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. F...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.展开更多
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 th...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.展开更多
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 in...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.展开更多
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...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.展开更多
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 genoty...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.展开更多
基金Supported by the National Natural Science Foundation of China(11571013,11471286)
文摘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.
基金supported by the State Key Research Development Program of China(2022YFC3004602)Independent Research fund of Joint NationalLocal Engineering Research Centre for Safe and Precise Coal Mining(Anhui University of Science and Technology)(EC2022001)+2 种基金the National Natural Science Foundation of China(41872205)Beijing Natural Science Foundation(8202041)the Fundamental Research Funds for the Central Universities(2022YJSLJ08,2022JCCXNY03).
文摘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.
文摘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.
文摘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.
文摘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.
