The surface of grinding 10Ni3MnCuAl steel is processed by the shot peening with different intensities. After shot peening, the metallographic structure of 10Ni3MnCuAl steel and the micro-structure on the surface layer...The surface of grinding 10Ni3MnCuAl steel is processed by the shot peening with different intensities. After shot peening, the metallographic structure of 10Ni3MnCuAl steel and the micro-structure on the surface layer are analyzed. The micro-hardness in the shot peening affected layer and the residual pressure stress are surveyed. The changes of surface quality, such as micro-hardness, metallographic structure and residual stress caused by shot peening are investigated. The result shows that shot peening can significantly improve surface quality and fatigue life of 10Ni3MnCuAl steel. The over peening effect is produced when the shot peening intensity is high, and it leads to the decrease of the fatigue life. When the optimal arc high value of shot peening is 0. 40 mm in experiments, the best surface quality is obtained and the depth of the residual stress in the precipitation-hardening layer reaches 450μm.展开更多
The equations of the lateral deflection curve of the short pier shear wall under a lateral concentrated load at any level are derived by employing a continuous approach. Lateral flexibility matrixes for the dynamic an...The equations of the lateral deflection curve of the short pier shear wall under a lateral concentrated load at any level are derived by employing a continuous approach. Lateral flexibility matrixes for the dynamic analysis are also obtained by repeatedly calculating the lateral unit load on the wall at each level where a lumped mass located. Dynamic analyses are implemented for short pier shear walls with different parameters, called the integrative coefficient and the pier strength coefficient related to the dimensions of walls. The influences of two coefficients on the dynamic performances of the structure are studied. Results indicate that with the increase of the integrative coefficient, the periods of top two modes apparently decrease but the other periods of higher frequency modes show little variation when the pier strength coefficient remains constant. Similarly, if the integrative coefficient is constant, the top two periods of the free vibration decrease with the increase of the integrative coefficient but the other periods of higher frequency modes show less variation.展开更多
The Lie symmetries of nonholonomic mechanical systems are corsidered. Some defmi tions and criteria on the Lie symmetries, and the conservation laws of the systems are given.And some examples to illustrate the applic...The Lie symmetries of nonholonomic mechanical systems are corsidered. Some defmi tions and criteria on the Lie symmetries, and the conservation laws of the systems are given.And some examples to illustrate the application of the results are provided.展开更多
Aim To study an algebraic of the dynamical equations of holonomic mechanical systems in relative motion. Methods The equations of motion were presented in a contravariant algebraic form and an algebraic product was...Aim To study an algebraic of the dynamical equations of holonomic mechanical systems in relative motion. Methods The equations of motion were presented in a contravariant algebraic form and an algebraic product was determined. Results and Conclusion The equations a Lie algebraic structure if any nonpotential generalized force doesn't exist while while the equations possess a Lie-admissible algebraic structure if nonpotential generalized forces exist .展开更多
Puts forward an algebraic structure of the Chaplygin's equations of nonholonomic systems, establish the Poisson's theory of the integration equations and gives an example for illustrating the application of th...Puts forward an algebraic structure of the Chaplygin's equations of nonholonomic systems, establish the Poisson's theory of the integration equations and gives an example for illustrating the application of the result.展开更多
Since the increasing demand for arable land and low efficient and disordered use of rural residential land,land consolidation for rural settlement has become a hot issue in China.Many Chinese scientists studied the to...Since the increasing demand for arable land and low efficient and disordered use of rural residential land,land consolidation for rural settlement has become a hot issue in China.Many Chinese scientists studied the topic from different angles.However,there is no reference systematically summarizing and discussing feasibility of consolidating rural residential land into arable land.The authors listed and analyzed the calculation methods of consolidating rural residential land into arable land,and discussed the feasibility and reasonability of those methods.Moreover,this paper put forward the study orientation in this regard for providing references for relevant researches.展开更多
Aiming at the problems of power structure irrationality, lagging of power network behind power source development and high proportion of overdone and small sized units existing currently in power system in China, fina...Aiming at the problems of power structure irrationality, lagging of power network behind power source development and high proportion of overdone and small sized units existing currently in power system in China, financial and running strategies are set forth corresponding to power system restructuring.展开更多
Based on the concept of adiabatic invariant, the perturbation and adiabatic invariants of the Mei symmetry for nonholonomic mechanical systems are studied. The exact invariants of the Mei symmetry for the system witho...Based on the concept of adiabatic invariant, the perturbation and adiabatic invariants of the Mei symmetry for nonholonomic mechanical systems are studied. The exact invariants of the Mei symmetry for the system without perturbation are given. The perturbation to the Mei symmetry is discussed and the adiabatic invariants of the Mei symmetry for the perturbed system are obtained.展开更多
The kinetics of CO2 reforming of methane has been studied at 976-1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio...The kinetics of CO2 reforming of methane has been studied at 976-1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio > 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.展开更多
Based on the theory of symmetries and conserved quantities, the exact invariants and adiabatic invariants of nonholonomic dynamical system of relative motion are studied. The perturbation to symmetries for the nonholo...Based on the theory of symmetries and conserved quantities, the exact invariants and adiabatic invariants of nonholonomic dynamical system of relative motion are studied. The perturbation to symmetries for the nonholonomic dynamical system of relative motion under small excitation is discussed. The concept of high-order adiabatic invariant is presented, and the form of exact invariants and adiabatic invariants as well as the conditions for their existence are given. Then the corresponding inverse problem is studied.展开更多
The integrating factors and conservation theorems of nonholonomic dynamical system of relative motion are studied. First, the dynamical equations of relative motion of system are written. Next, the definition of integ...The integrating factors and conservation theorems of nonholonomic dynamical system of relative motion are studied. First, the dynamical equations of relative motion of system are written. Next, the definition of integrating factors is given, and the necessary conditions for the existence of the conserved quantities are studied in detail. Then, the conservation theorem and its inverse of system are established. Finally, an example is given to illustrate the application of the result.展开更多
Based on the concept of adiabatic invariant, the perturbation to Noether Mei symmetry and adiabatic invariants for nonholonomie mechanical systems in phase space are studied. The definition of the perturbation to Noet...Based on the concept of adiabatic invariant, the perturbation to Noether Mei symmetry and adiabatic invariants for nonholonomie mechanical systems in phase space are studied. The definition of the perturbation to Noether-Mei symmetry for the system is presented, and the criterion of the perturbation to Noether-Mei symmetry is given. Meanwhile, the Noether adiabatic invariants and the Mei adiabatic invariants for the perturbed system are obtained.展开更多
The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas ...The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas with steam. The results of experiments show that the optimal conditions for methane conversion are that the molar ratio of H2O to CH4 varies from 1.1 to 1.3 and the conversion temperature varies from 1 223 to 1 273 K. The methane conversion rate is more than 95% when the molar ratio of H2O to CH4 is 1.2, the conversion temperature is above 1 223 K and the conversion time is longer than 0.75 s. Kinetic model of methane conversion was proposed. All results demonstrate that the calculated values by the kinetic model accord with the experimental data well, and the error is less than 1.5%.展开更多
A simple SI epidemic model with age of vaccination is discussed in this paper.Both vexing birth rate, the mortality rate caused by disease and vaccine waning rate areconsidered in this model. We prove that the global ...A simple SI epidemic model with age of vaccination is discussed in this paper.Both vexing birth rate, the mortality rate caused by disease and vaccine waning rate areconsidered in this model. We prove that the global dynamics is completely determined bythe basic reproductive number R(ψ)(ψ denotes per capita vaccination rate). If R(0) 〈 1,the disease-free equilibrium is a global attractor; If R(ψ) 〈: 1, the disease-free equilibriumis locally asymptotically stable; If R(ψ) :〉 1, an unique endemic equilibrium exists and islocally asymptotically stable under certain condition.展开更多
The intensive observation data of the Nansha Islands are used to study and discuss the meso-and fine-scale systems existing with large-scale monsoon circulation during the onset of the southwesterly monsoon in the low...The intensive observation data of the Nansha Islands are used to study and discuss the meso-and fine-scale systems existing with large-scale monsoon circulation during the onset of the southwesterly monsoon in the low-latitude areas of the South China Sea. Effects of low-latitude tropical meso-scale gravity waves on weather have been disclosed. The generation and transportation of the local meso-scale gravity wave have been preliminarily studied from the viewpoint of dynamics.展开更多
Chinese iris (Iris lactea Pall. var. chinensis (Fisch) Koidz.), a robust iridaceous plant, is widespread in arid and semiarid regions with high salinity. However, the mechanism of its salt tolerance is not well un...Chinese iris (Iris lactea Pall. var. chinensis (Fisch) Koidz.), a robust iridaceous plant, is widespread in arid and semiarid regions with high salinity. However, the mechanism of its salt tolerance is not well understood. In this study, plant growth, water status, content and distribution of inorganic ions, cell membrane permeability, and proline content of I. laetea under salt stress were investigated using nutrient solutions with six NaCl concentrations ranging from 0 to 350 mmol L^-1. The results indicated that the biomass, height, fresh weight, K^+ content, and K^+/Na^+ and Ca^2+/Na^+ ratios decreased with increasing NaCl stress, whereas plant water deficit and contents of Na^+ and Cl- increased with increasing NaCl stress. In all salt treatments, water deficit of shoots was found to be higher than that of roots and had a positive correlation with salt concentration. When the NaCl concentration was less than 280 mmol L^-1, the ion absorption selectivity ratio and the transportation selectivity ratio sharply increased with increasing NaCl stress. Under medium salt stress, I. lactea exhibited a strong K^+ selective absorption and the transportation of K^+ from roots to shoots increased, whereas Na^+ was not transported and was mostly retained in roots. The plants were able to maintain osmotic adjustment through the accumulation of Na^+, Cl-, and proline. On the basis of its biomass production under salt stress, I. lactea could be considered as a facultative halophyte.展开更多
Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and...Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.展开更多
For a nonholonomic mechanical system, the generalized Mei conserved quantity and the new generalized Hojman conserved quantity deduced from Noether symmetry of the system are studied. The criterion equation of the Noe...For a nonholonomic mechanical system, the generalized Mei conserved quantity and the new generalized Hojman conserved quantity deduced from Noether symmetry of the system are studied. The criterion equation of the Noether symmetry for the system is got. The conditions under which the Noether symmetry can lead to the two new conserved quantities are presented and the forms of the conserved quantities are obtained. Finally, an example is given to illustrate the application of the results.展开更多
This paper first discusses the operating principle of instantaneous reactive power theory. Then, the theory is introduced into shunt active power filter and its control scheme is studied. Finally, Matlab/Simulink powe...This paper first discusses the operating principle of instantaneous reactive power theory. Then, the theory is introduced into shunt active power filter and its control scheme is studied. Finally, Matlab/Simulink power system toolbox is used to simulate the system. In the simulation model, as the most common harmonic source, 3-phase thyristor bridge rectifier circuit is constructed. The simulation results before and after the shunt active filter was switched to the system corresponding to different firing angles of the thyristors are presented and analyzed, which demonstrate the practicability and reliability of the proposed shunt active filter scheme.展开更多
基金Supported by the National Natural Science Foundation of China(50675104)~~
文摘The surface of grinding 10Ni3MnCuAl steel is processed by the shot peening with different intensities. After shot peening, the metallographic structure of 10Ni3MnCuAl steel and the micro-structure on the surface layer are analyzed. The micro-hardness in the shot peening affected layer and the residual pressure stress are surveyed. The changes of surface quality, such as micro-hardness, metallographic structure and residual stress caused by shot peening are investigated. The result shows that shot peening can significantly improve surface quality and fatigue life of 10Ni3MnCuAl steel. The over peening effect is produced when the shot peening intensity is high, and it leads to the decrease of the fatigue life. When the optimal arc high value of shot peening is 0. 40 mm in experiments, the best surface quality is obtained and the depth of the residual stress in the precipitation-hardening layer reaches 450μm.
文摘The equations of the lateral deflection curve of the short pier shear wall under a lateral concentrated load at any level are derived by employing a continuous approach. Lateral flexibility matrixes for the dynamic analysis are also obtained by repeatedly calculating the lateral unit load on the wall at each level where a lumped mass located. Dynamic analyses are implemented for short pier shear walls with different parameters, called the integrative coefficient and the pier strength coefficient related to the dimensions of walls. The influences of two coefficients on the dynamic performances of the structure are studied. Results indicate that with the increase of the integrative coefficient, the periods of top two modes apparently decrease but the other periods of higher frequency modes show little variation when the pier strength coefficient remains constant. Similarly, if the integrative coefficient is constant, the top two periods of the free vibration decrease with the increase of the integrative coefficient but the other periods of higher frequency modes show less variation.
文摘The Lie symmetries of nonholonomic mechanical systems are corsidered. Some defmi tions and criteria on the Lie symmetries, and the conservation laws of the systems are given.And some examples to illustrate the application of the results are provided.
文摘Aim To study an algebraic of the dynamical equations of holonomic mechanical systems in relative motion. Methods The equations of motion were presented in a contravariant algebraic form and an algebraic product was determined. Results and Conclusion The equations a Lie algebraic structure if any nonpotential generalized force doesn't exist while while the equations possess a Lie-admissible algebraic structure if nonpotential generalized forces exist .
文摘Puts forward an algebraic structure of the Chaplygin's equations of nonholonomic systems, establish the Poisson's theory of the integration equations and gives an example for illustrating the application of the result.
基金Supported by the Foundation of Key Laboratory of Resources Remote Sensing and Digital Agriculture of Chinese Ministry of Agriculture (RDA0910)the Commonweal Foundation of China's National Academy(200990124)+1 种基金Major Program of National Natural Science Foundation of China(40930101)National Key Technologies R & D Program of China(2006BAC08B0404)~~
文摘Since the increasing demand for arable land and low efficient and disordered use of rural residential land,land consolidation for rural settlement has become a hot issue in China.Many Chinese scientists studied the topic from different angles.However,there is no reference systematically summarizing and discussing feasibility of consolidating rural residential land into arable land.The authors listed and analyzed the calculation methods of consolidating rural residential land into arable land,and discussed the feasibility and reasonability of those methods.Moreover,this paper put forward the study orientation in this regard for providing references for relevant researches.
文摘Aiming at the problems of power structure irrationality, lagging of power network behind power source development and high proportion of overdone and small sized units existing currently in power system in China, financial and running strategies are set forth corresponding to power system restructuring.
文摘Based on the concept of adiabatic invariant, the perturbation and adiabatic invariants of the Mei symmetry for nonholonomic mechanical systems are studied. The exact invariants of the Mei symmetry for the system without perturbation are given. The perturbation to the Mei symmetry is discussed and the adiabatic invariants of the Mei symmetry for the perturbed system are obtained.
基金the Consejo Nacional de Investigacions Cientificas y Tecnicas (CONICET).
文摘The kinetics of CO2 reforming of methane has been studied at 976-1033K on a commercial NiO/CaO/Al2O3 catalyst in a packed-bed continuous reactor. The reaction was carried out at atmospheric pressure and CO2/CH4 ratio > 2. The Hougen-Watson rate models were fitted to experimental data assuming the disso ciative adsorption of methane as the rate-determining step. The reaction rate showed an effective reaction order of about unity for CH4. The apparent activity energy was found to be 104 kJ·mol-1. Therefore the kinetic reaction parameters were determined and a possible reaction mechanism was proposed.
文摘Based on the theory of symmetries and conserved quantities, the exact invariants and adiabatic invariants of nonholonomic dynamical system of relative motion are studied. The perturbation to symmetries for the nonholonomic dynamical system of relative motion under small excitation is discussed. The concept of high-order adiabatic invariant is presented, and the form of exact invariants and adiabatic invariants as well as the conditions for their existence are given. Then the corresponding inverse problem is studied.
基金The project supported by Natural Science Foundation of Heilongjiang Province of China under Grant No. 9507
文摘The integrating factors and conservation theorems of nonholonomic dynamical system of relative motion are studied. First, the dynamical equations of relative motion of system are written. Next, the definition of integrating factors is given, and the necessary conditions for the existence of the conserved quantities are studied in detail. Then, the conservation theorem and its inverse of system are established. Finally, an example is given to illustrate the application of the result.
文摘Based on the concept of adiabatic invariant, the perturbation to Noether Mei symmetry and adiabatic invariants for nonholonomie mechanical systems in phase space are studied. The definition of the perturbation to Noether-Mei symmetry for the system is presented, and the criterion of the perturbation to Noether-Mei symmetry is given. Meanwhile, the Noether adiabatic invariants and the Mei adiabatic invariants for the perturbed system are obtained.
基金Project(291054) supported by Postdoctoral Fund of China
文摘The effects of factors such as the molar ratio of H2O to CH4 (n(H2O)/n(CH4)), methane conversion temperature and time on methane conversion rate were investigated to build kinetic model for reforming of coke-oven gas with steam. The results of experiments show that the optimal conditions for methane conversion are that the molar ratio of H2O to CH4 varies from 1.1 to 1.3 and the conversion temperature varies from 1 223 to 1 273 K. The methane conversion rate is more than 95% when the molar ratio of H2O to CH4 is 1.2, the conversion temperature is above 1 223 K and the conversion time is longer than 0.75 s. Kinetic model of methane conversion was proposed. All results demonstrate that the calculated values by the kinetic model accord with the experimental data well, and the error is less than 1.5%.
基金Supported by the NSF of China(10371105) Supported by the Youth Science Foundation of Xinyang Normal University(20060202)
文摘A simple SI epidemic model with age of vaccination is discussed in this paper.Both vexing birth rate, the mortality rate caused by disease and vaccine waning rate areconsidered in this model. We prove that the global dynamics is completely determined bythe basic reproductive number R(ψ)(ψ denotes per capita vaccination rate). If R(0) 〈 1,the disease-free equilibrium is a global attractor; If R(ψ) 〈: 1, the disease-free equilibriumis locally asymptotically stable; If R(ψ) :〉 1, an unique endemic equilibrium exists and islocally asymptotically stable under certain condition.
文摘The intensive observation data of the Nansha Islands are used to study and discuss the meso-and fine-scale systems existing with large-scale monsoon circulation during the onset of the southwesterly monsoon in the low-latitude areas of the South China Sea. Effects of low-latitude tropical meso-scale gravity waves on weather have been disclosed. The generation and transportation of the local meso-scale gravity wave have been preliminarily studied from the viewpoint of dynamics.
基金the National Natural Science Foundation of China (No.30170671).
文摘Chinese iris (Iris lactea Pall. var. chinensis (Fisch) Koidz.), a robust iridaceous plant, is widespread in arid and semiarid regions with high salinity. However, the mechanism of its salt tolerance is not well understood. In this study, plant growth, water status, content and distribution of inorganic ions, cell membrane permeability, and proline content of I. laetea under salt stress were investigated using nutrient solutions with six NaCl concentrations ranging from 0 to 350 mmol L^-1. The results indicated that the biomass, height, fresh weight, K^+ content, and K^+/Na^+ and Ca^2+/Na^+ ratios decreased with increasing NaCl stress, whereas plant water deficit and contents of Na^+ and Cl- increased with increasing NaCl stress. In all salt treatments, water deficit of shoots was found to be higher than that of roots and had a positive correlation with salt concentration. When the NaCl concentration was less than 280 mmol L^-1, the ion absorption selectivity ratio and the transportation selectivity ratio sharply increased with increasing NaCl stress. Under medium salt stress, I. lactea exhibited a strong K^+ selective absorption and the transportation of K^+ from roots to shoots increased, whereas Na^+ was not transported and was mostly retained in roots. The plants were able to maintain osmotic adjustment through the accumulation of Na^+, Cl-, and proline. On the basis of its biomass production under salt stress, I. lactea could be considered as a facultative halophyte.
基金Supported by the National Natural Science Foundation of China(51474184)the Natural Science Foundation of the State Administration of Work Safety in China(2012-387,Sichuan-0021-2016AQ)
文摘Hazardous gas detection systems play an important role in preventing catastrophic gas-related accidents in process industries. Even though effective detection technology currently exists for hazardous gas releases and a majority of process installations have a large number of sensitive detectors in place, the actual operating performance of gas detection systems still does not meet the expected requirements. In this paper, a riskbased methodology is proposed to optimize the placement of hazardous gas detectors. The methodology includes three main steps, namely, the establishment of representative leak scenarios, computational fluid dynamics(CFD)-based gas dispersion modeling, and the establishment of an optimized solution. Based on the combination of gas leak probability and joint distribution probability of wind velocity and wind direction, a quantitative filtering approach is presented to select representative leak scenarios from all potential scenarios. The commercial code ANSYS-FLUENT is used to estimate the consequence of hazardous gas dispersions under various leak and environmental conditions. A stochastic mixed-integer linear programming formulation with the objective of minimizing the total leak risk across all representative leak scenarios is proposed, and the greedy dropping heuristic algorithm(GDHA) is used to solve the optimization model. Finally, a practical application of the methodology is performed to validate its effectiveness for the optimal design of a gas detector system in a high-sulfur natural gas purification plant in Chongqing, China. The results show that an appropriate number of gas detectors with optimal cost-effectiveness can be obtained, and the total leak risk across all potential scenarios can be substantially reduced. This methodology provides an effective approach to guide the optimal placement of pointtype gas detection systems involved with either single or mixed gas releases.
文摘For a nonholonomic mechanical system, the generalized Mei conserved quantity and the new generalized Hojman conserved quantity deduced from Noether symmetry of the system are studied. The criterion equation of the Noether symmetry for the system is got. The conditions under which the Noether symmetry can lead to the two new conserved quantities are presented and the forms of the conserved quantities are obtained. Finally, an example is given to illustrate the application of the results.
文摘This paper first discusses the operating principle of instantaneous reactive power theory. Then, the theory is introduced into shunt active power filter and its control scheme is studied. Finally, Matlab/Simulink power system toolbox is used to simulate the system. In the simulation model, as the most common harmonic source, 3-phase thyristor bridge rectifier circuit is constructed. The simulation results before and after the shunt active filter was switched to the system corresponding to different firing angles of the thyristors are presented and analyzed, which demonstrate the practicability and reliability of the proposed shunt active filter scheme.