The local chaos characteristics of the time series pressure fluctuations of gas liquid two phase flow in a self aspirated reversed flow jet loop reactor are studied by the deterministic chaos analysis technique. It...The local chaos characteristics of the time series pressure fluctuations of gas liquid two phase flow in a self aspirated reversed flow jet loop reactor are studied by the deterministic chaos analysis technique. It is found that the estimated local largest Lyapunov exponent is positive in all cases and the profile is similar to that of the local fractal dimension in this reactor. The positive largest Lyapunov exponent shows that the reactor is a nonlinear chaotic system. The obvious distribution indicates that the local nonlinear characteristic parameters such as the Lyapunov exponent and the fractal dimension could be applied to further study the flow characteristics such as the flow regine transitions and flow structures of the multi phase reactors.展开更多
The asymmetric semi-circular bend(ASCB)specimen has been proposed to investigate the cracking behavior in different geo and construction materials and attracted the attention of researchers due to its advantages.Howev...The asymmetric semi-circular bend(ASCB)specimen has been proposed to investigate the cracking behavior in different geo and construction materials and attracted the attention of researchers due to its advantages.However,there are few studies on the fracture toughness determination of rock materials.In this work,a series of fracture tests were performed with the ASCB specimens made of granite.The onset of fracture,crack initiation angle and crack propagating trajectory was analyzed in detail combined with several mixed mode fracture criteria.The influence of the crack length on the mode Ⅰ/Ⅱ fracture toughness was studied.A comparison between the fracture toughness ratios predicted by varying criteria and experimental results was conducted.The relationship between experimentally determined crack initiation angles and curves of the generalized maximum tangential stress(GMTS)criterion was obtained.The fracture process of the specimen was recorded with the high-speed camera.The shortcomings of the ASCB specimens for the fracture toughness determination of rock materials were discussed.The results may provide a reference for analysis of mixed mode I and II fracture behavior of brittle materials.展开更多
To study the dynamics of mixed traffic flow consisting of motorized and non-motorized vehicles, a carfollowing model based on the principle of collision free and cautious driving is proposed. Lateral friction and over...To study the dynamics of mixed traffic flow consisting of motorized and non-motorized vehicles, a carfollowing model based on the principle of collision free and cautious driving is proposed. Lateral friction and overlapping driving are introduced to describe the interactions between motorized vehicles and non-motorized vehicles. By numerical simulations, the flux-density relation, the temporal-spatial dynamics, and the velocity evolution are investigated in detail The results indicate non-motorized vehicles have a significant impact on the motorized vehicle flow and cause the maximum flux to decline by about 13%. Non-motorized vehicles can decrease the motorized vehicle velocity and cause velocity oscillation when the motorized vehicle density is low. Moreover, non-motorized vehicles show a significant damping effect on the oscillating velocity when the density is medium and high, and such an effect weakens as motorized vehicle density increases. The results also stress the necessity for separating motorized vehicles from non-motorized vehicles.展开更多
In PV （photovoltaic） power systems, a MPPT （maximum power point tracking） algorithm is vital in increasing their efficiency. But it is also vital to take into account the non ideal conditions resulting from comple...In PV （photovoltaic） power systems, a MPPT （maximum power point tracking） algorithm is vital in increasing their efficiency. But it is also vital to take into account the non ideal conditions resulting from complex physical environments in such PV power systems. To minimize the degradation of performances caused by these conditions, and therefore adding reliability and robustness, this paper presents an implementation of a digitally controlled system using a topology based on series connected DC-DC buck converters for a stand-alone PV power system applications, operating with local and autonomous controls, to track the maximum power points of PV modules in non ideal conditions. Simulations are carried out by using C-MEX S-functions under MATLAB-SIMULINK environment. A PV system of 1.44 kWc is described and simulation results are presented.展开更多
Small cells have been regarded as an appealing technique to boost resource reuse ratio. On the other hand, their large-scale and self-organised tendency would complicate the interference environment of mobile networks...Small cells have been regarded as an appealing technique to boost resource reuse ratio. On the other hand, their large-scale and self-organised tendency would complicate the interference environment of mobile networks. Meanwhile, traffic class is booming in recent years, which leads to higher demand for net- work designers on Quality of Service （QoS） provision, and therefore users＇ diverse re- quirements may not be guaranteed in sucff＇an interference limited scenario. To maximise the number of users with QoS demands as well as resource reuse ratio, we formulate the resource allocation problem into a multi-objective l0 norm form. It is shown to be NP hard, and an iterative method is employed to approach the optimal solution. Because of its limit of being not adaptive to large-scale networks, we also design a heuristic method based on chordal graph, which, however, could result in per- formance loss when the size of networks is small. Finally, by combining these two meth- ods, we devise a hybrid algorithm such that the allocation performs both efficiently and effectively. Simulation results illustrate the performance of our proposed methods in terms of outage probability and resource reuse ratio.展开更多
The technical characteristics and operational principal of the reverse circulation DTH hammer drilling technology is integrated introduced in this paper. Using simulation technology to assist the drilling tool design,...The technical characteristics and operational principal of the reverse circulation DTH hammer drilling technology is integrated introduced in this paper. Using simulation technology to assist the drilling tool design, the optimum designed DTH hammer gets stable performance, and the bit has reverse circulation ability, and further more, it has already developed serial products. The reverse circulation DTH hammer drilling technique has been fully applied in field such as the geological core exploration in complex strata, water well drilling, and large diameter rock embedding piles drilling in hard rock, and obviously, it is achieved favorable economic and social benefits.展开更多
The negative externalities of businesses brought serious social and environmental problems. Based on externality theory and game theory, the author in-depth analyzes intrinsic motivation of corporate social responsibi...The negative externalities of businesses brought serious social and environmental problems. Based on externality theory and game theory, the author in-depth analyzes intrinsic motivation of corporate social responsibility, and points out that corporate social responsibility will increase production costs, so companies will not take the initiative to raise the level of social responsibility. Through the analysis of corporate social responsibility profits, the paper reveals that if the government lack reasonable system to regulate corporate behavior, then the In＇m, pursuiting maximizing profit, will choose the Nash equilibrium ofconsumpting public resources, and not take the initiative to fulfill their social responsibility to seek the Pareto equilibrium of the whole regional optimal, which results in high output and low returns. The research finds that the government should strengthen the publicity of corporate social responsibility, privatization of corporate social responsibility benefits and establishment of corporate social responsibility system and other means to guide and standardize the corporate social responsihility.展开更多
The economic development bring serious environmental problems to China, the quality of atmospheric environment has an important bearing on the forecast. Be aimed at the complexity and non-linear of the quality of atmo...The economic development bring serious environmental problems to China, the quality of atmospheric environment has an important bearing on the forecast. Be aimed at the complexity and non-linear of the quality of atmospheric environment, chaos theory has been put forward which takes full advantage of using date information. Based on the reconstruction of time-series phase space of the quality of atmospheric environment with the use of least squares support vector machine theory, the atmospheric environment prediction model was built up, and 25 years of historical data viewed as the raw data of the quality of the environment in Benxi City, giving a practical example, it shows that the results forecasted by the least squares support vector machine and the actual results match the better the forecast accuracy also meet the engineering application.展开更多
The electrical power generation from low temperature heat source attracts more and more attentions but the temperature mismatching between the heat sources and working medium in the organic Rankine cycle(ORC)becomes a...The electrical power generation from low temperature heat source attracts more and more attentions but the temperature mismatching between the heat sources and working medium in the organic Rankine cycle(ORC)becomes an issue.The organic flash cycle(OFC)is an effective solution to this issue.In this paper,the OFC is analyzed by the concept of entransy loss and the T-Q(temperature-heat flow rate)diagram for the heat-work conversion.The equations for cycles of the basic OFC and the OFC whose heat source is the exhaust gas of the turbine in a Brayton cycle(the combined cycle)are derived theoretically and the results indicate that larger entransy loss rate leads to larger output power with prescribed inlet parameters of the hot stream in the discussed cases,which is displayed by the T-Qdiagram intuitively.Two numerical examples demonstrate that the optimal mass flow rate of the working medium for the maximum entransy loss rate is the same as that for the maximum output power.The T-Qdiagram analyses is in accordance with the numerical results.The concept of entransy loss can be used as the criteria for the OFC optimization.展开更多
文摘The local chaos characteristics of the time series pressure fluctuations of gas liquid two phase flow in a self aspirated reversed flow jet loop reactor are studied by the deterministic chaos analysis technique. It is found that the estimated local largest Lyapunov exponent is positive in all cases and the profile is similar to that of the local fractal dimension in this reactor. The positive largest Lyapunov exponent shows that the reactor is a nonlinear chaotic system. The obvious distribution indicates that the local nonlinear characteristic parameters such as the Lyapunov exponent and the fractal dimension could be applied to further study the flow characteristics such as the flow regine transitions and flow structures of the multi phase reactors.
基金Projects(52004182,51804110,51904101)supported by the National Natural Science Foundation of ChinaProject(2020JJ5188)supported by the Natural Science Foundation of Hunan Province,China。
文摘The asymmetric semi-circular bend(ASCB)specimen has been proposed to investigate the cracking behavior in different geo and construction materials and attracted the attention of researchers due to its advantages.However,there are few studies on the fracture toughness determination of rock materials.In this work,a series of fracture tests were performed with the ASCB specimens made of granite.The onset of fracture,crack initiation angle and crack propagating trajectory was analyzed in detail combined with several mixed mode fracture criteria.The influence of the crack length on the mode Ⅰ/Ⅱ fracture toughness was studied.A comparison between the fracture toughness ratios predicted by varying criteria and experimental results was conducted.The relationship between experimentally determined crack initiation angles and curves of the generalized maximum tangential stress(GMTS)criterion was obtained.The fracture process of the specimen was recorded with the high-speed camera.The shortcomings of the ASCB specimens for the fracture toughness determination of rock materials were discussed.The results may provide a reference for analysis of mixed mode I and II fracture behavior of brittle materials.
基金Supported by the National Basic Research Program of China under Grant No.2006CB705500the National Natural Science Foundation of China under Grant Nos.70631001 and 70701004
文摘To study the dynamics of mixed traffic flow consisting of motorized and non-motorized vehicles, a carfollowing model based on the principle of collision free and cautious driving is proposed. Lateral friction and overlapping driving are introduced to describe the interactions between motorized vehicles and non-motorized vehicles. By numerical simulations, the flux-density relation, the temporal-spatial dynamics, and the velocity evolution are investigated in detail The results indicate non-motorized vehicles have a significant impact on the motorized vehicle flow and cause the maximum flux to decline by about 13%. Non-motorized vehicles can decrease the motorized vehicle velocity and cause velocity oscillation when the motorized vehicle density is low. Moreover, non-motorized vehicles show a significant damping effect on the oscillating velocity when the density is medium and high, and such an effect weakens as motorized vehicle density increases. The results also stress the necessity for separating motorized vehicles from non-motorized vehicles.
文摘In PV （photovoltaic） power systems, a MPPT （maximum power point tracking） algorithm is vital in increasing their efficiency. But it is also vital to take into account the non ideal conditions resulting from complex physical environments in such PV power systems. To minimize the degradation of performances caused by these conditions, and therefore adding reliability and robustness, this paper presents an implementation of a digitally controlled system using a topology based on series connected DC-DC buck converters for a stand-alone PV power system applications, operating with local and autonomous controls, to track the maximum power points of PV modules in non ideal conditions. Simulations are carried out by using C-MEX S-functions under MATLAB-SIMULINK environment. A PV system of 1.44 kWc is described and simulation results are presented.
基金ACKNOWLEDGEMENT First, thanks for the invitation from the organ- isers of IEEE/CIC ICCC 2013 held in Xi＇an, China. This work was supported by the Na- tional Natural Science Foundation of China under Grants No. 60972047, No. 61231008 the National Science and Technology Major Project under Grams No. 2011ZX03005-004, No. 2011ZX03004-003, No. 2011ZX03005- 003-03, No. 2013ZX03004007-003+4 种基金 the Shannxi 13115 Project under Grant No. 2010ZDKG-26 the National Basic Research Program of China （973 Program） under Grant No. 2009CB320404 the Program for Changjiang Scholars and Inn- ovative Research Team in University under Gr- ant No. IRT0852 the 111 Project under Grant No. B08038 and the State Key Laboratory Fou- ndation under Grants No. ISN1002005, No. ISN090305.
文摘Small cells have been regarded as an appealing technique to boost resource reuse ratio. On the other hand, their large-scale and self-organised tendency would complicate the interference environment of mobile networks. Meanwhile, traffic class is booming in recent years, which leads to higher demand for net- work designers on Quality of Service （QoS） provision, and therefore users＇ diverse re- quirements may not be guaranteed in sucff＇an interference limited scenario. To maximise the number of users with QoS demands as well as resource reuse ratio, we formulate the resource allocation problem into a multi-objective l0 norm form. It is shown to be NP hard, and an iterative method is employed to approach the optimal solution. Because of its limit of being not adaptive to large-scale networks, we also design a heuristic method based on chordal graph, which, however, could result in per- formance loss when the size of networks is small. Finally, by combining these two meth- ods, we devise a hybrid algorithm such that the allocation performs both efficiently and effectively. Simulation results illustrate the performance of our proposed methods in terms of outage probability and resource reuse ratio.
基金Supported by the Fundamental Research Funds for Jilin University (No. 200903203)
文摘The technical characteristics and operational principal of the reverse circulation DTH hammer drilling technology is integrated introduced in this paper. Using simulation technology to assist the drilling tool design, the optimum designed DTH hammer gets stable performance, and the bit has reverse circulation ability, and further more, it has already developed serial products. The reverse circulation DTH hammer drilling technique has been fully applied in field such as the geological core exploration in complex strata, water well drilling, and large diameter rock embedding piles drilling in hard rock, and obviously, it is achieved favorable economic and social benefits.
文摘The negative externalities of businesses brought serious social and environmental problems. Based on externality theory and game theory, the author in-depth analyzes intrinsic motivation of corporate social responsibility, and points out that corporate social responsibility will increase production costs, so companies will not take the initiative to raise the level of social responsibility. Through the analysis of corporate social responsibility profits, the paper reveals that if the government lack reasonable system to regulate corporate behavior, then the In＇m, pursuiting maximizing profit, will choose the Nash equilibrium ofconsumpting public resources, and not take the initiative to fulfill their social responsibility to seek the Pareto equilibrium of the whole regional optimal, which results in high output and low returns. The research finds that the government should strengthen the publicity of corporate social responsibility, privatization of corporate social responsibility benefits and establishment of corporate social responsibility system and other means to guide and standardize the corporate social responsihility.
文摘The economic development bring serious environmental problems to China, the quality of atmospheric environment has an important bearing on the forecast. Be aimed at the complexity and non-linear of the quality of atmospheric environment, chaos theory has been put forward which takes full advantage of using date information. Based on the reconstruction of time-series phase space of the quality of atmospheric environment with the use of least squares support vector machine theory, the atmospheric environment prediction model was built up, and 25 years of historical data viewed as the raw data of the quality of the environment in Benxi City, giving a practical example, it shows that the results forecasted by the least squares support vector machine and the actual results match the better the forecast accuracy also meet the engineering application.
基金The National Natural Science Foundation of China(Grant No.51376101)Science Fund for Creative Research Groups(Grant No.51321002)Tsinghua University Initiative Scientific Research Program
文摘The electrical power generation from low temperature heat source attracts more and more attentions but the temperature mismatching between the heat sources and working medium in the organic Rankine cycle(ORC)becomes an issue.The organic flash cycle(OFC)is an effective solution to this issue.In this paper,the OFC is analyzed by the concept of entransy loss and the T-Q(temperature-heat flow rate)diagram for the heat-work conversion.The equations for cycles of the basic OFC and the OFC whose heat source is the exhaust gas of the turbine in a Brayton cycle(the combined cycle)are derived theoretically and the results indicate that larger entransy loss rate leads to larger output power with prescribed inlet parameters of the hot stream in the discussed cases,which is displayed by the T-Qdiagram intuitively.Two numerical examples demonstrate that the optimal mass flow rate of the working medium for the maximum entransy loss rate is the same as that for the maximum output power.The T-Qdiagram analyses is in accordance with the numerical results.The concept of entransy loss can be used as the criteria for the OFC optimization.
