Operation of a dielectric elastomer(DE)transducer is limited by the way it fails,and any other limits imposed by the user.For example,material rupture and dielectric breakdown are two examples of transducer failure,wh...Operation of a dielectric elastomer(DE)transducer is limited by the way it fails,and any other limits imposed by the user.For example,material rupture and dielectric breakdown are two examples of transducer failure,while tension loss is a user-imposed limit.Electromechanical instability may or may not result in transducer failure,but is often considered as a boundary to denote the onset of state transition.For a DE undergoing homogeneous deformation,constructing operational limits on work-conjugate state diagrams are rather straight-forward.However,for DE subjected to non-homogeneous deformation,the process is more complex.We present a method to plot the operational boundaries of a DE subject to non-homogeneous deformation,known commonly as the Universal Muscle Actuator or the loudspeaker configuration.Our analysis show that tension loss need not be imposed as a hard operational limit,and that there is further operational space for the transducer,post tension loss.By plotting the operational limits on work-conjugate planes,we determine an optimal inner-to-outer ring ratio and the required pre-stretches that maximize energy conversion.展开更多
Topology changes （reconfigurations） in the transmission system are effective remedial actions to restore fulfilling N-I security principle. In the transmission system, Slovak Republic prepares several scenarios of p...Topology changes （reconfigurations） in the transmission system are effective remedial actions to restore fulfilling N-I security principle. In the transmission system, Slovak Republic prepares several scenarios of possible reconfigurations, especially in the substation Varin and substation Lemesany. The paper describes reasons of reconfiguration necessity, preparation process, testing process, test results and comparison with expected results from simulation calculations. The conclusion summarizes advantages and disadvantages of the reconfiguration implementation in the transmission system, recommendations for real-time operation, including coordination with neighbouring transmission system operators and affected distribution system operators.展开更多
In the present paper, we obtain estimations of convergence rate derivatives of the q-Bernstein polynomials Bn （f, qn ;x） approximating to f＇ （x） as n →∞, which is a general- ization of that relating the classic...In the present paper, we obtain estimations of convergence rate derivatives of the q-Bernstein polynomials Bn （f, qn ;x） approximating to f＇ （x） as n →∞, which is a general- ization of that relating the classical case qn = 1. On the other hand, we study the conver- gence properties of derivatives of the limit q-Bernstein operators B∞（f, q;x） as q→1-.展开更多
Limiting surface soil disturbance caused by forest harvesting machines is an important task and is influenced by the selection of efficient and reliable predictors of such disturbance. Our objective was to determine w...Limiting surface soil disturbance caused by forest harvesting machines is an important task and is influenced by the selection of efficient and reliable predictors of such disturbance. Our objective was to determine whether soil moisture content affects soil load bearing capacity and the formation of ruts. Measurements were conducted in six forest stands where various machines operated. We measured the formation of ruts along skid trails in connection with varying soil moisture content. Soil moisture content was determined through the gravimetric sampling method. Our results showed that severe（rut depth16–25 cm） to very severe disturbance（rut depth [26 cm）occurred in forest stands where the instantaneous soil moisture exceeded its plasticity limits defined through Atterberg limits. Atterberg limits of soil plasticity ranged from 26 to 32 % in individual stands. Regression and correlation analysis confirmed a moderately strong relationship（R = 0.52; p ／ 0.05） between soil moisture content and average rut depth. This confirmed that soil moisture is a suitable and effective predictor of soil disturbance.展开更多
Most power transfer studies involve contingencies and multi pattern scenarios that often can only be performed in reasonable time with the use of linear methods. In these works, the effect of reactive power flows in l...Most power transfer studies involve contingencies and multi pattern scenarios that often can only be performed in reasonable time with the use of linear methods. In these works, the effect of reactive power flows in line loading is neglected while formulating the problem for ATC （available transfer capability） calculations. This paper presents the determination of shunt reactive power compensation in the presence of FACTS （flexible AC transmission system） devices like： SSSC （static synchronous series compensator） and UPFC （unified power flow controller） for enhancement of power transfer capability of a power system incorporating the reactive power flows in ATC calculations. In doing so, redistribution of power flow takes place and therefore improves ATC of the system. Studies on a sample 5-bus power system model are carried out to illustrate the effect of shunt compensation along with line flow control.展开更多
The limited area 5-level primitive equation model,as the first operational precipitation forecast model in China,has been run at Beijing (National) Meteorological Center (BMC) for more than four years.The opera- tiona...The limited area 5-level primitive equation model,as the first operational precipitation forecast model in China,has been run at Beijing (National) Meteorological Center (BMC) for more than four years.The opera- tional results show that this model gives continuous services,and the forecast skill is satisfied for the forecast of some weather situations,such as extratropical cyclone,front and the precipitation associated with them. The forecast guides are widely used at the local weather services now.展开更多
This paper develops a real-time control method based on deep reinforcement learning aimed to determine the optimal control actions to maintain a sufficient secure operating limit.The secure operating limit refers to t...This paper develops a real-time control method based on deep reinforcement learning aimed to determine the optimal control actions to maintain a sufficient secure operating limit.The secure operating limit refers to the limit to the most stressed pre-contingency operating point of an electric power system that can withstand a set of credible contingencies without violating stability criteria.The developed deep reinforcement learning method uses a hybrid control scheme that is capable of simultaneously adjusting both discrete and continuous action variables.The performance is evaluated on a modified version of the Nordic32 test system.The results show that the developed deep reinforcement learning method quickly learns an effective control policy to ensure a sufficient secure operating limit for a range of different system scenarios.The performance is also compared to a control based on a rule-based look-up table and a deep reinforcement learning control adapted for discrete action spaces.The hybrid deep reinforcement learning control managed to achieve significantly better on all of the defined test sets,indicating that the possibility of adjusting both discrete and continuous action variables resulted in a more flexible and efficient control policy.展开更多
In order to make the power level angle(PLA)have the same bijection relationship with the thrust when the environment changes before operational limit exceedance,and ensure the pilot's ability of unrestricted throt...In order to make the power level angle(PLA)have the same bijection relationship with the thrust when the environment changes before operational limit exceedance,and ensure the pilot's ability of unrestricted throttle movement as well as the safety of the engine,a method used to design a constant thrust power schedule was proposed.The research was based on a simulink turbofan engine model and the results were organized as look-up tables in different structures with limitations.Simulation was done to confirm the validity and demonstrate the effectiveness of the schedule obtained with the approach.The constant thrust takeoff schedule,constant thrust idle schedule and constant thrust part power schedule with the present constant thrust control(CTC)method were proved to be valid.The results can be applied to this specific engine but the method can be applied to any areoengine and can be even extended to the unmanned plane.展开更多
The operating mechanism of the pulsating heat pipe （PHP） is not well understood and the present technology cannot predict required design parameters for a given task. The aim of research work presented in this paper...The operating mechanism of the pulsating heat pipe （PHP） is not well understood and the present technology cannot predict required design parameters for a given task. The aim of research work presented in this paper is to better understand the operation regimes of the PHP through experimental investigations. A series of experiments were conducted on a closed loop PHP with 5 turns made of copper capillary tube of 2 mm in inner diameter. Two different working fluids viz. ethanol and acetone were employed. The operating characteristics were studied for the variation of heat input, filling ratio （FR） and inclination angle of the tested device. The results strongly demonstrate the effect of the filling ratio of the working fluid on the operational stability and heat transfer capability of the device. Important insight into the operational characteristics of PHP has been obtained.展开更多
Quantum information system is fragile to be disturbed by the external environment. Quantum switching architecture is one of the promising schemes for transferring input quantum data to its destination port substituted...Quantum information system is fragile to be disturbed by the external environment. Quantum switching architecture is one of the promising schemes for transferring input quantum data to its destination port substituted for fully connected quantum networks. Since at present, interactions between the qubits are limited to a small number of neighboring qubits, one novel approach was extended, and the improved architecture was further demonstrated under limited nonlocal operation. The performance evaluation shows that the whole architecture with improved control module can achieve a time complexity of O（n^2） and will be more feasible for physical realization.展开更多
基金This work was supported by the Agency for Science,Technology and Research(Singapore)and Department of Science&Technology(India)(A*STAR-DST)[R-265-000-524-305(SERC 1425203140)]。
文摘Operation of a dielectric elastomer(DE)transducer is limited by the way it fails,and any other limits imposed by the user.For example,material rupture and dielectric breakdown are two examples of transducer failure,while tension loss is a user-imposed limit.Electromechanical instability may or may not result in transducer failure,but is often considered as a boundary to denote the onset of state transition.For a DE undergoing homogeneous deformation,constructing operational limits on work-conjugate state diagrams are rather straight-forward.However,for DE subjected to non-homogeneous deformation,the process is more complex.We present a method to plot the operational boundaries of a DE subject to non-homogeneous deformation,known commonly as the Universal Muscle Actuator or the loudspeaker configuration.Our analysis show that tension loss need not be imposed as a hard operational limit,and that there is further operational space for the transducer,post tension loss.By plotting the operational limits on work-conjugate planes,we determine an optimal inner-to-outer ring ratio and the required pre-stretches that maximize energy conversion.
文摘Topology changes （reconfigurations） in the transmission system are effective remedial actions to restore fulfilling N-I security principle. In the transmission system, Slovak Republic prepares several scenarios of possible reconfigurations, especially in the substation Varin and substation Lemesany. The paper describes reasons of reconfiguration necessity, preparation process, testing process, test results and comparison with expected results from simulation calculations. The conclusion summarizes advantages and disadvantages of the reconfiguration implementation in the transmission system, recommendations for real-time operation, including coordination with neighbouring transmission system operators and affected distribution system operators.
文摘In the present paper, we obtain estimations of convergence rate derivatives of the q-Bernstein polynomials Bn （f, qn ;x） approximating to f＇ （x） as n →∞, which is a general- ization of that relating the classical case qn = 1. On the other hand, we study the conver- gence properties of derivatives of the limit q-Bernstein operators B∞（f, q;x） as q→1-.
基金financed by a scientific grant VEGA-1/0678/14‘‘Optimization of technological,technical,economic and biological principles of energy dendromass production’’
文摘Limiting surface soil disturbance caused by forest harvesting machines is an important task and is influenced by the selection of efficient and reliable predictors of such disturbance. Our objective was to determine whether soil moisture content affects soil load bearing capacity and the formation of ruts. Measurements were conducted in six forest stands where various machines operated. We measured the formation of ruts along skid trails in connection with varying soil moisture content. Soil moisture content was determined through the gravimetric sampling method. Our results showed that severe（rut depth16–25 cm） to very severe disturbance（rut depth [26 cm）occurred in forest stands where the instantaneous soil moisture exceeded its plasticity limits defined through Atterberg limits. Atterberg limits of soil plasticity ranged from 26 to 32 % in individual stands. Regression and correlation analysis confirmed a moderately strong relationship（R = 0.52; p ／ 0.05） between soil moisture content and average rut depth. This confirmed that soil moisture is a suitable and effective predictor of soil disturbance.
文摘Most power transfer studies involve contingencies and multi pattern scenarios that often can only be performed in reasonable time with the use of linear methods. In these works, the effect of reactive power flows in line loading is neglected while formulating the problem for ATC （available transfer capability） calculations. This paper presents the determination of shunt reactive power compensation in the presence of FACTS （flexible AC transmission system） devices like： SSSC （static synchronous series compensator） and UPFC （unified power flow controller） for enhancement of power transfer capability of a power system incorporating the reactive power flows in ATC calculations. In doing so, redistribution of power flow takes place and therefore improves ATC of the system. Studies on a sample 5-bus power system model are carried out to illustrate the effect of shunt compensation along with line flow control.
文摘The limited area 5-level primitive equation model,as the first operational precipitation forecast model in China,has been run at Beijing (National) Meteorological Center (BMC) for more than four years.The opera- tional results show that this model gives continuous services,and the forecast skill is satisfied for the forecast of some weather situations,such as extratropical cyclone,front and the precipitation associated with them. The forecast guides are widely used at the local weather services now.
文摘This paper develops a real-time control method based on deep reinforcement learning aimed to determine the optimal control actions to maintain a sufficient secure operating limit.The secure operating limit refers to the limit to the most stressed pre-contingency operating point of an electric power system that can withstand a set of credible contingencies without violating stability criteria.The developed deep reinforcement learning method uses a hybrid control scheme that is capable of simultaneously adjusting both discrete and continuous action variables.The performance is evaluated on a modified version of the Nordic32 test system.The results show that the developed deep reinforcement learning method quickly learns an effective control policy to ensure a sufficient secure operating limit for a range of different system scenarios.The performance is also compared to a control based on a rule-based look-up table and a deep reinforcement learning control adapted for discrete action spaces.The hybrid deep reinforcement learning control managed to achieve significantly better on all of the defined test sets,indicating that the possibility of adjusting both discrete and continuous action variables resulted in a more flexible and efficient control policy.
文摘In order to make the power level angle(PLA)have the same bijection relationship with the thrust when the environment changes before operational limit exceedance,and ensure the pilot's ability of unrestricted throttle movement as well as the safety of the engine,a method used to design a constant thrust power schedule was proposed.The research was based on a simulink turbofan engine model and the results were organized as look-up tables in different structures with limitations.Simulation was done to confirm the validity and demonstrate the effectiveness of the schedule obtained with the approach.The constant thrust takeoff schedule,constant thrust idle schedule and constant thrust part power schedule with the present constant thrust control(CTC)method were proved to be valid.The results can be applied to this specific engine but the method can be applied to any areoengine and can be even extended to the unmanned plane.
文摘The operating mechanism of the pulsating heat pipe （PHP） is not well understood and the present technology cannot predict required design parameters for a given task. The aim of research work presented in this paper is to better understand the operation regimes of the PHP through experimental investigations. A series of experiments were conducted on a closed loop PHP with 5 turns made of copper capillary tube of 2 mm in inner diameter. Two different working fluids viz. ethanol and acetone were employed. The operating characteristics were studied for the variation of heat input, filling ratio （FR） and inclination angle of the tested device. The results strongly demonstrate the effect of the filling ratio of the working fluid on the operational stability and heat transfer capability of the device. Important insight into the operational characteristics of PHP has been obtained.
基金the National Natural Science Foundation of China （60433050, 60274025）.
文摘Quantum information system is fragile to be disturbed by the external environment. Quantum switching architecture is one of the promising schemes for transferring input quantum data to its destination port substituted for fully connected quantum networks. Since at present, interactions between the qubits are limited to a small number of neighboring qubits, one novel approach was extended, and the improved architecture was further demonstrated under limited nonlocal operation. The performance evaluation shows that the whole architecture with improved control module can achieve a time complexity of O（n^2） and will be more feasible for physical realization.
