The attitude control problem and the guidance problem are solved in 3-D for a buoyancy-driven airship actuated by the combined effects of an internal air bladder which modulates the airshiprs net weight and of two mov...The attitude control problem and the guidance problem are solved in 3-D for a buoyancy-driven airship actuated by the combined effects of an internal air bladder which modulates the airshiprs net weight and of two moving masses which modulate its center of mass. A simple and clear modeling is introduced to derive the 8 degree of freedom （DOF） mathematical model. Nonlinear control loops are derived through maximal feedback linearization with internal stability for both dynamics in the longitudinal plane and in the lateral plane. Based on a singular perturbation approach, the superposition of these two control actions in the longitudinal plane and in the lateral plane is shown to achieve the control of the dynamics in 3-D space. The simulations of the airship tracking specified attitude, moving direction and speed in 3-D space are presented.展开更多
In order to diminish the impacts of extemal disturbance such as parking speed fluctuation and model un- certainty existing in steering kinematics, this paper presents a parallel path tracking method for vehicle based ...In order to diminish the impacts of extemal disturbance such as parking speed fluctuation and model un- certainty existing in steering kinematics, this paper presents a parallel path tracking method for vehicle based on pre- view back propagation （BP） neural network PID controller. The forward BP neural network can adjust the parameters of PID controller in real time. The preview time is optimized by considering path curvature, change in curvature and road boundaries. A fuzzy controller considering barriers and different road conditions is built to select the starting po- sition. In addition, a kind of path planning technology satisfying the requirement of obstacle avoidance is introduced. In order to solve the problem of discontinuous curvature, cubic B spline curve is used for curve fitting. The simulation results and real vehicle tests validate the effectiveness of the proposed path planning and tracking methods.展开更多
Objective： Radiation therapy is an important component of the multidisciplinary management of esophageal carcinoma. Three-dimensional conformal radiation therapy requires the precise definition of the target volume. ...Objective： Radiation therapy is an important component of the multidisciplinary management of esophageal carcinoma. Three-dimensional conformal radiation therapy requires the precise definition of the target volume. We aimed to compare the treatment results and radiation toxicities between three-dimensional conformal radiotherapy （3D-CRT） and conventional radiotherapy （CR） for patients with cervical and thoracic esophageal carcinoma. Methods： From June 2004 to December 2006, a random study was performed on 106 patients treated with 3D-CRT or CR, 53 patients in each group. The patients in CR group received conventional radiotherapy in 2.0 Gy/f, 5 f/week and total dose was 66-70 Gy in 6.5 or 7 weeks. The patients in 3D-CRT group were treated by 3D-CRT in 2.0 Gy/f, 5 f/week and total dose was 64-70 Gy in 6 weeks. The local control rates, survival rates and radiation toxicities for the two groups were investigated. Results： The 1-year and 3-year local control rates were 83.0% and 60.4% in 3D-CRT group and 64.2% （x^2 = 4.853, P = 0.028） and 32.1% （x^2 = 9.812, P = 0.002） in CR group. The 1-year and 3-year survival rates were 73.6% and 50.9% in 3D-CRT group and 54.7% （x^2 = 4.102, P = 0.043） and 32.1% （x^2 = 3.886, P = 0.049） in CR group. Between the two groups, there was no significant difference in radiation toxicities. Conclusien： The 1-year and 3-year local control rates and survival rates of patients with esophageal carcinoma treated by 3D-CRT is superior to CR. However, longer-term results and radiation toxicity need further study which involves more patients and prolonged follow-up.展开更多
In this paper, a neural-network-based variable structure control scheme is presented for a class of nonlinear systems with a general low triangular structure. The proposed variable structure controller is proved to be...In this paper, a neural-network-based variable structure control scheme is presented for a class of nonlinear systems with a general low triangular structure. The proposed variable structure controller is proved to be Cl, thus can be applied for backstepping design, which has extended the scope of previous nonlinear systems in the form of strict-feedback and pure-feedback. With the help of neural network approximator, H-∞ performance analysis of stability is given. The effectiveness of proposed control law is verified via simulation.展开更多
Laboratory and field studies were conducted on some aspects of biology and control methods of fruit stalk borer Oryctes elegans Prell., the study was conducted in date palm orchards in south Baghdad during the years 2...Laboratory and field studies were conducted on some aspects of biology and control methods of fruit stalk borer Oryctes elegans Prell., the study was conducted in date palm orchards in south Baghdad during the years 2009 and 2010. The laboratory rearing result ofO. elegans indicated that the larval stage period was very long reached 6 months, the body weight of the mature larva was 7.61 gm, the length and body circumference were 7.58 and 5.23 cm respectively. The period of pupa stage was 19 day and 2.97 gm body weight, while the length and body circumference were 3.74 and 3.21 cm respectively .While the weight of adult stage was 1.67 gm and 3.14 cm, 2.71 cm for the length and circumference body respectively. Results of hand collection larvae in palm trees during the regular annual service, showed reduction in population density of adults to 1.4 adult/trap per week compared with 3.3 and 14.0 adult/trap per week in the orchards were larvae collected partially and without hand collection by using the light traps with solar energy （Magna Traps, Russell IPM） respectively. Also, the study proved the existence of an inverse relation between the moon light and adult activity, which affected on the adult number cough in light traps. These results indicated that the hand collection of larvae works during months January, February, March and April at synchronized with the larval stage on palm trees, and use Magna Traps as an effective method to control O. elegans through IPM programs in palm orchards.展开更多
The inter-line dynamic voltage restorer （IDVR） consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for volta...The inter-line dynamic voltage restorer （IDVR） consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder （voltage control mode）, the other inverters pump the required power into the dc bus （power control mode）. Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered （constant impedance and three phase induction motor）. Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept.展开更多
The present study elaborates three-dimensional flow of Williamson nanoliquid over a nonlinear stretchable surface. Fluid flow obeys Darcy–Forchheimer porous medium. A bidirectional nonlinear stretching surface genera...The present study elaborates three-dimensional flow of Williamson nanoliquid over a nonlinear stretchable surface. Fluid flow obeys Darcy–Forchheimer porous medium. A bidirectional nonlinear stretching surface generates the flow. Convective surface condition of heat transfer is taken into consideration. Further the zero nanoparticles mass flux condition is imposed at the boundary. Effects of thermophoresis and Brownian diffusion are considered. Assumption of boundary layer has been employed in the problem formulation. Convergent series solutions for the nonlinear governing system are established through the optimal homotopy analysis method(OHAM). Graphs have been sketched in order to analyze that how the velocity, temperature and concentration distributions are affected by distinct emerging flow parameters. Skin friction coefficients and local Nusselt number are also computed and discussed.展开更多
This paper is concerned with the existence and the analytical approximations of limit cycles in a three-dimensional nonlinear autonomous feedback control system.Based on three-dimensional Hopf bifurcation theorem,the ...This paper is concerned with the existence and the analytical approximations of limit cycles in a three-dimensional nonlinear autonomous feedback control system.Based on three-dimensional Hopf bifurcation theorem,the existence of limit cycles is first proved.Then the homotopy analysis method(HAM) is applied to obtain the analytical approximations of the limit cycle and its frequency.In deriving the higher-order approximations,the authors utilized the idea of a perturbation procedure proposed for limit cycles' approximation in van der Pol equation.By comparing with the numerical integration solutions,it is shown that the accuracy of the analytical results obtained in this paper is very high,even when the amplitude of the limit cycle is large.展开更多
基金Supported by the Scholarship Foundation of China Scholarship Council~~
文摘The attitude control problem and the guidance problem are solved in 3-D for a buoyancy-driven airship actuated by the combined effects of an internal air bladder which modulates the airshiprs net weight and of two moving masses which modulate its center of mass. A simple and clear modeling is introduced to derive the 8 degree of freedom （DOF） mathematical model. Nonlinear control loops are derived through maximal feedback linearization with internal stability for both dynamics in the longitudinal plane and in the lateral plane. Based on a singular perturbation approach, the superposition of these two control actions in the longitudinal plane and in the lateral plane is shown to achieve the control of the dynamics in 3-D space. The simulations of the airship tracking specified attitude, moving direction and speed in 3-D space are presented.
基金Supported by the National Natural Science Foundation of China(No.11072106,No.51005133 and No.51375009)
文摘In order to diminish the impacts of extemal disturbance such as parking speed fluctuation and model un- certainty existing in steering kinematics, this paper presents a parallel path tracking method for vehicle based on pre- view back propagation （BP） neural network PID controller. The forward BP neural network can adjust the parameters of PID controller in real time. The preview time is optimized by considering path curvature, change in curvature and road boundaries. A fuzzy controller considering barriers and different road conditions is built to select the starting po- sition. In addition, a kind of path planning technology satisfying the requirement of obstacle avoidance is introduced. In order to solve the problem of discontinuous curvature, cubic B spline curve is used for curve fitting. The simulation results and real vehicle tests validate the effectiveness of the proposed path planning and tracking methods.
文摘Objective： Radiation therapy is an important component of the multidisciplinary management of esophageal carcinoma. Three-dimensional conformal radiation therapy requires the precise definition of the target volume. We aimed to compare the treatment results and radiation toxicities between three-dimensional conformal radiotherapy （3D-CRT） and conventional radiotherapy （CR） for patients with cervical and thoracic esophageal carcinoma. Methods： From June 2004 to December 2006, a random study was performed on 106 patients treated with 3D-CRT or CR, 53 patients in each group. The patients in CR group received conventional radiotherapy in 2.0 Gy/f, 5 f/week and total dose was 66-70 Gy in 6.5 or 7 weeks. The patients in 3D-CRT group were treated by 3D-CRT in 2.0 Gy/f, 5 f/week and total dose was 64-70 Gy in 6 weeks. The local control rates, survival rates and radiation toxicities for the two groups were investigated. Results： The 1-year and 3-year local control rates were 83.0% and 60.4% in 3D-CRT group and 64.2% （x^2 = 4.853, P = 0.028） and 32.1% （x^2 = 9.812, P = 0.002） in CR group. The 1-year and 3-year survival rates were 73.6% and 50.9% in 3D-CRT group and 54.7% （x^2 = 4.102, P = 0.043） and 32.1% （x^2 = 3.886, P = 0.049） in CR group. Between the two groups, there was no significant difference in radiation toxicities. Conclusien： The 1-year and 3-year local control rates and survival rates of patients with esophageal carcinoma treated by 3D-CRT is superior to CR. However, longer-term results and radiation toxicity need further study which involves more patients and prolonged follow-up.
基金Shanghai Leading Academic Discipline Project(B504)
文摘In this paper, a neural-network-based variable structure control scheme is presented for a class of nonlinear systems with a general low triangular structure. The proposed variable structure controller is proved to be Cl, thus can be applied for backstepping design, which has extended the scope of previous nonlinear systems in the form of strict-feedback and pure-feedback. With the help of neural network approximator, H-∞ performance analysis of stability is given. The effectiveness of proposed control law is verified via simulation.
文摘Laboratory and field studies were conducted on some aspects of biology and control methods of fruit stalk borer Oryctes elegans Prell., the study was conducted in date palm orchards in south Baghdad during the years 2009 and 2010. The laboratory rearing result ofO. elegans indicated that the larval stage period was very long reached 6 months, the body weight of the mature larva was 7.61 gm, the length and body circumference were 7.58 and 5.23 cm respectively. The period of pupa stage was 19 day and 2.97 gm body weight, while the length and body circumference were 3.74 and 3.21 cm respectively .While the weight of adult stage was 1.67 gm and 3.14 cm, 2.71 cm for the length and circumference body respectively. Results of hand collection larvae in palm trees during the regular annual service, showed reduction in population density of adults to 1.4 adult/trap per week compared with 3.3 and 14.0 adult/trap per week in the orchards were larvae collected partially and without hand collection by using the light traps with solar energy （Magna Traps, Russell IPM） respectively. Also, the study proved the existence of an inverse relation between the moon light and adult activity, which affected on the adult number cough in light traps. These results indicated that the hand collection of larvae works during months January, February, March and April at synchronized with the larval stage on palm trees, and use Magna Traps as an effective method to control O. elegans through IPM programs in palm orchards.
文摘The inter-line dynamic voltage restorer （IDVR） consists of several voltage source inverters connected to different independent distribution feeders with common dc bus. When one of the inverters compensates for voltage sag that appears in its feeder （voltage control mode）, the other inverters pump the required power into the dc bus （power control mode）. Each inverter will have both voltage and power controllers; only one controller is in use during the abnormal conditions according to its feeder state. The voltage controller uses one of the dynamic voltage restoration techniques. In this paper, the in-phase technique is applied and two types of loads are considered （constant impedance and three phase induction motor）. Since the voltage restoration process may need real power injection into the distribution system, the power controller injects this power via voltage injection. This voltage injection is simulated by voltage drop across series virtual impedance. A new scheme is proposed to select the impedance value. The impedance value is selected such that the power consumed by this impedance represents the required power to be transferred without perturbing the load voltage. The performance of this system is also studied during voltage swell. A scheme for operation of multi-feeder IDVR system is proposed in this paper. Simulation results substantiate the proposed concept.
文摘The present study elaborates three-dimensional flow of Williamson nanoliquid over a nonlinear stretchable surface. Fluid flow obeys Darcy–Forchheimer porous medium. A bidirectional nonlinear stretching surface generates the flow. Convective surface condition of heat transfer is taken into consideration. Further the zero nanoparticles mass flux condition is imposed at the boundary. Effects of thermophoresis and Brownian diffusion are considered. Assumption of boundary layer has been employed in the problem formulation. Convergent series solutions for the nonlinear governing system are established through the optimal homotopy analysis method(OHAM). Graphs have been sketched in order to analyze that how the velocity, temperature and concentration distributions are affected by distinct emerging flow parameters. Skin friction coefficients and local Nusselt number are also computed and discussed.
基金supported by the National Natural Science Foundations of China under Grant Nos.11201072 and 11102041the China Postdoctoral Science Foundation under Grant No.2011M500803Education Department of Fujian Province under Grant No.JA10065
文摘This paper is concerned with the existence and the analytical approximations of limit cycles in a three-dimensional nonlinear autonomous feedback control system.Based on three-dimensional Hopf bifurcation theorem,the existence of limit cycles is first proved.Then the homotopy analysis method(HAM) is applied to obtain the analytical approximations of the limit cycle and its frequency.In deriving the higher-order approximations,the authors utilized the idea of a perturbation procedure proposed for limit cycles' approximation in van der Pol equation.By comparing with the numerical integration solutions,it is shown that the accuracy of the analytical results obtained in this paper is very high,even when the amplitude of the limit cycle is large.
