“host”or“visited”populations today.

The Analysis of Systems of Measurement for the Construction of Geometrical Models of the Product

In the present work,the relevant components of the two basic system of measurement are defined through the analysis of existing systems of measurement for geometrical modeling.The major features of such systems related to the ways of formation of the two-dimensional complex drawing of a geometrical image on the basis of laws of projective connections are revealed.Interrelations of the elements of different systems of measurement with various projections of a geometrical image are defined.The relative location of projections of a geometrical image into the constructed two-dimensional complex drawings for various systems of measurement is discussed.The rationale behind a particular arrangement of views in the projective drawing of a product in the analyzed systems of measurement is explained.

Competitive analysis of online inventory problem with interrelated prices

This paper investigates the online inventory problem with interrelated prices in which a decision of when and how much to replenish must be made in an online fashion even without concrete knowledge of future prices. Four new online models with different price corre- lations are proposed in this paper, which are the linear-decrease model, the log-decrease model, the logarithmic model and the exponential model. For the first two models, the online algo- rithms are developed, and as the performance measure of online algorithm, the upper and lower bounds of competitive ratios of the algorithms are derived respectively. For the exponential and logarithmic models, the online algorithms are proposed by the solution of linear programming and the corresponding competitive ratios are analyzed, respectively. Additionally, the algorithm designed for the exponential model is optimal, and the algorithm for the logarithmic model is optimal only under some certain conditions. Moreover, some numerical examples illustrate that the algorithms based on the dprice-conservative strategy are more suitable when the purchase price fluctuates relatively flat.

Generalized Algorithms of Discrete Optimization and Their Power Engineering Applications

Generalized algorithms for solving problems of discrete, integer, and Boolean programming are discussed. These algorithms are associated with the method of normalized functions and are based on a combination of formal and heuristic procedures. This allows one to obtain quasi-optimal solutions after a small number of steps, overcoming the NP-completeness of discrete optimization problems. Questions of constructing so-called “duplicate” algorithms are considered to improve the quality of discrete problem solutions. An approach to solving discrete problems with fuzzy coefficients in objective functions and constraints on the basis of modifying the generalized algorithms is considered. Questions of applying the generalized algorithms to solve multicriteria discrete problems are also discussed. The results of the paper are of a universal character and can be applied to the design, planning, operation, and control of systems and processes of different purposes. The results of the paper are already being used to solve power engineering problems.

MODALS RELATED TO STABILITY AND COMFORTABILITY OF ARTICULATED VEHICLE

An articulated vehicle is simplified as a multibody system. tires are simplified asparagraphic linear springs with damping, and the differential equations of system motion aregiven. Taking the ZL10 loader as an example, and measuring three-dimensional dynamicstiffness and damping of the tires, seven orders of natural frequencies and related natural modesare obtained by modal analysis, and shown on the computer with three-dimensional moving pic-tures. The following conclusions are obtained: the first order frequency relates to the horizontalstability, the second order frequency relates to the vertical stability, and each order of frequencyrelates to the comfortability. All results of this work can be applied .to monitor stability and eval-uate comfortability.