Mining safety and health improvements over the past decades are remarkable by many metrics, and yet the expectation of society, and the goal of the mining industry, is zero harm. If we examine the underlying enablers ...Mining safety and health improvements over the past decades are remarkable by many metrics, and yet the expectation of society, and the goal of the mining industry, is zero harm. If we examine the underlying enablers for the significant gains that have been achieved, the key role that research to help understand the causes of problems and to develop lasting solutions is clear. Many of the remaining challenges have been resistant to solutions by various approaches. Some, such as fatalities and injuries from ground control or powered haulage are prominent year after year. Different approaches are indicated and new solutions will be required if we are to achieve a goal of zero harm. These will originate with research, but into which topics, and what are some of these different approaches? This paper examines the current state of mine safety in the United States and highlights areas of significant opportunity for research that will lead to solutions. The likely direction of research that will enable realization of the ‘‘zero harm'' goal is described in terms of evolutionary and revolutionary approaches. Both are important, but the author's view is that some of the largest gains will be made with trans-disciplinary approaches that break from the past. Topical areas of research are suggested and several research questions are given to illustrate the direction of future research in mining safety and health.展开更多
The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that belong to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clini...The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that belong to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clinical treatment. In this article, a holographic interferometer has been adopted to measure the diffusivity of amino acids in non-Newtonian fluid with the use of real-time holographic interference technique. In order to prove the reliability of the experimental instrument, the diffusivities of sucrose aqueous solution at 298.15K were determined. The meas- ured result displays a satisfactory accuracy of the apparatus used. Furthermore, the diffusion coefficients of glynine, L-serine, L-threonine and L-valine in polyacrylamide （PAM） aqueous solution at 298.15K were measured, respec- tively. The experimental data were fitted by a newly proposed correlation equation based on Li＇s predictive model. The calculating results by the present model are at considerably good agreement with experimental values, and the maximum average deviation is only 0.5%.展开更多
An analytical model was developed to describe Si？As alloy solidification in the whole range of measured interface velocity. It is demonstrated that at low interface velocity, the solidification occurs in the initial ...An analytical model was developed to describe Si？As alloy solidification in the whole range of measured interface velocity. It is demonstrated that at low interface velocity, the solidification occurs in the initial transient regime. The model leads to good comparison with the experimental data taking both local nonequilibrium effects at high interface velocity and steady state effects at low interface velocity into account. The local nonequilibrium diffusion effects shrink the initial transient period and lead to diffusionless solidification at high interface velocity.展开更多
Due to safety concerns and habitat restoration for landlocked salmon,a 13-m high check dam on Chijiawan Creek was removed in late May 2011 in Taiwan.We conducted experiments to understand channel evolution of differen...Due to safety concerns and habitat restoration for landlocked salmon,a 13-m high check dam on Chijiawan Creek was removed in late May 2011 in Taiwan.We conducted experiments to understand channel evolution of different scenarios.We further compared our experimental results of riverbed elevation changes with the analytical solutions derived from the diffusion equation and field dynamics as well after the creek experienced the first flood event.The results indicated that magnitude of discharges and notch size are dominant factors in resulting channel evolution.While the largest differences between grain size distribution are associated with discharge,the largest differences in net change in upstream volume are associated with notch size.While the theoretical equation could help understand the channel change after dam removal,it only explained the evolution closer to the dam.The physical experiments,on the other hand,provided insights especially with regard to comparing alternative proposed management actions.The discrepancies between predicted and actual outcome highlight more needed inputs for future dam-removal assessments.展开更多
In this paper, a nonautonomous predator-prey dispersion model is studied, where all parameters are time-dependent. The system, which is consisted of n-patches, the prey specics can disperse among n-patches, but the pr...In this paper, a nonautonomous predator-prey dispersion model is studied, where all parameters are time-dependent. The system, which is consisted of n-patches, the prey specics can disperse among n-patches, but the predator species is confined to one patch and cannot disperse. It is proved the system is uniformly persistent under any dispersion rates effect. Furthermore, sufficient conditions are established for global stability of the system.展开更多
Discrete element simulations of one-dimensional compression of breakable granular assemblies were performed to investigate the capability of the exponential compression equation suggested by Bauer.The relationship bet...Discrete element simulations of one-dimensional compression of breakable granular assemblies were performed to investigate the capability of the exponential compression equation suggested by Bauer.The relationship between the so-called solid hardness and the particle strength was studied so as to provide a physical background for the introduction of a time-dependent solid hardness.A hyperbolic flow rule,describing the relationship between the inclination of the strain path and the stress ratio during wetting,was proposed based on typical triaxial wetting experiments on two different rockfill materials.The flow rule was then extended and incorporated into the transformed stress based hypoplastic model to capture the direction of creep strains.Meanwhile,a new density factor was introduced to the extended model to take into account the dependence of the magnitude of creep strains on the packing density.The stiffness tensor given by the extended model was discussed and the flowchart for the integration of the constitutive equation was designed.The extended model was then embedded into a finite element program and used to simulate the triaxial compression and wetting experiments performed on the aforementioned rockfill materials.Good agreement between the model predictions and the measured results lends sufficient credibility to the extended model in reproducing the stress-stain behaviour under loading and the creep behaviour during wetting.The extended model and the finite element program were also used to investigate the deformation behaviour of an earth-rock dam at the end of construction and during first impounding.The familiar phenomena such as the wetting induced settlement of the upstream shell and the movement of the dam crest towards the upstream were successfully captured by the numerical model,which confirms the feasibility of applying the extended model to dam engineering in the future.展开更多
In this paper, we investigate the dynamics of a diffusive predator prey model with Holling-II functional response and the additive Allee effect in prey. We show the local and global asymptotical stability of the posit...In this paper, we investigate the dynamics of a diffusive predator prey model with Holling-II functional response and the additive Allee effect in prey. We show the local and global asymptotical stability of the positive equilibrium, and give the conditions of the existence of the Hopf bifurcation. By carrying out global qualitative and bifurcation analysis, it is shown that the weak and strong Allee effects in prey can induce different dynamical behavior in the predator-prey model. Furthermore, we use some numerical simulations to illustrate the dynamics of the model. The results may be helpful for controlling and managing the predator-prey system.展开更多
In this paper, stochastic global exponential stability criteria for delayed im- pulsive Markovian jumping reaction-diffusion Cohen-Grossberg neural networks （CCNNs for short） are obtained by using a novel Lyapunov-K...In this paper, stochastic global exponential stability criteria for delayed im- pulsive Markovian jumping reaction-diffusion Cohen-Grossberg neural networks （CCNNs for short） are obtained by using a novel Lyapunov-Krasovskii functional approach, lin- ear matrix inequalities （LMIs for short） technique, Ito formula, Poincare inequality and Hardy-Poincare inequality, where the CGNNs involve uncertain parameters, partially un known Markovian transition rates, and even nonlinear p-Laplace diffusion （p 〉 1）. It is worth mentioning that ellipsoid domains in Rm （m 〉 3） can be considered in numerical simulations for the first time owing to the synthetic applications of Poincare inequality and Hardy-Poincare inequality. Moreover, the simulation numerical results show that even the corollaries of the obtained results are more feasible and effective than the main results of some recent related literatures in view of significant improvement in the Mlowable upper bounds of delays.展开更多
In this paper, a diffusive hepatitis B virus （HBV） infection model with a discrete time delay is presented and analyzed, where the spatial mobility of both intracellular capsid covered HBV DNA and HBV and the intrac...In this paper, a diffusive hepatitis B virus （HBV） infection model with a discrete time delay is presented and analyzed, where the spatial mobility of both intracellular capsid covered HBV DNA and HBV and the intracellular delay in the reproduction of infected hepatocytes are taken into account. We define the basic reproduction number R0 that determines the dynamical behavior of the model. The local and global stability of the spatially homogeneous steady states are analyzed by using the linearization technique and the direct Lyapunov method, respectively. It is shown that the susceptible uninfected steady state is globally asymptotically stable whenever R0 ≤i and is unstable whenever R0 〉1. Also, the infected steady state is globally asymptotically stable when R0 〉 1. Finally, numerical simulations are carried out to illustrate the results obtained.展开更多
文摘Mining safety and health improvements over the past decades are remarkable by many metrics, and yet the expectation of society, and the goal of the mining industry, is zero harm. If we examine the underlying enablers for the significant gains that have been achieved, the key role that research to help understand the causes of problems and to develop lasting solutions is clear. Many of the remaining challenges have been resistant to solutions by various approaches. Some, such as fatalities and injuries from ground control or powered haulage are prominent year after year. Different approaches are indicated and new solutions will be required if we are to achieve a goal of zero harm. These will originate with research, but into which topics, and what are some of these different approaches? This paper examines the current state of mine safety in the United States and highlights areas of significant opportunity for research that will lead to solutions. The likely direction of research that will enable realization of the ‘‘zero harm'' goal is described in terms of evolutionary and revolutionary approaches. Both are important, but the author's view is that some of the largest gains will be made with trans-disciplinary approaches that break from the past. Topical areas of research are suggested and several research questions are given to illustrate the direction of future research in mining safety and health.
基金the National Natural Science Foundation of China （No.20476073）.
文摘The amino acids are necessarily nutritious components, their diffusions in body fluid and blood that belong to typical non-Newtonian fluid are of virtual importance to control the diffusive process and help clinical treatment. In this article, a holographic interferometer has been adopted to measure the diffusivity of amino acids in non-Newtonian fluid with the use of real-time holographic interference technique. In order to prove the reliability of the experimental instrument, the diffusivities of sucrose aqueous solution at 298.15K were determined. The meas- ured result displays a satisfactory accuracy of the apparatus used. Furthermore, the diffusion coefficients of glynine, L-serine, L-threonine and L-valine in polyacrylamide （PAM） aqueous solution at 298.15K were measured, respec- tively. The experimental data were fitted by a newly proposed correlation equation based on Li＇s predictive model. The calculating results by the present model are at considerably good agreement with experimental values, and the maximum average deviation is only 0.5%.
基金partially supported by RFBR, research project No. 14-48-03535
文摘An analytical model was developed to describe Si？As alloy solidification in the whole range of measured interface velocity. It is demonstrated that at low interface velocity, the solidification occurs in the initial transient regime. The model leads to good comparison with the experimental data taking both local nonequilibrium effects at high interface velocity and steady state effects at low interface velocity into account. The local nonequilibrium diffusion effects shrink the initial transient period and lead to diffusionless solidification at high interface velocity.
文摘Due to safety concerns and habitat restoration for landlocked salmon,a 13-m high check dam on Chijiawan Creek was removed in late May 2011 in Taiwan.We conducted experiments to understand channel evolution of different scenarios.We further compared our experimental results of riverbed elevation changes with the analytical solutions derived from the diffusion equation and field dynamics as well after the creek experienced the first flood event.The results indicated that magnitude of discharges and notch size are dominant factors in resulting channel evolution.While the largest differences between grain size distribution are associated with discharge,the largest differences in net change in upstream volume are associated with notch size.While the theoretical equation could help understand the channel change after dam removal,it only explained the evolution closer to the dam.The physical experiments,on the other hand,provided insights especially with regard to comparing alternative proposed management actions.The discrepancies between predicted and actual outcome highlight more needed inputs for future dam-removal assessments.
基金Supported by the Natural Science Foundatioll of Henan province (994051600)
文摘In this paper, a nonautonomous predator-prey dispersion model is studied, where all parameters are time-dependent. The system, which is consisted of n-patches, the prey specics can disperse among n-patches, but the predator species is confined to one patch and cannot disperse. It is proved the system is uniformly persistent under any dispersion rates effect. Furthermore, sufficient conditions are established for global stability of the system.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51179059,90815024)the Fund for Young Scientists in Nanjing Hydraulic Research Institute (Grant No. Y312004)
文摘Discrete element simulations of one-dimensional compression of breakable granular assemblies were performed to investigate the capability of the exponential compression equation suggested by Bauer.The relationship between the so-called solid hardness and the particle strength was studied so as to provide a physical background for the introduction of a time-dependent solid hardness.A hyperbolic flow rule,describing the relationship between the inclination of the strain path and the stress ratio during wetting,was proposed based on typical triaxial wetting experiments on two different rockfill materials.The flow rule was then extended and incorporated into the transformed stress based hypoplastic model to capture the direction of creep strains.Meanwhile,a new density factor was introduced to the extended model to take into account the dependence of the magnitude of creep strains on the packing density.The stiffness tensor given by the extended model was discussed and the flowchart for the integration of the constitutive equation was designed.The extended model was then embedded into a finite element program and used to simulate the triaxial compression and wetting experiments performed on the aforementioned rockfill materials.Good agreement between the model predictions and the measured results lends sufficient credibility to the extended model in reproducing the stress-stain behaviour under loading and the creep behaviour during wetting.The extended model and the finite element program were also used to investigate the deformation behaviour of an earth-rock dam at the end of construction and during first impounding.The familiar phenomena such as the wetting induced settlement of the upstream shell and the movement of the dam crest towards the upstream were successfully captured by the numerical model,which confirms the feasibility of applying the extended model to dam engineering in the future.
文摘In this paper, we investigate the dynamics of a diffusive predator prey model with Holling-II functional response and the additive Allee effect in prey. We show the local and global asymptotical stability of the positive equilibrium, and give the conditions of the existence of the Hopf bifurcation. By carrying out global qualitative and bifurcation analysis, it is shown that the weak and strong Allee effects in prey can induce different dynamical behavior in the predator-prey model. Furthermore, we use some numerical simulations to illustrate the dynamics of the model. The results may be helpful for controlling and managing the predator-prey system.
基金supported by the National Basic Research Program of China(No.2010CB732501)the Scientific Research Fund of Science Technology Department of Sichuan Province(Nos.2010JY0057,2012JYZ010)+1 种基金the Sichuan Educational Committee Science Foundation(Nos.08ZB002,12ZB349)the Scientific Research Fund of Sichuan Provincial Education Department(Nos.14ZA0274,08ZB002,12ZB349)
文摘In this paper, stochastic global exponential stability criteria for delayed im- pulsive Markovian jumping reaction-diffusion Cohen-Grossberg neural networks （CCNNs for short） are obtained by using a novel Lyapunov-Krasovskii functional approach, lin- ear matrix inequalities （LMIs for short） technique, Ito formula, Poincare inequality and Hardy-Poincare inequality, where the CGNNs involve uncertain parameters, partially un known Markovian transition rates, and even nonlinear p-Laplace diffusion （p 〉 1）. It is worth mentioning that ellipsoid domains in Rm （m 〉 3） can be considered in numerical simulations for the first time owing to the synthetic applications of Poincare inequality and Hardy-Poincare inequality. Moreover, the simulation numerical results show that even the corollaries of the obtained results are more feasible and effective than the main results of some recent related literatures in view of significant improvement in the Mlowable upper bounds of delays.
文摘In this paper, a diffusive hepatitis B virus （HBV） infection model with a discrete time delay is presented and analyzed, where the spatial mobility of both intracellular capsid covered HBV DNA and HBV and the intracellular delay in the reproduction of infected hepatocytes are taken into account. We define the basic reproduction number R0 that determines the dynamical behavior of the model. The local and global stability of the spatially homogeneous steady states are analyzed by using the linearization technique and the direct Lyapunov method, respectively. It is shown that the susceptible uninfected steady state is globally asymptotically stable whenever R0 ≤i and is unstable whenever R0 〉1. Also, the infected steady state is globally asymptotically stable when R0 〉 1. Finally, numerical simulations are carried out to illustrate the results obtained.
